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1
Simpson, Richard K., David R. Wilson, Allison F. Mistakidis, Daniel J. Mennill, and Stéphanie M. Doucet. "Sympatry drives colour and song evolution in wood-warblers (Parulidae)." Proceedings of the Royal Society B: Biological Sciences 288, no. 1942 (January 13, 2021): 20202804. http://dx.doi.org/10.1098/rspb.2020.2804.
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Closely related species often exhibit similarities in appearance and behaviour, yet when related species exist in sympatry, signals may diverge to enhance species recognition. Prior comparative studies provided mixed support for this hypothesis, but the relationship between sympatry and signal divergence is likely nonlinear. Constraints on signal diversity may limit signal divergence, especially when large numbers of species are sympatric. We tested the effect of sympatric overlap on plumage colour and song divergence in wood-warblers (Parulidae), a speciose group with diverse visual and vocal signals. We also tested how number of sympatric species influences signal divergence. Allopatric species pairs had overall greater plumage and song divergence compared to sympatric species pairs. However, among sympatric species pairs, plumage divergence positively related to the degree of sympatric overlap in males and females, while male song bandwidth and syllable rate divergence negatively related to sympatric overlap. In addition, as the number of species in sympatry increased, average signal divergence among sympatric species decreased, which is likely due to constraints on warbler perceptual space and signal diversity. Our findings reveal that sympatry influences signal evolution in warblers, though not always as predicted, and that number of sympatric species can limit sympatry's influence on signal evolution.
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Henderson, M. A., and T. G. Northcote. "Retinal Structure of Sympatric and Allopatric Populations of Cutthroat Trout (Salmo clarki clarki) and Dolly Varden Char (Salvelinus malma) in Relation to their Spatial Distribution." Canadian Journal of Fisheries and Aquatic Sciences 45, no. 7 (July 1, 1988): 1321–26. http://dx.doi.org/10.1139/f88-155.
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Retinal structures of cutthroat trout (Salmo clarki clarki) and Dolly Varden char (Salvelinus malma) were compared to determine if these features were consistent with the different light regimes in which the species live, depending on their sympatry or allopatry in lakes. Cone cell density in sympatric trout was over twice that of sympatric char and rod cell density was slightly less. The cross-sectional size of cone cells in sympatric trout was approximately 30% less than in sympatric char. The ratios of photoreceptor cells to ganglion cells in sympatric trout and char retinas were approximately 40:1 and 80:1, respectively. There were no differences between sympatric and allopatric trout with respect to these structural features. Estimates of cone cell density, cone size, and number of photoreceptor cells per ganglion cell for allopatric char were significantly different and intermediate between those for sympatric trout and char. All four populations had similar cone cell mosaics with four paired cones surrounding each single cone. Results are considered in relation to differences in vertical distribution and feeding of sympatric and allopatric populations in three study lakes.
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Feller, Anna F., Marcel P. Haesler, Catherine L. Peichel, and Ole Seehausen. "Genetic architecture of a key reproductive isolation trait differs between sympatric and non-sympatric sister species of Lake Victoria cichlids." Proceedings of the Royal Society B: Biological Sciences 287, no. 1924 (April 8, 2020): 20200270. http://dx.doi.org/10.1098/rspb.2020.0270.
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One hallmark of the East African cichlid radiations is the rapid evolution of reproductive isolation that is robust to full sympatry of many closely related species. Theory predicts that species persistence and speciation in sympatry with gene flow are facilitated if loci of large effect or physical linkage (or pleiotropy) underlie traits involved in reproductive isolation. Here, we investigate the genetic architecture of a key trait involved in behavioural isolation, male nuptial coloration, by crossing two sister species pairs of Lake Victoria cichlids of the genus Pundamilia and mapping nuptial coloration in the F2 hybrids. One is a young sympatric species pair, representative of an axis of colour motif differentiation, red-dorsum versus blue, that is highly recurrent in closely related sympatric species. The other is a species pair representative of colour motifs, red-chest versus blue, that are common in allopatric but uncommon in sympatric closely related species. We find significant quantitative trait loci (QTLs) with moderate to large effects (some overlapping) for red and yellow in the sympatric red-dorsum × blue cross, whereas we find no significant QTLs in the non-sympatric red-chest × blue cross. These findings are consistent with theory predicting that large effect loci or linkage/pleiotropy underlying mating trait differentiation could facilitate speciation and species persistence with gene flow in sympatry.
