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1
Poulos, Helen, Andrew Barton, Jasper Slingsby, and David Bowman. "Do Mixed Fire Regimes Shape Plant Flammability and Post-Fire Recovery Strategies?" Fire 1, no. 3 (October 22, 2018): 39. http://dx.doi.org/10.3390/fire1030039.
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The development of frameworks for better-understanding ecological syndromes and putative evolutionary strategies of plant adaptation to fire has recently received a flurry of attention, including a new model hypothesizing that plants have diverged into three different plant flammability strategies due to natural selection. We provide three case studies of pyromes/taxa (Pinus, the Proteaceae of the Cape Floristic Region, and Eucalyptus) that, contrary to model assumptions, reveal that plant species often exhibit traits of more than one of these flammability and post-fire recovery strategies. We propose that such multiple-strategy adaptations have been favoured as bet-hedging strategies in response to selective pressure from mixed-fire regimes experienced by these species over evolutionary time.
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Rosell, Julieta A. "Bark in Woody Plants: Understanding the Diversity of a Multifunctional Structure." Integrative and Comparative Biology 59, no. 3 (May 23, 2019): 535–47. http://dx.doi.org/10.1093/icb/icz057.
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Abstract Most biological structures carry out multiple functions. Focusing on only one function to make adaptive inferences overlooks that manifold selection pressures and tradeoffs shape the characteristics of a multifunctional structure. Focusing on single functions can only lead to a partial picture of the causes underlying diversity and the evolutionary origin of the structure in question. I illustrate this discussion using bark as a study case. Bark comprises all the tissues surrounding the xylem in woody plants. Broadly, bark includes an inner and mostly living region and an outer, dead one. Of all plant structures, bark has the most complex anatomical structure and ontogenetic origin involving two (and often three) different meristems. Traditionally, the wide diversity in bark traits, mainly bark thickness, has been interpreted as the result of the selective pressures imposed by fire regime. However, recent research has shown that explanations based on fire regime cannot account for salient patterns of bark variation globally including the very strong inner bark thickness–stem diameter scaling, which is likely due to metabolic needs, and the very high intracommunity variation in total, inner, and outer bark thickness, and in inner:outer proportions. Moreover, explanations based on fire disregard that in addition to fire protection, bark carries out several other crucial functions for plants including translocation of photosynthates; storage of starch, soluble sugars, water, and other compounds; protection from herbivores, pathogens, and high temperatures; wound closure, as well as mechanical support, photosynthesis, and likely being involved in xylem embolism repair. All these functions are crucial for plant performance and are involved in synergistic (e.g., storage of water and insulation) and trade-off relationships (e.g., protection from fire vs photosynthetic activity). Focusing on only one of these functions, protection from fire has provided an incomplete picture of the selective forces shaping bark diversity and has severely hindered our incipient understanding of the functional ecology of this crucial region of woody stems. Applying a multifunctional perspective to the study of bark will allow us to address why we observe such high intracommunity variation in bark traits, why some bark trait combinations are ontogenetically impossible or penalized by selection, how bark is coordinated functionally with other plant parts, and as a result, to understand how bark contributes to the vast diversity of plant ecological strategies across the globe.
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Healy, Kevin, Thomas Guillerme, Sive Finlay, Adam Kane, Seán B. A. Kelly, Deirdre McClean, David J. Kelly, Ian Donohue, Andrew L. Jackson, and Natalie Cooper. "Ecology and mode-of-life explain lifespan variation in birds and mammals." Proceedings of the Royal Society B: Biological Sciences 281, no. 1784 (June 7, 2014): 20140298. http://dx.doi.org/10.1098/rspb.2014.0298.
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Maximum lifespan in birds and mammals varies strongly with body mass such that large species tend to live longer than smaller species. However, many species live far longer than expected given their body mass. This may reflect interspecific variation in extrinsic mortality, as life-history theory predicts investment in long-term survival is under positive selection when extrinsic mortality is reduced. Here, we investigate how multiple ecological and mode-of-life traits that should reduce extrinsic mortality (including volancy (flight capability), activity period, foraging environment and fossoriality), simultaneously influence lifespan across endotherms. Using novel phylogenetic comparative analyses and to our knowledge, the most species analysed to date ( n = 1368), we show that, over and above the effect of body mass, the most important factor enabling longer lifespan is the ability to fly. Within volant species, lifespan depended upon when (day, night, dusk or dawn), but not where (in the air, in trees or on the ground), species are active. However, the opposite was true for non-volant species, where lifespan correlated positively with both arboreality and fossoriality. Our results highlight that when studying the molecular basis behind cellular processes such as those underlying lifespan, it is important to consider the ecological selection pressures that shaped them over evolutionary time.
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Camarillo, Henry, and Martha M. Muñoz. "Weak Relationships Between Swimming Morphology and Water Depth in Wrasses and Parrotfish Belie Multiple Selective Demands on Form–Function Evolution." Integrative and Comparative Biology 60, no. 5 (May 25, 2020): 1309–19. http://dx.doi.org/10.1093/icb/icaa041.
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Synopsis Mechanical tradeoffs in performance are predicted to sculpt macroevolutionary patterns of morphological diversity across environmental gradients. Water depth shapes the amount of wave energy organisms’ experience, which should result in evolutionary tradeoffs between speed and maneuverability in fish swimming morphology. Here, we tested whether morphological evolution would reflect functional tradeoffs in swimming performance in 131 species of wrasses and parrotfish (Family: Labridae) across a water depth gradient. We found that maximum water depth predicts variation in pectoral fin aspect ratio (AR) in wrasses, but not in parrotfish. Shallow-water wrasses exhibit wing-like pectoral fins that help with “flapping,” which allows more efficient swimming at faster speeds. Deeper water species, in contrast, exhibit more paddle-like pectoral fins associated with enhanced maneuverability at slower speeds. Functional morphology responds to a number of different, potentially contrasting selective pressures. Furthermore, many-to-one mapping may release some traits from selection on performance at the expense of others. As such, deciphering the signatures of mechanical tradeoffs on phenotypic evolution will require integrating multiple aspects of ecological and morphological variation. As the field of evolutionary biomechanics moves into the era of big data, we will be uniquely poised to disentangle the intrinsic and extrinsic predictors of functional diversity.
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Burkepile, Deron E., and John D. Parker. "Recent advances in plant-herbivore interactions." F1000Research 6 (February 8, 2017): 119. http://dx.doi.org/10.12688/f1000research.10313.1.
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Plant-herbivore interactions shape community dynamics across marine, freshwater, and terrestrial habitats. From amphipods to elephants and from algae to trees, plant-herbivore relationships are the crucial link generating animal biomass (and human societies) from mere sunlight. These interactions are, thus, pivotal to understanding the ecology and evolution of virtually any ecosystem. Here, we briefly highlight recent advances in four areas of plant-herbivore interactions: (1) plant defense theory, (2) herbivore diversity and ecosystem function, (3) predation risk aversion and herbivory, and (4) how a changing climate impacts plant-herbivore interactions. Recent advances in plant defense theory, for example, highlight how plant life history and defense traits affect and are affected by multiple drivers, including enemy pressure, resource availability, and the local plant neighborhood, resulting in trait-mediated feedback loops linking trophic interactions with ecosystem nutrient dynamics. Similarly, although the positive effect of consumer diversity on ecosystem function has long been recognized, recent advances using DNA barcoding to elucidate diet, and Global Positioning System/remote sensing to determine habitat selection and impact, have shown that herbivore communities are probably even more functionally diverse than currently realized. Moreover, although most diversity-function studies continue to emphasize plant diversity, herbivore diversity may have even stronger impacts on ecosystem multifunctionality. Recent studies also highlight the role of risk in plant-herbivore interactions, and risk-driven trophic cascades have emerged as landscape-scale patterns in a variety of ecosystems. Perhaps not surprisingly, many plant-herbivore interactions are currently being altered by climate change, which affects plant growth rates and resource allocation, expression of chemical defenses, plant phenology, and herbivore metabolism and behavior. Finally, we conclude by noting that although the field is advancing rapidly, the world is changing even more rapidly, challenging our ability to manage these pivotal links in the food chain.
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Lei, Boyu, Jifa Cui, Chris Newman, Christina D. Buesching, Zongqiang Xie, David W. Macdonald, and Youbing Zhou. "Seed dispersers shape the pulp nutrients of fleshy-fruited plants." Proceedings of the Royal Society B: Biological Sciences 288, no. 1953 (June 23, 2021): 20210817. http://dx.doi.org/10.1098/rspb.2021.0817.
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The dispersal-syndrome hypothesis posits that fruit traits are a product of selection by frugivores. Although criticized as adaptationist, recent studies have suggested that traits such as fruit or seed size, colour and odour exhibit signatures that imply selection by animal mutualists. These traits imply nutritional rewards (e.g. lipid, carbohydrate), attracting frugivores; however, this remains incompletely resolved. Here, we investigated whether fruit nutrients (lipid, sugar, protein, vitamin C, water content) moderate the co-adaptation of key disperser-group mutualisms. Multivariate techniques revealed that fruit nutrients assembled non-randomly and grouped according to key dispersal modes. Bird-dispersed fruits were richer in lipids than mammal-dispersed fruits. Mixed-dispersed fruits had significantly higher vitamin C than did mammal- or bird-dispersed fruits separately. Sugar and water content were consistently high irrespective of dispersal modes, suggesting that these traits appeal to both avian and mammalian frugivores to match high-energy requirements. Similarly, protein content was low irrespective of dispersal modes, corroborating that birds and mammals avoid protein-rich fruits, which are often associated with toxic levels of nitrogenous secondary compounds. Our results provide substantial over-arching evidence that seed disperser assemblages co-exert fundamental selection pressures on fruit nutrient trait adaptation, with broad implications for structuring fruit–frugivore mutualism and maintaining fruit trait diversity.