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McCoy, Karen D. "Sympatric speciation in parasites – what is sympatry?" Trends in Parasitology 19, no. 9 (September 2003): 400–404. http://dx.doi.org/10.1016/s1471-4922(03)00194-6.
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Rice, Amber M., Aaron R. Leichty, and David W. Pfennig. "Parallel evolution and ecological selection: replicated character displacement in spadefoot toads." Proceedings of the Royal Society B: Biological Sciences 276, no. 1676 (September 2, 2009): 4189–96. http://dx.doi.org/10.1098/rspb.2009.1337.
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Ecological character displacement—trait evolution stemming from selection to lessen resource competition between species—is most often inferred from a pattern in which species differ in resource-use traits in sympatry but not in allopatry, and in which sympatric populations within each species differ from conspecific allopatric populations. Yet, without information on population history, the presence of a divergent phenotype in multiple sympatric populations does not necessarily imply that there has been repeated evolution of character displacement. Instead, such a pattern may arise if there has been character displacement in a single ancestral population, followed by gene flow carrying the divergent phenotype into multiple, derived, sympatric populations. Here, we evaluate the likelihood of such historical events versus ongoing ecological selection in generating divergence in trophic morphology between multiple populations of spadefoot toad ( Spea multiplicata ) tadpoles that are in sympatry with a heterospecific and those that are in allopatry. We present both phylogenetic and population genetic evidence indicating that the same divergent trait, which minimizes resource competition with the heterospecific, has arisen independently in multiple sympatric populations. These data, therefore, provide strong indirect support for competition's role in divergent trait evolution.
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Kerschbaumer, Michaela, Lisbeth Postl, and Christian Sturmbauer. "Microevolutionary change in viscerocranial bones under congeneric sympatry in the Lake Tanganyikan cichlid genus Tropheus." Hydrobiologia 848, no. 16 (February 22, 2021): 3639–53. http://dx.doi.org/10.1007/s10750-021-04536-7.
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AbstractThe endemic Lake Tanganyika cichlid genus Tropheus lives at rocky shores all around the lake and comprises six species which are subdivided into about 120 morphologically similar but color-wise distinct populations. Typically, they live without a second Tropheus species, but there are some regions where two or even three sister species live in sympatry. We previously showed that there are morphological differences concerning head shape, eye size and insertion of fins among populations living alone compared to those living in sympatry with a second Tropheus. This study goes one step further to test if sympatry affects the shape of viscerocranial bones. By means of geometric morphometrics, we compare the shape of four bones among thirteen Tropheus populations, some of which in sympatry and some living alone. We quantify patterns of shape variation and estimate morphological disparity among the four bony elements in the study species and populations. We found consistent differences in the shape of one bony element among non-sympatric and sympatric populations, besides an extensive variation in the shape of viscerocranial bones within and among species. Furthermore, sexual dimorphism in Tropheus is clearly evident in the viscerocranial bones analyzed. We suggest that the relatively subtle morphological signal in sympatric vs. non-sympatric Tropheus populations is owed to the fact that the depth segregation does not yet represent a full shift in the trophic niche, albeit our data confirm that differences in ecologically relevant traits, such as bones of the preorbital region, play an important role in the process of niche separation and in the context of explosive diversification of cichlid fishes.
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Bodaly, R. A., J. W. Clayton, C. C. Lindsey, and J. Vuorinen. "Evolution of Lake Whitefish (Coregonus clupeaformis) in North America during the Pleistocene: Genetic Differentiation between Sympatric Populations." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 4 (April 1, 1992): 769–79. http://dx.doi.org/10.1139/f92-086.
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We use electrophoretic data on dehydrogenase enzymes to examine the relatedness of sympatric populations of lake whitefish (Coregonus clupeaformis) and provide evidence for the existence of a glacial refuge race of lake whitefish in eastern North America. This Acadian race is presently found in New England, the Gaspé peninsula of Québec, and New Brunswick. It probably survived glaciation in a refugium on the exposed coastal plain of northeastern North America. In areas of contact, most glacial races appear to introgress and do not coexist in sympatry. However, sympatric pairs of populations occur (or occurred) within the ranges of all races of lake whitefish. Allele frequencies for at least one enzyme system examined for most sympatric pairs were significantly different, indicating that these sympatric populations are wholly or substantially, isolated reproductively from each other. Both members of the population pairs examined in the Yukon Territory, Ontario, and Labrador were genetically characteristic of the glacial races of their region. This suggests that they are not the result of speciation due to geographic isolation in different glacial refugia. Thus, their origin appears to be postglacial, but may be older if present genetic similarities are due to recent gene flow between sympatric forms.
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Hume, Jeremy M. B., and Thomas G. Northcote. "Initial Changes in Use of Space and Food by Experimentally Segregated Populations of Dolly Varden (Salvelinus malma) and Cutthroat Trout (Salmo clarki)." Canadian Journal of Fisheries and Aquatic Sciences 42, no. 1 (January 1, 1985): 101–9. http://dx.doi.org/10.1139/f85-013.
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Dolly Varden (Salvelinus malma) (N = 881) and cutthroat trout (Salmo clarki) (N = 1571) were captured from a native lacustrine sympatric stock and transferred to two nearby lakes, formerly fishless, to establish allopatric populations with genetic backgrounds similar to the donor stock. Nearshore (5- and 10-m depth contours) vertical distributions of segregated Dolly Varden and cutthroat trout, between spring and autumn of the first 18 mo after transfer, did not differ significantly from those in their sympatric lake. Dolly Varden were captured mainly near the bottom while cutthroat trout were more evenly distributed throughout the water column. Nevertheless, initially the allopatric Dolly Varden rapidly became highly planktivorous, virtually eliminating midwater populations of Chaoborus trivittatus and C. americanus (third and fourth instar larvae) within a year. They later ate mainly benthic organisms as in the sympatric lake. Although allopatric cutthroat trout had a similar effect on Chaoborus larvae in their lake, they also ate more large benthic prey than did those in sympatry with Dolly Varden in the donor lake. These results suggest that while there may be genetic control restricting broad vertical use of space by formerly sympatric Dolly Varden shortly after being placed in allopatry, such control is flexible enough that a highly benthofagous stock in sympatry quickly becomes planktivorous in the absence of cutthroat trout.
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Huang, Yan, Xiaoyi Wang, Xin Yang, Jianping Jiang, and Junhua Hu. "Unveiling the roles of interspecific competition and local adaptation in phenotypic differentiation of parapatric frogs." Current Zoology 66, no. 4 (January 24, 2020): 383–92. http://dx.doi.org/10.1093/cz/zoaa001.
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Abstract Understanding how ecological processes affect phenotypic evolution has been and continues to be an important goal of ecology and evolutionary biology. Interspecific competition for resources can be a selective force driving phenotypic differentiation that reduces competition among sympatric species (character divergence), enabling closely-related species to coexist. However, although patterns of character divergence are well documented in both empirical and theoretical researches, how local adaptation to abiotic environment affects trait evolution in the face of interspecific competition is less known. Here, we investigate how patterns in morphological traits of 2 parapatric frog species, Feirana quadranus and F. taihangnica, vary among allopatric and sympatric regions using range-wide data derived from extensive field surveys. Feirana quadranus was overall larger than F. taihangnica in body size (i.e., snout–vent length [SVL]), and the difference between SVL of both species in sympatry was larger than that in allopatry. From allopatry to sympatry, the 2 species diverged in foot and hand traits, but converged in eye size and interorbital span, even when we controlled for the effects of geographic gradients. Sympatric divergence in SVL, hand and foot traits is likely acting as a case of evolutionary shift caused by interspecific competition. In contrast, sympatric convergence of eye-related traits may derive at least partly from adaptation to local environments. These results imply the relative roles of interspecific competition and local adaptation in shaping phenotypic diversification. Our findings illustrate how traits evolve in parapatric species pair due to sympatric divergent and convergent evolution. It thus provides insights into understanding underlying evolutionary processes of parapatric species, that is, competition and local adaptation.
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Bearzi, Maddalena, and Craig B. Stanford. "Dolphins and African apes: comparisons of sympatric socio-ecology." Contributions to Zoology 76, no. 4 (2007): 235–54. http://dx.doi.org/10.1163/18759866-07604003.
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Dolphins and African apes are distantly related mammalian taxa that exhibit striking convergences in their socioecology. In both cetaceans and African apes, two or more closely related species sometimes occur in sympatry. However, detailed reviews of the ways in which sympatric associations of dolphins and apes are similar have not been done. As field studies of dolphins and apes have accumulated, comparisons of how the two groups avoid direct food competition when in sympatry have become possible. In this paper we review sympatric ecology among dolphins and African apes, and examine convergences in species-associations in each taxa. We review evidence for hypotheses that seek to explain avoidance of food competition, and consider whether ape-dolphin similarities in this area may be related to the way in which social groups in both taxa optimally exploit their food resources.