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Jacquemyn, Hans, and Rein Brys. "Lack of strong selection pressures maintains wide variation in floral traits in a food-deceptive orchid." Annals of Botany 126, no. 3 (April 25, 2020): 445–53. http://dx.doi.org/10.1093/aob/mcaa080.
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Abstract Background and Aims Angiosperms vary remarkably in traits such as colour, size and shape of flowers, yet such variation generally tends to be low within species. In deceptive orchids, however, large variation in floral traits has been described, not only between but also within populations. Nonetheless, the factors driving variation in floral traits in deceptive orchids remain largely unclear. Methods To identify determinants of variation in floral traits, we investigated patterns of fruit set and selection gradients in the food-deceptive orchid Orchis purpurea, which typically presents large within-population variation in the colour and size of the flowers. Using long-term data, fruit set was quantified in two populations over 16 consecutive years (2004–2019). Artificial hand pollination was performed to test the hypothesis that fruit set was pollinator-limited and that selfing led to decreased seed set and viability. Annual variation (2016–2019) in selection gradients was calculated for three colour traits (brightness, contrast and the number of spots on the labellum), flower size (spur length, labellum length and width) and plant size (number of flowers, plant height). Key Results Fruit set was, on average, low (~12 %) and severely pollinator-limited. Opportunities for selection varied strongly across years, but we found only weak evidence for selection on floral traits. In contrast, there was strong and consistent positive selection on floral display. Selfing led to reduced production of viable seeds and hence severe inbreeding depression (δ = 0.38). Conclusion Overall, these results demonstrate that the large variation in flower colour and size that is regularly observed in natural O. purpurea populations is maintained by the consistent lack of strong selection pressures on these traits through time.
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Huang, Xiaojuan, Minyu Chen, Linlin Wang, Mingliu Yang, Nacai Yang, Zhonghu Li, and Yuanwen Duan. "Phenotypic Selection in Halenia elliptica D. Don (Gentianaceae), an Alpine Biennial with Mixed Mating System." Plants 11, no. 11 (May 31, 2022): 1488. http://dx.doi.org/10.3390/plants11111488.
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The transition from outcrossing to selfing is a common evolutionary trend in flowering plants, and floral traits change significantly with the evolution of selfing. Whether or not plant traits are subjected to selection remains an open question in species with mixed mating systems. We examined phenotypic selection in two populations of Halenia elliptica with different selfing rates. We found that the pollen–ovule ratio, seed size, plant height, spur length, and pollinator visitation rate in the population with the higher selfing rate were lower than those in the population with the lower selfing rate. Selfing provides reproductive assurance for populations when pollinator service is low, and the floral traits that are associated with selfing syndrome are evident in populations with a higher selfing rate but are subjected to weak selection in each of the two populations with different selfing rates. Directional selection for an early flowering time indicated that late blooming flowers could experience a risk of seed development in alpine environments, and for large plants, selection indicated that seed production could be limited by the available resources. The floral traits that are associated with pollinator attraction and specialization could be subjected to weak selection at the plant level as selfing evolves, and the selective pressures that are independent of pollinators might not change significantly; highlighting the selective biotic and abiotic pressures that shape the morphological traits of plant species and their independence from the mating system.
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Neaux, Dimitri, Gabriele Sansalone, François Lecompte, Camille Noûs, Ashleigh Haruda, Renate Schafberg, and Thomas Cucchi. "Examining the effect of feralization on craniomandibular morphology in pigs, Sus scrofa (Artiodactyla: Suidae)." Biological Journal of the Linnean Society 131, no. 4 (November 16, 2020): 870–79. http://dx.doi.org/10.1093/biolinnean/blaa156.
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Abstract Feralization is the process by which domestic animals return to the wild and produce self-sustaining populations. It is often considered as a model in understanding the permanence of morphological changes associated with domestication; however, it is still unclear how much the release of anthropogenic selective pressures affects domestic traits. Here, we assessed the influence of feralization on the domestic morphological traits acquired through selective breeding using craniomandibular differences in shape and size between populations of feral pigs, wild boar and domestic pigs, using landmark-based geometric morphometrics. Our results suggest that numerous cranial and mandibular traits associated with domestication still exist in feral specimens, corroborating that domestication-induced changes in the shape of morphological elements are broadly maintained in feral populations. This is not the case for size variations, however, as the cranium is significantly smaller in feral pigs than in domesticated breeds, which could be due to the selective pressures associated with founding events. Our exploratory study, therefore, underlines the complexity of feral population history, the intricate influence of variations in genetic diversity, and novel selection pressures in the morphology of these groups. Future studies will need to expand the sample to take into account the diversity of morphotypes.
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Virgl, John A., Shane P. Mahoney, and Kim Mawhinney. "Phenotypic Variation in Skull Size and Shape Between Newfoundland and Mainland Populations of North American Black Bears, Ursus americanus." Canadian Field-Naturalist 117, no. 2 (April 1, 2003): 236. http://dx.doi.org/10.22621/cfn.v117i2.702.
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It is well recognized that differences in environmental selection pressures among populations can generate phenotypic divergence in a suite of morphological characteristics and associated life history traits. Previous analysis of mitochondrial DNA and body size have suggested that Black Bears (Ursus americanus) inhabiting the island of Newfoundland represent a different subspecies or ecotype from mainland populations. Assuming that body size covaries positively with skull size, we predicted that skull size would be greater for bears on the island than the mainland, and the distribution of size-related shape components in multivariate space should show a distinct separation between Newfoundland and mainland populations. Measurements of 1080 specimens from Newfoundland, Alberta, New York, and Quebec did not provide unequivocal support for our prediction that skull size in Newfoundland bears would be larger than bears from the mainland populations. After removing ontogenetic effects of skull size, between-population variation in skull shape was greater in females than males, and the analysis significantly separated Newfoundland bears from mainland populations. Explanations for this pattern are numerous, but currently remain hypothetical. Limited covariation between skull size and body size suggests that genetic traits regulating the size of Black Bear skulls are more heritable (i.e., less influenced by environmental selection pressures) than characteristics affecting body size. We hypothesize that if gape size does not limit prey size in solitary terrestrial carnivores, large degrees of among-population variation in body size should be coupled with little covariation in skull size. In general, sexual dimorphism in skull size and shape was marginal for the phenotypic characters measured in our study. We believe that sexual dimorphism in skull size in Black Bears is primarily driven by intrasexual selection in males for increased gape size display, while similarity in skull shape between sexes is associated with the constraints of a temporally-selective, but similar diet.
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Taylor-Cox, Evelyn D., Callum J. Macgregor, Amy Corthine, Jane K. Hill, Jenny A. Hodgson, and Ilik J. Saccheri. "Wing morphological responses to latitude and colonisation in a range expanding butterfly." PeerJ 8 (November 19, 2020): e10352. http://dx.doi.org/10.7717/peerj.10352.
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Populations undergoing rapid climate-driven range expansion experience distinct selection regimes dominated both by increased dispersal at the leading edges and steep environmental gradients. Characterisation of traits associated with such expansions provides insight into the selection pressures and evolutionary constraints that shape demographic and evolutionary responses. Here we investigate patterns in three components of wing morphology (size, shape, colour) often linked to dispersal ability and thermoregulation, along latitudinal gradients of range expansion in the Speckled Wood butterfly (Pararge aegeria) in Britain (two regions of expansion in England and Scotland). We measured 774 males from 54 sites spanning 799 km with a 10-year mean average temperature gradient of 4 °C. A geometric morphometric method was used to investigate variation in size and shape of forewings and hindwings; colour, pattern, and contrast of the wings were examined using a measure of lightness (inverse degree of melanism). Overall, wing size increased with latitude by ∼2% per 100 km, consistent with Bergmann’s rule. Forewings became more rounded and hindwings more elongated with history of colonisation, possibly reflecting selection for increased dispersal ability. Contrary to thermal melanism expectations, wing colour was lighter where larvae developed at cooler temperatures and unrelated to long-term temperature. Changes in wing spot pattern were also detected. High heterogeneity in variance among sites for all of the traits studied may reflect evolutionary time-lags and genetic drift due to colonisation of new habitats. Our study suggests that temperature-sensitive plastic responses for size and colour interact with selection for dispersal traits (wing size and shape). Whilst the plastic and evolutionary responses may in some cases act antagonistically, the rapid expansion of P. aegeria implies an overall reinforcing effect between these two mechanisms.
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Borczyk, Bartosz, Jan Kusznierz, Łukasz Paśko, and Edyta Turniak. "Scaling of the sexual size and shape skull dimorphism in the sand lizard (Lacerta agilis L.)." Vertebrate Zoology 64, no. 2 (July 15, 2014): 221–27. http://dx.doi.org/10.3897/vz.64.e31484.
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Sand lizards (Lacerta agilis) exhibit a clear pattern of sexual dimorphism, both in coloration and body proportions, where males have larger heads and are longer-legged at a given snout-to-vent length (SVL). In this study we analyse allometry of skull growth with SVL and skull length (SL) as references. The sand lizard skull is basically sexually size dimorphic and there are only minor shape differences. When SVL is used as a reference point, it generates differences in all traits to be measured, presumably because SVL is subject to different and strong selection pressures in both sexes. When skull length is taken as a reference point, differences in skull shape are restricted only to the postorbital region, which is wider in males. This may reflect selection pressure on stronger bite force in males.
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Andersson, Stefan. "Phenotypic selection in a population of Crepis tectorum ssp. pumila (Asteraceae)." Canadian Journal of Botany 70, no. 1 (January 1, 1992): 89–95. http://dx.doi.org/10.1139/b92-012.
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A 3-year demographic study was conducted to reveal targets of selection on morphology and life history in a population of Crepis tectorum ssp. pumila, a winter annual plant confined to calcareous grasslands (alvars) on the Baltic island of Öland (south Sweden). I calculated the selection differential to describe the change in the mean value of a character due to selection and used multiple regression analyses to partition the direct effect of selection on the trait from indirect responses of selection on other traits. Rosette leaf number, a convenient measure of plant size, was strongly correlated with both viability and fertility (fitness). There was also a strong relationship between fitness and the extent to which the plants expressed traits characterizing this particular taxon. Multiple regression analyses indicated direct selection favouring plants with deeply lobed leaves and a densely branched stem, two distinctive traits of ssp. pumila believed to be adaptive in the alvar habitat. Only stem height was subject to both direct and indirect selection in the wrong direction; taller individuals were more successful than those with a shorter stem, a surprising result considering the inferred advantage of a short stature in the exposed alvar habitat. Selection on other traits assumed to be ecologically important (germination time, flowering time, and seed size) was found to be either absent or variable in direction when other traits were held constant. The failure of plants to survive to the flowering stage in the last two summers indicates strong selection for plants that produce a high percentage of dormant seeds. Overall, the contemporary selection regime as revealed by demographic data was only partly congruent with predictions regarding historical selection pressures based on large-scale patterns of variation (ecotypic differentiation). Key words: Crepis tectorum, ecotypic differentiation, life history, morphology, phenotypic selection.
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Spottiswoode, Claire N. "A brood parasite selects for its own egg traits." Biology Letters 9, no. 5 (October 23, 2013): 20130573. http://dx.doi.org/10.1098/rsbl.2013.0573.
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Many brood parasitic birds lay eggs that mimic their hosts' eggs in appearance. This typically arises from selection from discriminating hosts that reject eggs which differ from their own. However, selection on parasitic eggs may also arise from parasites themselves, because it should pay a laying parasitic female to detect and destroy another parasitic egg previously laid in the same host nest by a different female. In this study, I experimentally test the source of selection on greater honeyguide ( Indicator indicator ) egg size and shape, which is correlated with that of its several host species, all of which breed in dark holes. Its commonest host species did not discriminate against experimental eggs that differed from their own in size and shape, but laying female honeyguides preferentially punctured experimental eggs more than host or control eggs. This should improve offspring survival given that multiple parasitism by this species is common, and that honeyguide chicks kill all other nest occupants. Hence, selection on egg size in greater honeyguides parasitizing bee-eaters appears to be imposed not by host defences but by interference competition among parasites themselves.
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Oliveira, Larissa C., Alberto L. Teixido, Renata Trevizan, and Vinícius L. G. Brito. "Bee-Mediated Selection Favors Floral Sex Specialization in a Heterantherous Species: Strategies to Solve the Pollen Dilemma." Plants 9, no. 12 (December 1, 2020): 1685. http://dx.doi.org/10.3390/plants9121685.
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Animal-pollinated plants show a broad variation in floral morphology traits and gametophyte production within populations. Thus, floral traits related to plant reproduction and sexuality are usually exposed to pollinator-mediated selection. Such selective pressures may be even stronger in heterantherous and pollen flowers, in which pollen contributes to both bee feeding and pollination, overcoming the “pollen dilemma” or the inability to perform both functions simultaneously. We describe the phenotypic gender and sexual organ morphology of flowers in two populations of Macairea radula (Melastomataceae), a heterantherous and buzz-pollinated species with pollen flowers. We estimated selection gradients on these traits through female and male fitness components. Both populations showed sizeable phenotypic gender variation, from strict hermaphrodites to increased femaleness or maleness. We found a continuous variation in style and stamen size, and this variation was correlated with corresponding shape values of both sexual organs. We detected bee-mediated selection towards short and long styles through seed number and towards intermediate degrees of heteranthery through pollen removal in one population, and selection towards increased maleness through pollen dispersal in both populations. Our results suggest that bee-mediated selection favors floral sex specialization and stylar dimorphism in M. radula, optimizing reproductive success and solving the pollen dilemma.
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Luby, James J., and Douglas V. Shaw. "Plant Breeders' Perspectives on Improving Yield and Quality Traits in Horticultural Food Crops." HortScience 44, no. 1 (February 2009): 20–22. http://dx.doi.org/10.21273/hortsci.44.1.20.
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Breeders of horticultural food crops are usually concerned with multiple traits related to yield and quality as well as other traits such as biotic and abiotic stresses. Yield in these crops is not solely tonnage of biomass produced in the field. Rather, it is the proportion of the crop that can be harvested and brought to market in a condition and at a price acceptable to the consumer. Quality may include flavor, color, shape, size, degree of damage, nutrient levels, and traits that permit greater perceived food safety or environmental sustainability. Some traits may exhibit phenotypic associations. Traits with unfavorable associations will be of concern to the breeder if the cause is unfavorably correlated genetic effects, especially those resulting from pleiotropy. Several multiple trait selection schemes have been developed, including independent culling levels, tandem selection, and index selection. These schemes can result in improvement even for traits with unfavorable associations. However, the breeder must have a strong rationale for each trait addressed in a breeding program because each additional trait necessitates larger breeding populations and more resources. Thus, the breeder's first challenge for each crop is to determine which traits are most important and which issues are most amenable to a breeding solution.
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Evans, Jonathan P., Clelia Gasparini, Gregory I. Holwell, Indar W. Ramnarine, Trevor E. Pitcher, and Andrea Pilastro. "Intraspecific evidence from guppies for correlated patterns of male and female genital trait diversification." Proceedings of the Royal Society B: Biological Sciences 278, no. 1718 (January 26, 2011): 2611–20. http://dx.doi.org/10.1098/rspb.2010.2453.
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The role of sexual selection in fuelling genital evolution is becoming increasingly apparent from comparative studies revealing interspecific divergence in male genitalia and evolutionary associations between male and female genital traits. Despite this, we know little about intraspecific variance in male genital morphology, or how male and female reproductive traits covary among divergent populations. Here we address both topics using natural populations of the guppy, Poecilia reticulata , a livebearing fish that exhibits divergent patterns of male sexual behaviour among populations. Initially, we performed a series of mating trials on a single population to examine the relationship between the morphology of the male's copulatory organ (the gonopodium) and the success of forced matings. Using a combination of linear measurements and geometric morphometrics, we found that variation in the length and shape of the gonopodium predicted the success of forced matings in terms of the rate of genital contacts and insemination success, respectively. We then looked for geographical divergence in these traits, since the relative frequency of forced matings tends to be greater in high-predation populations. We found consistent patterns of variation in male genital size and shape in relation to the level of predation, and corresponding patterns of (co)variation in female genital morphology. Together, these data enable us to draw tentative conclusions about the underlying selective pressures causing correlated patterns of divergence in male and female genital traits, which point to a role for sexually antagonistic selection.
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Busschau, Theo, and Stephane Boissinot. "Habitat determines convergent evolution of cephalic horns in vipers." Biological Journal of the Linnean Society 135, no. 4 (March 1, 2022): 652–64. http://dx.doi.org/10.1093/biolinnean/blac008.
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Abstract Phenotypic convergence of traits in similar environments can provide insights into the evolutionary processes shaping trait evolution. Among squamate reptiles, horn-like cephalic appendages have evolved under various selective pressures, including selection for defence, crypsis or sexual selection. Yet, among snakes, particularly vipers, the functional and evolutionary significance of horns are unknown. We used a comparative phylogenetic approach with habitat and diet data on 263 viper taxa to shed light on the selective pressures underlying horn evolution in vipers. We detected significant correlations with habitat but not diet. The relative positions of horns are ecologically divergent in that supranasal horns are positively correlated with terrestrial forest habitats while supraocular horns are negatively correlated with terrestrial forest habitats and are instead associated with arboreal or sparsely vegetated habitats. Multiple independent origins of supranasal or supraocular horns in similar habitats provide evidence of adaptive convergence. Comparisons with other snake lineages suggest that cephalic appendages may have evolved under selection for crypsis in ambush foraging snakes.
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Fowler-Finn, Kasey D., Emilia Triana, and Owen G. Miller. "Mating in the harvestman Leiobunum vittatum (Arachnida: Opiliones): from premating struggles to solicitous tactile engagement." Behaviour 151, no. 12-13 (2014): 1663–86. http://dx.doi.org/10.1163/1568539x-00003209.