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Pfennig, Karin S., and Alyssa B. Stewart. "Asymmetric reproductive character displacement in male aggregation behaviour." Proceedings of the Royal Society B: Biological Sciences 278, no. 1716 (December 22, 2010): 2348–54. http://dx.doi.org/10.1098/rspb.2010.2196.
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Reproductive character displacement—the evolution of traits that minimize reproductive interactions between species—can promote striking divergence in male signals or female mate preferences between populations that do and do not occur with heterospecifics. However, reproductive character displacement can affect other aspects of mating behaviour. Indeed, avoidance of heterospecific interactions might contribute to spatial (or temporal) aggregation of conspecifics. We examined this possibility in two species of hybridizing spadefoot toad (genus Spea ). We found that in Spea bombifrons sympatric males were more likely than allopatric males to associate with calling males. Moreover, contrary to allopatric males, sympatric S. bombifrons males preferentially associated with conspecific male calls. By contrast, Spea multiplicata showed no differences between sympatry and allopatry in likelihood to associate with calling males. Further, sympatric and allopatric males did not differ in preference for conspecifics. However, allopatric S. multiplicata were more variable than sympatric males in their responses. Thus, in S. multiplicata , character displacement may have refined pre-existing aggregation behaviour. Our results suggest that heterospecific interactions can foster aggregative behaviour that might ultimately contribute to clustering of conspecifics. Such clustering can generate spatial or temporal segregation of reproductive activities among species and ultimately promote reproductive isolation.
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CARSON, HAMPTON L. "Sympatric pest." Nature 338, no. 6213 (March 1989): 304. http://dx.doi.org/10.1038/338304a0.
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Verma, Krishna Kumar. "Sympatric speciation." Journal of Threatened Taxa 2, no. 4 (April 26, 2010): 820–23. http://dx.doi.org/10.11609/jott.o2367.820-3.
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Coyne, Jerry A. "Sympatric speciation." Current Biology 17, no. 18 (September 2007): R787—R788. http://dx.doi.org/10.1016/j.cub.2007.06.056.
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Das, Mrinal K., and Joseph S. Nelson. "Hybridization between northern redbelly dace (Phoxinus eos) and finescale dace (Phoxinus neogaeus) (Osteichthyes: Cyprinidae) in Alberta." Canadian Journal of Zoology 67, no. 3 (March 1, 1989): 579–84. http://dx.doi.org/10.1139/z89-083.
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Hybridization between northern redbelly dace (Phoxinus eos) and finescale dace (Phoxinus neogaeus) was studied in Upper Pierre Grey Lake, Alberta. Sympatric parental and hybrid populations were compared with allopatric populations from Cameron Lake and Tay Lake, Alberta. Canonical variates and principal components analyses, using 31 morphological characters, revealed that the two parental groups were bridged by an intermediate all-female hybrid group in Upper Pierre Grey Lake. Hybrids made up approximately 33% of the individuals of the sympatic population. Neither backcross nor hybrid F2 individuals could be identified from the analyses, although the majority of hybrids were morphologically more similar to P. neogaeus than to P. eos. No clear evidence of introgressive hybridization was found in either of the sympatric parental species.
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Näslund, Ingemar, Erik Degerman, and Fredrik Nordwall. "Brown trout (Salmo trutta) habitat use and life history in Swedish streams: possible effects of biotic interactions." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 4 (April 1, 1998): 1034–42. http://dx.doi.org/10.1139/f97-313.
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To test if habitat use and life history of stream-dwelling brown trout (Salmo trutta) differed between allopatric and sympatric situations, we compared three streams with differing fish communities and used data from a large national database containing electrofishing results from Swedish streams. In the three-creek study, allopatric brown trout used all habitats and shifted from nursery areas in riffles to pool habitats, where adult growth and survival were higher. Mainly females shifted habitat and this was undertaken after age 1. Sympatric brown trout under intense pressure from other fish species remained in the riffles throughout their life cycle. Under moderate pressure from other species, larger brown trout used slow-flowing habitats. Early growth was more rapid in sympatry. Sympatric brown trout also had a lower adult to juvenile growth ratio and lower adult survival and matured earlier than allopatric brown trout. The data from the nationwide database showed that frequency of occurrence and abundance of brown trout were negatively associated with the number of coexisting fish species. It was also verified that the habitat shifts between riffles and pools were more common and possibly more beneficial in terms of growth and survival in allopatry. In addition the existence of differences in juvenile growth between allopatric and sympatric populations was verified.
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Pigeon, Dany, Julian J. Dodson, and Louis Bernatchez. "A mtDNA analysis of spatiotemporal distribution of two sympatric larval populations of rainbow smelt (Osmerus mordax) in the St. Lawrence River estuary, Quebec, Canada." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 7 (July 1, 1998): 1739–47. http://dx.doi.org/10.1139/f98-057.