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When mating interactions are influenced by multiple sources of selection, they may involve multiple stages of mate assessment. At each stage, a different set of morphological and behavioural traits may be important in determining the outcome of the interaction. Here, we test the potential for multiple sources of selection to shape mating interactions in Leiobunum vittatum harvestmen, commonly known as ‘daddy longlegs’. We provide a qualitative and quantitative study of mating interactions, and investigate the influence of multiple morphological traits on each of several distinct stages of their mating interactions. Mating interactions start with a struggle between males and females during which the male attempts to secure the females in a mating embrace. Success at this stage depends on the length of the male’s clasping pedipalps: those with shorter pedipalps (and thus greater mechanical advantage) were more successful. Male size relative to the female determines how quickly males achieve this embrace. Mating interactions then proceed to tactile exchanges between males and females, indicating the potential for mutual mate choice and/or peri- and post-copulatory selection. We found no morphological predictors of the timing of these later stages of the mating interactions, and suggest that the exchange of a nuptial gift is important for the dynamics of these stages. Overall, our results highlight L. vittatum as a potentially highly informative group for studying how traits involved in mating are shaped by the interaction of selection across multiple stages in mating interactions.
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Morris, Jeremy S., Nala Rogers, Alan R. Rogers, and David R. Carrier. "Sexual dimorphism in skeletal shape in voles (Arvicolinae): disparate selection on male bodies and female heads." Journal of Mammalogy 101, no. 4 (July 23, 2020): 951–57. http://dx.doi.org/10.1093/jmammal/gyaa076.
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Abstract Sexual dimorphism evolves as a response to different selective pressures on males and females. In mammals, sexual selection on traits that improve a male’s ability to compete for access to mates is a common cause of sexual dimorphism. In addition to body mass, adaptations in specific components of the musculoskeletal system that increase strength, stability, and agility, may improve male fighting performance. Here we test the hypotheses that males, when compared to females, are more specialized for physical competition in their skeletal anatomy and that the degree of this sexual dimorphism increases with the intensity of male–male competition. In three species of voles (Cricetidae: Arvicolinae: Microtus), we found partial support for these hypotheses. Male-biased sexual dimorphism in a set of functional indices associated with improved fighting performance was identified in the postcranial anatomy. This dimorphism was greatest in the polygynous Microtus californicus, absent in the monogamous M. ochrogaster, and intermediate in the promiscuous or socially flexible M. oeconomus. However, in the skull, we found results opposite to our predictions. Females had larger skulls relative to overall skeletal size than did males. This may be associated with selection for increased food processing efficiency, which should be highly important because of the compounding effects of increased caloric requirements during gestation and lactation, and the generally low-quality diet of voles. In addition, larger heads in females may be associated with selection for greater digging ability or for defending offspring. These results suggest disparate selective pressures on the postcranial skeletons and skulls of male and female voles.
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Jones, Alfred. "BREEDING SWEETPOTATO FOR RESISTANCE TO MULTIPLE INSECT PESTS." HortScience 25, no. 9 (September 1990): 1177G—1178. http://dx.doi.org/10.21273/hortsci.25.9.1177.
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Sweetpotato [Ipomoea batatas (L.) Lam.] cultivars with high levels of resistance to root damaging insects have been developed through the collaborative efforts of a multidisciplinary research team. These resistances were combined with other traits necessary for a successful cultivar such as: disease resistances; high yield; long storage life; prolific sprout production; marketable root size, shape and skin at tributes; and culinary excellence. Adpotion of quantitative genetic principles, development of a wide gene base, sequential selection schemes, use of effective selection criteria and appropriate susceptible standards contributed to the program's success. These achievements were made with, little prior knowledge about inheritance patterns, gene action, mechanisms of resistance or a complete knowledge of the insects concerned. The value of insect resistant cultivars has become better appreciated with the recent decrease in chemical alternatives.
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Jones, Alfred. "BREEDING SWEETPOTATO FOR RESISTANCE TO MULTIPLE INSECT PESTS." HortScience 25, no. 9 (September 1990): 1177g—1178. http://dx.doi.org/10.21273/hortsci.25.9.1177g.
Full textAbstract:
Sweetpotato [Ipomoea batatas (L.) Lam.] cultivars with high levels of resistance to root damaging insects have been developed through the collaborative efforts of a multidisciplinary research team. These resistances were combined with other traits necessary for a successful cultivar such as: disease resistances; high yield; long storage life; prolific sprout production; marketable root size, shape and skin at tributes; and culinary excellence. Adpotion of quantitative genetic principles, development of a wide gene base, sequential selection schemes, use of effective selection criteria and appropriate susceptible standards contributed to the program's success. These achievements were made with, little prior knowledge about inheritance patterns, gene action, mechanisms of resistance or a complete knowledge of the insects concerned. The value of insect resistant cultivars has become better appreciated with the recent decrease in chemical alternatives.
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Angelini, Claudio, Francesca Antonucci, Jacopo Aguzzi, and Corrado Costa. "Different Traits, Different Evolutionary Pathways: Insights from Salamandrina (Amphibia, Caudata)." Animals 12, no. 23 (November 28, 2022): 3326. http://dx.doi.org/10.3390/ani12233326.
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Species delimitation is often based on a single or very few genetic or phenetic traits, something which leads to misinterpretations and often does not provide information about evolutionary processes. Here, we investigated the diversity pattern of multiple phenetic traits of the two extant species of Salamandrina, a genus split only after molecular traits had been studied but the two species of which are phenetically very similar. The phenetic traits we studied are size, external body shape and head colour pattern, in a model comparison framework using non-linear mixed models and unsupervised and supervised clustering. Overall, we found high levels of intra-specific variability for body size and shape, depending on population belonging and habitat, while differences between species were generally lower. The habitat the salamanders dwell in also seems important for colour pattern. Basing on our findings, from the methodological point of view, we suggest (i) to take into account the variability at population level when testing for higher level variability, and (ii) a semi-supervised learning approach to high dimensional data. We also showed that different phenotypic traits of the same organism could result from different evolutionary routes. Local adaptation is likely responsible for body size and shape variability, with selective pressures more similar across species than within them. Head colour pattern also depends on habitat, differently from ventral colour pattern (not studied in this paper) which likely evolved under genetic drift.
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Sork, Victoria L., Paul F. Gugger, Jin-Ming Chen, and Silke Werth. "Evolutionary lessons from California plant phylogeography." Proceedings of the National Academy of Sciences 113, no. 29 (July 18, 2016): 8064–71. http://dx.doi.org/10.1073/pnas.1602675113.
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Phylogeography documents the spatial distribution of genetic lineages that result from demographic processes, such as population expansion, population contraction, and gene movement, shaped by climate fluctuations and the physical landscape. Because most phylogeographic studies have used neutral markers, the role of selection may have been undervalued. In this paper, we contend that plants provide a useful evolutionary lesson about the impact of selection on spatial patterns of neutral genetic variation, when the environment affects which individuals can colonize new sites, and on adaptive genetic variation, when environmental heterogeneity creates divergence at specific loci underlying local adaptation. Specifically, we discuss five characteristics found in plants that intensify the impact of selection: sessile growth form, high reproductive output, leptokurtic dispersal, isolation by environment, and the potential to evolve longevity. Collectively, these traits exacerbate the impact of environment on movement between populations and local selection pressures—both of which influence phylogeographic structure. We illustrate how these unique traits shape these processes with case studies of the California endemic oak, Quercus lobata, and the western North American lichen, Ramalina menziesii. Obviously, the lessons we learn from plant traits are not unique to plants, but they highlight the need for future animal, plant, and microbe studies to incorporate its impact. Modern tools that generate genome-wide sequence data are now allowing us to decipher how evolutionary processes affect the spatial distribution of different kinds of genes and also to better model future spatial distribution of species in response to climate change.
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McLean, Callum J., Russell J. Garwood, and Charlotte A. Brassey. "Sexual dimorphism in the Arachnid orders." PeerJ 6 (November 6, 2018): e5751. http://dx.doi.org/10.7717/peerj.5751.
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Sexual differences in size and shape are common across the animal kingdom. The study of sexual dimorphism (SD) can provide insight into the sexual- and natural-selection pressures experienced by males and females in different species. Arachnids are diverse, comprising over 100,000 species, and exhibit some of the more extreme forms of SD in the animal kingdom, with the males and females of some species differing dramatically in body shape and/or size. Despite this, research on arachnid SD has primarily focused on specific clades as opposed to observing traits across arachnid orders, the smallest of which have received comparatively little attention. This review provides an overview of the research to date on the trends and potential evolutionary drivers for SD and sexual size dimorphism (SSD) in individual arachnid orders, and across arachnids as a whole. The most common trends across Arachnida are female-biased SSD in total body size, male-biased SSD in relative leg length and SD in pedipalp length and shape. However, the evolution of sexually dimorphic traits within the group is difficult to elucidate due to uncertainty in arachnid phylogenetic relationships. Based on the dataset we have gathered here, we highlight gaps in our current understanding and suggest areas for future research.
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Cai, Feng, Renwei Gao, Zheng Zhao, Mingyue Ding, Siqi Jiang, Civan Yagtu, Hong Zhu, et al. "Evolutionary compromises in fungal fitness: hydrophobins can hinder the adverse dispersal of conidiospores and challenge their survival." ISME Journal 14, no. 10 (July 6, 2020): 2610–24. http://dx.doi.org/10.1038/s41396-020-0709-0.
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Abstract Fungal evolutionary biology is impeded by the scarcity of fossils, irregular life cycles, immortality, and frequent asexual reproduction. Simple and diminutive bodies of fungi develop inside a substrate and have exceptional metabolic and ecological plasticity, which hinders species delimitation. However, the unique fungal traits can shed light on evolutionary forces that shape the environmental adaptations of these taxa. Higher filamentous fungi that disperse through aerial spores produce amphiphilic and highly surface-active proteins called hydrophobins (HFBs), which coat spores and mediate environmental interactions. We exploited a library of HFB-deficient mutants for two cryptic species of mycoparasitic and saprotrophic fungi from the genus Trichoderma (Hypocreales) and estimated fungal development, reproductive potential, and stress resistance. HFB4 and HFB10 were found to be relevant for Trichoderma fitness because they could impact the spore-mediated dispersal processes and control other fitness traits. An analysis in silico revealed purifying selection for all cases except for HFB4 from T. harzianum, which evolved under strong positive selection pressure. Interestingly, the deletion of the hfb4 gene in T. harzianum considerably increased its fitness-related traits. Conversely, the deletion of hfb4 in T. guizhouense led to the characteristic phenotypes associated with relatively low fitness. The net contribution of the hfb4 gene to fitness was found to result from evolutionary tradeoffs between individual traits. Our analysis of HFB-dependent fitness traits has provided an evolutionary snapshot of the selective pressures and speciation process in closely related fungal species.
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Koskella, Britt, and Tiffany B. Taylor. "Multifaceted Impacts of Bacteriophages in the Plant Microbiome." Annual Review of Phytopathology 56, no. 1 (August 25, 2018): 361–80. http://dx.doi.org/10.1146/annurev-phyto-080417-045858.
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Plant-associated bacteria face multiple selection pressures within their environments and have evolved countless adaptations that both depend on and shape bacterial phenotype and their interaction with plant hosts. Explaining bacterial adaptation and evolution therefore requires considering each of these forces independently as well as their interactions. In this review, we examine how bacteriophage viruses (phages) can alter the ecology and evolution of plant-associated bacterial populations and communities. This includes influencing a bacterial population's response to both abiotic and biotic selection pressures and altering ecological interactions within the microbiome and between the bacteria and host plant. We outline specific ways in which phages can alter bacterial phenotype and discuss when and how this might impact plant-microbe interactions, including for plant pathogens. Finally, we highlight key open questions in phage-bacteria-plant research and offer suggestions for future study.
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Benítez, Hugo A., Raisa A. Sukhodolskaya, Rodrigo Órdenes-Clavería, Tamara A. Avtaeva, Shapaat A. Kushalieva, and Anatoly A. Saveliev. "Measuring the Inter and Intraspecific Sexual Shape Dimorphism and Body Shape Variation in Generalist Ground Beetles in Russia." Insects 11, no. 6 (June 10, 2020): 361. http://dx.doi.org/10.3390/insects11060361.
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Ground beetles in multiple species vary greatly in the expression of the shape on sexual traits, resulting in a sexual shape dimorphism as a consequence of sexual selection differences. The present research focuses on the study of inter and intrasexual sexual shape dimorphism of two generalist genera of ground beetles Pterostichus and Carabus. Geometric morphometric methods were applied to five generalist species of ground beetles Carabus exaratus, C. granulatus, Pterostichus melanarius, P. niger, and P. oblongopunctatus and several multivariate analyses were applied for two different traits, abdomen and elytra. Three of the five species analyzed showed high levels of sex-based shape dimorphism. However, the most generalist species, P. melanarius and P. oblongopunctatus, did not evidence shape-based sexual dimorphism differentiation in both of the analyzed traits, as statistically confirmed based on the permutation of pairwise comparison of the Mahalanobis distances of a sex–species classifier. It is generally known that environmental stress in natural populations can affect the fitness expression, principally related to sexual fecundity, being that this pattern is more evident in non-generalist species. In our results, the contrary pattern was found, with the absence of sexual shape dimorphism for two of the three generalist species analyzed. On the other hand, the interspecies shape variation was clearly identified using principal component analysis of both of the analyzed traits. Finally, this research is the first to analyze the relationship between sexual shape dimorphism in Russian ground beetles, evidencing the lack of understanding of the mechanism underlying the sexual dimorphism, especially in species living in extreme environments.
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Doganlar, Sami, Anne Frary, Marie-Christine Daunay, Richard N. Lester, and Steven D. Tanksley. "Conservation of Gene Function in the Solanaceae as Revealed by Comparative Mapping of Domestication Traits in Eggplant." Genetics 161, no. 4 (August 1, 2002): 1713–26. http://dx.doi.org/10.1093/genetics/161.4.1713.
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Abstract Quantitative trait loci (QTL) for domestication-related traits were identified in an interspecific F2 population of eggplant (Solanum linnaeanum × S. melongena). Although 62 quantitative trait loci (QTL) were identified in two locations, most of the dramatic phenotypic differences in fruit weight, shape, color, and plant prickliness that distinguish cultivated eggplant from its wild relative could be attributed to six loci with major effects. Comparison of the genomic locations of the eggplant fruit weight, fruit shape, and color QTL with the positions of similar loci in tomato, potato, and pepper revealed that 40% of the different loci have putative orthologous counterparts in at least one of these other crop species. Overall, the results suggest that domestication of the Solanaceae has been driven by mutations in a very limited number of target loci with major phenotypic effects, that selection pressures were exerted on the same loci despite the crops' independent domestications on different continents, and that the morphological diversity of these four crops can be explained by divergent mutations at these loci.
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García-González, Carlos A., and Cristina Silvar. "Phytochemical Assessment of Native Ecuadorian Peppers (Capsicum spp.) and Correlation Analysis to Fruit Phenomics." Plants 9, no. 8 (August 4, 2020): 986. http://dx.doi.org/10.3390/plants9080986.
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In this work, the impact of pepper (Capsicum spp.) fruits morphology on their composition for health-promoting compounds was investigated. For that purpose, pepper accessions from Ecuador, one of the hotspots in Capsicum’s origin, were analyzed for ascorbic acid, polyphenols, capsaicinoids, and prevention of cholesterol oxidation. Plant and fruit phenomics were assessed with conventional descriptors and Tomato Analyzer digital traits. Significant differences among accessions and species revealed a large diversity within the collection. The Capsicum frutescens group displayed the highest levels of capsaicinoids, whereas the polyphenols shortly varied among the five domesticated species. Capsicum pubescens exhibited the lowest content of ascorbic acid. The conventional descriptors describing the magnitude of plants and fruits, as well as digital attributes under the categories of size, shape index, and latitudinal section, mostly explained the variance among Capsicum groups. Correlation test revealed that phytochemical components were negatively correlated with the morphometric fruit attributes, suggesting that huge fruits contained lower amounts of nutraceutical compounds. Multivariate analysis showed that parameters related to fruit size, shape, and nutraceutical composition primarily contribute to the arrangement of pepper accessions. Such results suggested that those traits have been subjected to higher selection pressures imposed by humans.
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Whitaker, Vance M., Luis F. Osorio, Tomas Hasing, and Salvador Gezan. "Estimation of Genetic Parameters for 12 Fruit and Vegetative Traits in the University of Florida Strawberry Breeding Population." Journal of the American Society for Horticultural Science 137, no. 5 (September 2012): 316–24. http://dx.doi.org/10.21273/jashs.137.5.316.
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The University of Florida strawberry (Fragaria ×ananassa) breeding population has been continuously improved by recurrent selection since 1968. However, there is a lack of information on genetic parameters that may inform breeding decisions. Parameters were estimated in this population using 19 full-sib families from a 5 × 4 factorial mating design plus six additional biparental crosses and 14 control genotypes including some of the parents. During the 2010–11 season, clonal replicates of the seedling and parental genotypes were distributed within and among two field locations in west–central Florida. Twelve commercially important traits were measured including fruit chemical traits (soluble solids content and titratable acidity), other fruit and yield traits (early and total marketable yields, proportion of total cull fruit, proportion of misshapen fruit, proportion water-damaged fruit, and shape score), and vegetative traits (plant height and total runners). Heritabilities, genotype by environment interaction, and multiple correlations (phenotypic, genotypic, and genetic) were estimated using general mixed model analyses. Narrow-sense heritabilities varied from low to moderate (h2 = 0.13 ± 0.07 to 0.32 ± 0.09) except for shape score (h2 = 0.06 ± 0.04) and total average weight (h2 = 0.52 ± 0.07). Broad-sense heritabilities were larger (H2 = 0.18 ± 0.03 to 0.53 ± 0.04), and for more than half of the traits, over 50% of the total genetic variation was non-additive. Large genetic and genotypic correlations were found for some traits, most notably between soluble solids content and early marketable yield (–0.68 ± 0.22). Genetic gains for this pair of traits based on a Monte Carlo simulation illustrated the tradeoff between these two traits, showing that a 27% increase in early yield could be obtained through selection but at the expense of an 8% decrease in soluble solids. However, moderate gains can be made in both traits using the appropriate index coefficients.
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Chira, A. M., C. R. Cooney, J. A. Bright, E. J. R. Capp, E. C. Hughes, C. J. A. Moody, L. O. Nouri, Z. K. Varley, and G. H. Thomas. "The signature of competition in ecomorphological traits across the avian radiation." Proceedings of the Royal Society B: Biological Sciences 287, no. 1938 (November 11, 2020): 20201585. http://dx.doi.org/10.1098/rspb.2020.1585.
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Competition for shared resources represents a fundamental driver of biological diversity. However, the tempo and mode of phenotypic evolution in deep-time has been predominantly investigated using trait evolutionary models which assume that lineages evolve independently from each other. Consequently, the role of species interactions in driving macroevolutionary dynamics remains poorly understood. Here, we quantify the prevalence for signatures of competition between related species in the evolution of ecomorphological traits across the bird radiation. We find that mechanistic trait models accounting for the effect of species interactions on phenotypic divergence provide the best fit for the data on at least one trait axis in 27 out of 59 clades ranging between 21 and 195 species. Where it occurs, the signature of competition generally coincides with positive species diversity-dependence, driven by the accumulation of lineages with similar ecologies, and we find scarce evidence for trait-dependent or negative diversity-dependent phenotypic evolution. Overall, our results suggest that the footprint of interspecific competition is often eroded in long-term patterns of phenotypic diversification, and that other selection pressures may predominantly shape ecomorphological diversity among extant species at macroevolutionary scales.
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Shenhav, Liat, and David Zeevi. "Resource conservation manifests in the genetic code." Science 370, no. 6517 (November 5, 2020): 683–87. http://dx.doi.org/10.1126/science.aaz9642.
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Nutrient limitation drives competition for resources across organisms. However, much is unknown about how selective pressures resulting from nutrient limitation shape microbial coding sequences. Here, we study this “resource-driven selection” by using metagenomic and single-cell data of marine microbes, alongside environmental measurements. We show that a significant portion of the selection exerted on microbes is explained by the environment and is associated with nitrogen availability. Notably, this resource conservation optimization is encoded in the structure of the standard genetic code, providing robustness against mutations that increase carbon and nitrogen incorporation into protein sequences. This robustness generalizes to codon choices from multiple taxa across all domains of life, including the human genome.
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Gomez, Kevin, Jason Bertram, and Joanna Masel. "Mutation bias can shape adaptation in large asexual populations experiencing clonal interference." Proceedings of the Royal Society B: Biological Sciences 287, no. 1937 (October 21, 2020): 20201503. http://dx.doi.org/10.1098/rspb.2020.1503.
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The extended evolutionary synthesis invokes a role for development in shaping adaptive evolution, which in population genetics terms corresponds to mutation-biased adaptation. Critics have claimed that clonal interference makes mutation-biased adaptation rare. We consider the behaviour of two simultaneously adapting traits, one with larger mutation rate U , the other with larger selection coefficient s , using asexual travelling wave models. We find that adaptation is dominated by whichever trait has the faster rate of adaptation v in isolation, with the other trait subject to evolutionary stalling. Reviewing empirical claims for mutation-biased adaptation, we find that not all occur in the ‘origin-fixation’ regime of population genetics where v is only twice as sensitive to s as to U . In some cases, differences in U are at least ten to twelve times larger than differences in s , as needed to cause mutation-biased adaptation even in the ‘multiple mutations’ regime. Surprisingly, when U > s in the ‘diffusive-mutation’ regime, the required sensitivity ratio is also only two, despite pervasive clonal interference. Given two traits with identical v , the benefit of having higher s is surprisingly small, occurring largely when one trait is at the boundary between the origin-fixation and multiple mutations regimes.
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Brainard, Scott H., Shelby L. Ellison, Philipp W. Simon, Julie C. Dawson, and Irwin L. Goldman. "Genetic characterization of carrot root shape and size using genome-wide association analysis and genomic-estimated breeding values." Theoretical and Applied Genetics 135, no. 2 (November 15, 2021): 605–22. http://dx.doi.org/10.1007/s00122-021-03988-8.
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Abstract Key message The principal phenotypic determinants of market class in carrot—the size and shape of the root—are under primarily additive, but also highly polygenic, genetic control. Abstract The size and shape of carrot roots are the primary determinants not only of yield, but also market class. These quantitative phenotypes have historically been challenging to objectively evaluate, and thus subjective visual assessment of market class remains the primary method by which selection for these traits is performed. However, advancements in digital image analysis have recently made possible the high-throughput quantification of size and shape attributes. It is therefore now feasible to utilize modern methods of genetic analysis to investigate the genetic control of root morphology. To this end, this study utilized both genome wide association analysis (GWAS) and genomic-estimated breeding values (GEBVs) and demonstrated that the components of market class are highly polygenic traits, likely under the influence of many small effect QTL. Relatively large proportions of additive genetic variance for many of the component phenotypes support high predictive ability of GEBVs; average prediction ability across underlying market class traits was 0.67. GWAS identified multiple QTL for four of the phenotypes which compose market class: length, aspect ratio, maximum width, and root fill, a previously uncharacterized trait which represents the size-independent portion of carrot root shape. By combining digital image analysis with GWAS and GEBVs, this study represents a novel advance in our understanding of the genetic control of market class in carrot. The immediate practical utility and viability of genomic selection for carrot market class is also described, and concrete guidelines for the design of training populations are provided.
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Simpson, Richard K., Allison F. Mistakidis, and Stéphanie M. Doucet. "Natural and sexual selection shape the evolution of colour and conspicuousness in North American wood-warblers (Parulidae)." Biological Journal of the Linnean Society 130, no. 1 (March 10, 2020): 89–100. http://dx.doi.org/10.1093/biolinnean/blaa015.
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Abstract Natural and sexual selection drive colour evolution in animals. However, these different selective forces are often studied independently or without considering environmental variation. We evaluated the roles of natural and sexual selection together on colour evolution in 15 sympatric wood-warbler species, while considering the influence of variation in the light environment and visual background. We tested the influence of each selective pressure on male and female coloration and contrast against the background using avian visual models in phylogenetically controlled analyses. We found natural and sexual selection simultaneously driving cryptic and conspicuous plumage in males by acting on different body regions. For example, we found that ground-nesting species had males with conspicuous under-body plumage and cryptic upper-body plumage, showing how natural and sexual selection can drive colour evolution concordantly. We also found interesting relationships with female plumage, such as nest predation positively covarying with female contrast against the background, suggesting a cost to female conspicuousness. Our findings here showcase the complexity of selection on coloration and illustrate the importance of: (1) accounting for environmental variation when assessing how natural and sexual selection drive colour evolution; and (2) testing how multiple selection pressures are shaping colour diversity among species.
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Naretto, S., and M. Chiaraviglio. "Factors driving sexual dimorphism and colour variability in the Achala Copper Lizard (Pristidactylus achalensis), an endemic species to the highland mountains in central Argentina." Canadian Journal of Zoology 98, no. 6 (June 2020): 377–89. http://dx.doi.org/10.1139/cjz-2019-0293.
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The intensity of mating competition varies according to the temporal and spatial distribution of individuals. Measuring sexual dimorphism over time and interpreting the association between individuals is therefore important if we aim to understand how sexual traits are influenced. We examined sex differences in the Achala Copper Lizard (Pristidactylus achalensis (Gallardo, 1964)), an endemic species from the highest part of mountains of central Argentina. Over 4 years, we explored sex-specific variation in body size, head size, interlimb length, and body colouration. Furthermore, we evaluated how these traits varied temporally, and we also explored whether the spatial distribution of individuals is explained by variation in these traits. We found that P. achalensis is a species with sexual dimorphism in multiple characters, including body size, head size, and colouration. Interestingly, some traits related to mating, such as head width, show a temporal variability in both sexes, whereas other traits, such as colouration, varies seasonally only in males. Our results underline the intriguing possibility of seasonal morphological changes related to mating, and more broadly that sex differences are influenced by sexual selection pressures mediated by temporal variation in mate competition.
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Coyne, D. P., J. R. Steadman, D. T. Lindgren, David Nuland, Durward Smith, J. R. Stavely, J. Reiser, and L. Sutton. "Breeding Great Northern and Pinto Dry Beans with Multiple Disease Resistance Combined with Improved Seed Quality, Adaptation, Yield, and Plant Type." HortScience 32, no. 3 (June 1997): 452B—452. http://dx.doi.org/10.21273/hortsci.32.3.452b.
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Common bacterial blight (CBB), rust (RU), and white mold (WM) are serious diseases of great northern (GN) and pinto (P) beans in Nebraska and Colorado. The bacterial diseases halo blight (HB) and brown spot (BS) are sporadic. Severe Fe-induced leaf chlorosis (Fe ILC) occurs on calcareous sites. Separate inoculated disease nurseries are used to screen for resistance to the pathogens causing the above diseases. Yields and seed quality of lines are also determined in non-disease trials. Sources of exotic resistance to the above pathogens and to Fe ILD have been identified and their inheritance determined. A non-structured recurrent selection scheme has mainly been used, occasionally with a backcross program, to combine high levels of the desired traits. Selection for highly heritable traits such as seed size, shape and color, maturity, plant architecture, and RU resistance occurs in early generations while traits of low heritability, such as CBB resistance, WM avoidance, yield, seed coat cracking resistance, and canning quality, are evaluated in separate replicated tests over several years and finally for yield in on-farm-trials. A number of multiple disease resistant, high-yielding, well-adapted GN and P lines are or will be released; P `Chase' (on about 30,000 acres in 1996) and GN WM 3-94-9 (for possible release).
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Miller, Sara E., Andrew W. Legan, Michael T. Henshaw, Katherine L. Ostevik, Kieran Samuk, Floria M. K. Uy, and Michael J. Sheehan. "Evolutionary dynamics of recent selection on cognitive abilities." Proceedings of the National Academy of Sciences 117, no. 6 (January 24, 2020): 3045–52. http://dx.doi.org/10.1073/pnas.1918592117.
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Cognitive abilities can vary dramatically among species. The relative importance of social and ecological challenges in shaping cognitive evolution has been the subject of a long-running and recently renewed debate, but little work has sought to understand the selective dynamics underlying the evolution of cognitive abilities. Here, we investigate recent selection related to cognition in the paper wasp Polistes fuscatus—a wasp that has uniquely evolved visual individual recognition abilities. We generate high quality de novo genome assemblies and population genomic resources for multiple species of paper wasps and use a population genomic framework to interrogate the probable mode and tempo of cognitive evolution. Recent, strong, hard selective sweeps in P. fuscatus contain loci annotated with functions in long-term memory formation, mushroom body development, and visual processing, traits which have recently evolved in association with individual recognition. The homologous pathways are not under selection in closely related wasps that lack individual recognition. Indeed, the prevalence of candidate cognition loci within the strongest selective sweeps suggests that the evolution of cognitive abilities has been among the strongest selection pressures in P. fuscatus’ recent evolutionary history. Detailed analyses of selective sweeps containing candidate cognition loci reveal multiple cases of hard selective sweeps within the last few thousand years on de novo mutations, mainly in noncoding regions. These data provide unprecedented insight into some of the processes by which cognition evolves.
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Wikelski, Martin. "Evolution of body size in Galapagos marine iguanas." Proceedings of the Royal Society B: Biological Sciences 272, no. 1576 (August 24, 2005): 1985–93. http://dx.doi.org/10.1098/rspb.2005.3205.
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Body size is one of the most important traits of organisms and allows predictions of an individual's morphology, physiology, behaviour and life history. However, explaining the evolution of complex traits such as body size is difficult because a plethora of other traits influence body size. Here I review what we know about the evolution of body size in a group of island reptiles and try to generalize about the mechanisms that shape body size. Galapagos marine iguanas occupy all 13 larger islands in this Pacific archipelago and have maximum island body weights between 900 and 12 000 g. The distribution of body sizes does not match mitochondrial clades, indicating that body size evolves independently of genetic relatedness. Marine iguanas lack intra- and inter-specific food competition and predators are not size-specific, discounting these factors as selective agents influencing body size. Instead I hypothesize that body size reflects the trade-offs between sexual and natural selection. We found that sexual selection continuously favours larger body sizes. Large males establish display territories and some gain over-proportional reproductive success in the iguanas' mating aggregations. Females select males based on size and activity and are thus responsible for the observed mating skew. However, large individuals are strongly selected against during El Niño-related famines when dietary algae disappear from the intertidal foraging areas. We showed that differences in algae sward (‘pasture’) heights and thermal constraints on large size are causally responsible for differences in maximum body size among populations. I hypothesize that body size in many animal species reflects a trade-off between foraging constraints and sexual selection and suggest that future research could focus on physiological and genetic mechanisms determining body size in wild animals. Furthermore, evolutionary stable body size distributions within populations should be analysed to better understand selection pressures on individual body size.
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Bravo, Washington, Ramon G. Leon, Jason A. Ferrell, Michael J. Mulvaney, and C. Wesley Wood. "Differentiation of Life-History Traits among Palmer Amaranth Populations (Amaranthus palmeri) and Its Relation to Cropping Systems and Glyphosate Sensitivity." Weed Science 65, no. 3 (May 2017): 339–49. http://dx.doi.org/10.1017/wsc.2017.14.
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Palmer amaranth’s ability to evolve resistance to different herbicides has been studied extensively, but there is little information about how this weed species might be evolving other life-history traits that could potentially make it more aggressive and difficult to control. We characterized growth and morphological variation among 10 Palmer amaranth populations collected in Florida and Georgia from fields with different cropping histories, ranging from continuous short-statured crops (vegetables and peanut) to tall crops (corn and cotton) and from intensive herbicide use history to organic production. Palmer amaranth populations differed in multiple traits such as fresh and dry weight, days to flowering, plant height, and leaf and canopy shape. Differences between populations for these traits ranged from 36% up to 87%. Although glyphosate-resistant (GR) populations collected from cropping systems including GR crops exhibited higher values of the aforementioned variables than glyphosate-susceptible (GS) populations, variation in traits was not explained by glyphosate resistance or distance between populations. Cropping system components such as crop rotation and crop canopy structure better explained the differences among populations. The higher growth of GR populations compared with GS populations was likely the result of multiple selection forces present in the cropping systems in which they grow rather than a pleiotropic effect of the glyphosate resistance trait. Results suggest that Palmer amaranth can evolve life-history traits increasing its growth and reproduction potential in cropping systems, which explains its rapid spread throughout the United States. Furthermore, our findings highlight the need to consider the evolutionary consequences of crop rotation structure and the use of more competitive crops, which might promote the selection of more aggressive biotypes in weed species with high genetic variability.
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Whalen, Matthew R., Krista J. Chang, Alexandria B. Jones, Gabriel Rivera, and Amy M. Worthington. "Fluctuating Asymmetry in the Polymorphic Sand Cricket (Gryllus firmus): Are More Functionally Important Structures Always More Symmetric?" Insects 13, no. 7 (July 16, 2022): 640. http://dx.doi.org/10.3390/insects13070640.
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Fluctuating asymmetry (FA) may serve as a reliable indicator of the functional importance of structures within an organism. Primary locomotor structures often display lower levels of FA than other paired structures, highlighting that selection can maintain symmetry in fitness-enhancing traits. Polyphenic species represent an attractive model for studying the fine-scale relationship between trait form and function, because multiple morphs exhibit unique life history adaptations that rely on different traits to maximize fitness. Here, we investigated whether individuals of the wing polyphenic sand field cricket (Gryllus firmus) maintain higher levels of symmetry in the bilateral structures most vital for maximizing fitness based on their specific life history strategy. We quantified FA and directional asymmetry (DA) across a suite of key morphological structures indicative of investment in somatic growth, reproduction, and flight capability for males and females across the flight-capable longwing (LW) and flight-incapable shortwing (SW) morphs. Although we did not find significant differences in FA across traits, hindwings lacked DA that was found in all other structures. We predicted that functionally important traits should maintain a higher level of symmetry; however, locomotor compensation strategies may reduce the selective pressures on symmetry or developmental constraints may limit the optimization between trait form and function.
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Teng, W. L., M. N. Sui, W. Li, D. P. Wu, X. Zhao, H. Y. Li, Y. P. Han, and W. B. Li. "Identification of quantitative trait loci underlying seed shape in soybean across multiple environments." Journal of Agricultural Science 156, no. 1 (December 12, 2017): 3–12. http://dx.doi.org/10.1017/s002185961700082x.
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AbstractSeed shape (SS) affects the yield and appearance of soybean seeds significantly. However, little detailed information has been reported about the quantitative trait loci (QTL) affecting SS, especially SS components such as seed length (SL), seed width (SW) and seed thickness (ST), and their mutual ratios of length-to-weight (SLW), length-to-thickness (SLT) and weight-to-thickness (SWT). The aim of the present study was to identify QTL underlying SS components using 129 recombinant inbred lines derived from a cross between Dongnong46 and L-100. Phenotypic data were collected from this population after it was grown across nine environments. A total of 213 simple sequence repeat markers were used to construct the genetic linkage map, which covered approximately 3623·39 cM, with an average distance of 17·01 cM between markers. Five QTL were identified as being associated with SL, five with SW, three with ST, four with SLW, two with SLT and three with SWT. These QTL could explain 1·46–22·16% of the phenotypic variation in SS component traits. Three QTL were identified in more than six tested environments three for SL, two for SW, one for ST, two for SLW and one for SLT. These QTL have great potential value for marker-assistant selection of SS in soybean seeds.
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Figueirido, Borja, Norman MacLeod, Jonathan Krieger, Miquel De Renzi, Juan Antonio Pérez-Claros, and Paul Palmqvist. "Constraint and adaptation in the evolution of carnivoran skull shape." Paleobiology 37, no. 3 (2011): 490–518. http://dx.doi.org/10.1666/09062.1.
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The evolutionary history of the Order Carnivora is marked by episodes of iterative evolution. Although this pattern is widely reported in different carnivoran families, the mechanisms driving the evolution of carnivoran skull morphology remain largely unexplored. In this study we use coordinate-point extended eigenshape analysis (CP-EES) to summarize aspects of skull shape in large fissiped carnivores. Results of these comparisons enable the evaluation of the role of different factors constraining the evolution of carnivoran skull design. Empirical morphospaces derived from mandible anatomy show that all hypercarnivores (i.e., those species with a diet that consists almost entirely of vertebrate flesh) share a set of traits involved in a functional compromise between bite force and gape angle, which is reflected in a strong pattern of morphological convergence. Although the paths followed by different taxa to reach this “hypercarnivore shape-space” differ because of phylogenetic constraints, the morphological signature of hypercarnivory in the mandible is remarkably narrow and well constrained. In contrast, CP-EES of cranial morphology does not reveal a similar pattern of shape convergence among hypercarnivores. This suggests a lesser degree of morphological plasticity in the cranium compared to the mandible, which probably results from a compromise between different functional demands in the cranium (e.g., feeding, vision, olfactory sense, and brain processing) whereas the mandible is only involved in food acquisition and processing. Combined analysis of theoretical and empirical morphospaces for these skull data also show the lower anatomical disparity of felids and hyaenids compared to canids and ursids. This indicates that increasing specialization within the hypercarnivorous niche may constrain subsequent morphological and ecological flexibility. During the Cenozoic, similar skull traits appeared in different carnivoran lineages, generated by similar selection pressures (e.g., toward hypercarnivory) and shared developmental pathways. These pathways were likely the proximate source of constraints on the degree of variation associated with carnivoran skull evolution and on its direction.
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Gumm, Jennifer M., and Tamra C. Mendelson. "The evolution of multi-component visual signals in darters (genus Etheostoma)." Current Zoology 57, no. 2 (April 1, 2011): 125–39. http://dx.doi.org/10.1093/czoolo/51.2.125.
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Abstract As complex traits evolve, each component of the trait may be under different selection pressures and could respond independently to distinct evolutionary forces. We used comparative methods to examine patterns of evolution in multiple components of a complex courtship signal in darters, specifically addressing the question of how nuptial coloration evolves across different areas of the body. Using spectral reflectance, we defined 4 broad color classes present on the body and fins of 17 species of freshwater fishes (genus Etheostoma) and quantified differences in hue within each color class. Ancestral state reconstruction suggests that most color traits were expressed in the most recent common ancestor of sampled species and that differences among species are mostly due to losses in coloration. The evolutionary lability of coloration varied across body regions; we found significant phylogenetic signal for orange color on the body but not for most colors on fins. Finally, patterns of color evolution and hue of the colors were correlated among the two dorsal fins and between the anterior dorsal and anal fins, but not between any of the fins and the body. The observed patterns support the hypothesis that different components of complex signals may be subject to distinct evolutionary pressures, and suggests that the combination of behavioral displays and morphology in communication may have a strong influence on patterns of signal evolution.
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Vieira, Jairo V., Giovani Olegario da Silva, and Leonardo S. Boiteux. "Genetic parameter and correlation estimates of processing traits in half-sib progenies of tropical-adapted carrot germplasm." Horticultura Brasileira 30, no. 1 (March 2012): 7–11. http://dx.doi.org/10.1590/s0102-05362012000100002.
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The estimate of the genetic parameters associated with processing (fresh-cut) traits, including root length (RL), is crucial for carrot breeding programs in tropical areas. The cultivar Alvorada is an important germplasm due to its resistance to nematodes, leaf blight, heat-tolerance, and high carotenoid content. Seventy-four 'Alvorada' half-sib progenies were evaluated during the summer of 2005 in the Federal District, Brazil, in a randomized complete block design with three replications. Thirteen competitive plants in each block were randomly selected and evaluated and/or classified for RL and for number of leaves (NL), leaf length (LL), root tip type (RT), root mass (RW), crown shape (CS), root diameter (RD), and xylem diameter (XD). The Pearson's correlation coefficients and the heritability values were estimated for all traits. The path analysis was also used considering the RL trait as dependent variable. The heritability for RL ranged from 12 to 44%. For the other traits, the values ranged from 3% (RD) to 79% (LL). Phenotypic and genotypic correlations among all traits were low to intermediate. Path analysis indicated positive direct relationship between RL and RW, whereas RD and XD displayed negative direct effect on RL. Longer roots had narrow diameter and narrow XD. Recurrent selection based upon either half-sib or S1 families would be more effective than mass phenotypic recurrent selection in increasing RL and to develop populations expressing multiple desirable processing traits in tropical-adapted carrot germplasm.
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Kaźmińska, Karolina, Ewelina Hallmann, Aleksandra Korzeniewska, Katarzyna Niemirowicz-Szczytt, and Grzegorz Bartoszewski. "Identification of Fruit-Associated QTLs in Winter Squash (Cucurbita maxima Duchesne) Using Recombinant Inbred Lines." Genes 11, no. 4 (April 14, 2020): 419. http://dx.doi.org/10.3390/genes11040419.
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Cucurbita maxima Duchesne squash and pumpkins are cultivated world-wide. Cucurbita maxima fruits are produced for fresh market and are valuable for food processing. Therefore, fruit characteristics and yield are the traits of high economic importance for breeders. To date, the genetic basis of fruit-associated traits in C. maxima have been poorly understood. In the present study, we evaluated fruit-associated traits and conducted quantitative trait locus (QTL) analysis using recombinant inbred lines (RILs) derived from a cross of two inbred lines with different fruit morphotypes. Phenotypic data for nine fruit traits (earliness, weight, number per plant, yield per plant, length and diameter, shape index, flesh thickness, sucrose content and dry matter content) were collected for RILs in two open-field experiments. Pairwise analysis of the phenotypic data revealed correlations among the fruit and yield-associated traits. Using a previously developed genetic map, we identified 26 QTLs for eight traits. The QTLs were found in 10 locations on eight chromosomes of C. maxima. The QTLs were detected across experiments and explained up to 41.4% of the observed phenotypic variations. Major-effect QTLs for multiple fruit-associated traits were clustered on chromosome 4, suggesting that this genomic region has been under selection during diversification and/or domestication of C. maxima.
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Si, Weimin, William A. Berggren, and Marie-Pierre Aubry. "Mosaic evolution in the middle Miocene planktonic foraminifera Fohsella lineage." Paleobiology 44, no. 2 (February 27, 2018): 263–72. http://dx.doi.org/10.1017/pab.2017.23.
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AbstractRecent studies have shown that modes of evolution, namely directional trend, random walk, and stasis, vary across morphologic traits and over the geographic range of a taxon. If so, is it possible that our interpretation of evolutionary modes is actually driven by our selection of traits in a study? In an attempt to answer this question, we have restudied the middle Miocene planktonic foraminifera Fohsella lineage, an iconic example of gradual morphologic evolution. In contrast to previous studies that have focused on the gross morphology as embodied by the edge view of tests, we analyze here multiple phenotypic traits chosen because their biologic and ecologic significance is well understood in living populations. We find that traits in the lineage did not evolve in concert. The timing and geographic pattern of changes in shape, coiling direction, size, and ecology were different. The evolution of this lineage is a mosaic combination of different evolutionary modes for different traits. We suggest that overemphasis on the evolution of some single trait, such as the edge-view outline, from narrow geographic ranges has significantly underestimated the dynamic evolutionary history of this group.
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Ramírez-Mejía, Andrés F., J. Nicolás Urbina-Cardona, and Francisco Sánchez. "The interplay of spatial scale and landscape transformation modulates the abundance and intraspecific variation in the ecomorphological traits of a phyllostomid bat." Journal of Tropical Ecology 38, no. 1 (November 10, 2021): 31–38. http://dx.doi.org/10.1017/s026646742100047x.
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AbstractLand use intensification imposes selective pressures that systematically change the frequency of wild population phenotypes. Growing evidence is biased towards the comparison of populations from discrete categories of land uses, ignoring the role of landscape emerging properties on the phenotype selection of wild fauna. Across the largest urban–rural gradient of the Colombian Orinoquia, we measured ecomorphological traits of 216 individuals of the flat-faced fruit-eating bat Artibeus planirostris. We did this to evaluate the scale of effect at which landscape transformation better predicts changes in phenotype and abundance of an urban-tolerant species. Forest percentage at 1.25 km was the main predictor affecting negatively bat abundance and positively its wing aspect ratio and body mass. Landscape variables affected forearm length at all spatial scales, this effect appeared to be sex-dependent, and the most important predictor, forest percentage at 0.5 km, had a negative effect on this trait. Our results indicate that landscape elements and spatial scale interact to shape ecomorphological traits and the abundance of A. planirostris. Interestingly, the scale of effect coincided at 1.25 km among all biological responses, suggesting that species’ abundance can be linked to the variation on phenotype under different environmental filters across landscape scenarios.
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Ferjani, Raoudha, Ramona Marasco, Eleonora Rolli, Hanene Cherif, Ameur Cherif, Maher Gtari, Abdellatif Boudabous, Daniele Daffonchio, and Hadda-Imene Ouzari. "The Date Palm Tree Rhizosphere Is a Niche for Plant Growth Promoting Bacteria in the Oasis Ecosystem." BioMed Research International 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/153851.
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In arid ecosystems environmental factors such as geoclimatic conditions and agricultural practices are of major importance in shaping the diversity and functionality of plant-associated bacterial communities. Assessing the influence of such factors is a key to understand (i) the driving forces determining the shape of root-associated bacterial communities and (ii) the plant growth promoting (PGP) services they provide. Desert oasis environment was chosen as model ecosystem where agriculture is possible by the microclimate determined by the date palm cultivation. The bacterial communities in the soil fractions associated with the root system of date palms cultivated in seven oases in Tunisia were assessed by culture-independent and dependent approaches. According to 16S rRNA gene PCR-DGGE fingerprinting, the shapes of the date palm rhizosphere bacterial communities correlate with geoclimatic features along a north-south aridity transect. Despite the fact that the date palm root bacterial community structure was strongly influenced by macroecological factors, the potential rhizosphere services reflected in the PGP traits of isolates screenedin vitrowere conserved among the different oases. Such services were exerted by the 83% of the screened isolates. The comparable numbers and types of PGP traits indicate their importance in maintaining the plant functional homeostasis despite the different environmental selection pressures.