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Ecological isolation through resource partitioning is invoked as a major factor for explaining the persistence of genetically distinct yet closely related sympatric populations. Two genetically distinct sympatric populations of anadromous rainbow smelt (Osmerus mordax) exist in the middle estuary of the St. Lawrence River. The persistence of these coexisting populations in sympatry is in conflict with current theoretical concepts predicting population richness. In the present study, we performed mtDNA PCR-RFLP analysis of 922 larvae from 33 sampling stations to test the hypothesis that the larvae belonging to the two sympatric smelt populations of the St. Lawrence middle estuary are spatially segregated and that such segregation may promote the persistence of the populations. Results clearly revealed spatial homogeneity in the relative distribution of larvae from the two populations. Consequently, they did not support our working hypothesis that larvae belonging to the two sympatric smelt populations are spatially segregated. Two alternative explanations may account for the lack of spatial partitioning observed here. Competition may not be important enough to promote resource partitioning at the larval stage. Alternatively, resource partitioning occurs, but not spatially. This study also demonstrated that the effect of historical events may have been as important as contemporary ecological settings in determining genetic population structure in smelt.
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Christie, Kyle, Jonathan P. Doan, Wendy C. Mcbride, and Sharon Y. Strauss. "Asymmetrical reproductive barriers in sympatric jewelflowers: are floral isolation, genetic incompatibilities and floral trait displacement connected?" Biological Journal of the Linnean Society 133, no. 3 (March 27, 2021): 835–52. http://dx.doi.org/10.1093/biolinnean/blab027.
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Abstract Floral visitors influence reproductive interactions among sympatric plant species, either by facilitating assortative mating and contributing to reproductive isolation, or by promoting heterospecific pollen transfer, potentially leading to reproductive interference or hybridization. We assessed preference and constancy of floral visitors on two co-occurring jewelflowers [Streptanthus breweri and Streptanthus hesperidis (Brassicaceae)] using field arrays, and quantified two floral rewards potentially important to foraging choice – pollen production and nectar sugar concentration – in a greenhouse common garden. Floral visitors made an abundance of conspecific transitions between S. breweri individuals, which thus experienced minimal opportunities for heterospecific pollen transfer from S. hesperidis. In contrast, behavioural isolation for S. hesperidis was essentially absent due to pollinator inconstancy. This pattern emerged across multiple biotic environments and was unrelated to local density dependence. S. breweri populations that were sympatric with S. hesperidis had higher nectar sugar concentrations than their sympatric congeners, as well as allopatric conspecifics. Previous work shows that S. breweri suffers a greater cost to hybridization than S. hesperidis, and here we find that it also shows asymmetrical floral isolation and floral trait displacement in sympatry. These findings suggest that trait divergence may reduce negative reproductive interactions between sympatric but genetically incompatible relatives.
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Naretto, Sergio, Cecilia S. Blengini, Gabriela Cardozo, and Margarita Chiaraviglio. "Pre- and Postcopulatory Traits ofSalvatorMale Lizards in Allopatry and Sympatry." Scientifica 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/8176267.
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The reproductive traits of males are under influence of sexual pressures before and after copulation. The strength of sexual selection varies across populations because they undergo varying competition for mating opportunities. Besides intraspecific pressures, individuals seem to be subjected to pressures driven by interspecific interactions in sympatry. Lizards may vary their reproductive strategies through varying sexual characters, body size, gonadal investment, and sperm traits. We evaluated the reproductive traits, involved in pre- and postcopulatory competition, in allopatric and sympatric populations ofSalvatorlizards. We observed a spatial gradient of male competition among populations, with the following order: allopatric zone ofS. rufescens; sympatric zone; and allopatric zone ofS. merianae. Accordingly, variation in secondary sexual character, the relative testis mass, and the length of sperm component was observed between allopatry and sympatry in each species, suggesting differences in the investment of reproductive traits. However, we found that these twoSalvatorspecies did not differ in secondary sexual characters in sympatry. Interestingly, the trade-off between testes and muscle varied differently from allopatry to sympatry between theseSalvatorspecies, suggesting that the influence of social context on reproductive traits investment would affect lizard species differently.
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Fu, Haibo, Liangzhi Zhang, Chao Fan, Wenjing Li, Chuanfa Liu, He Zhang, Qi Cheng, and Yanming Zhang. "Sympatric Yaks and Plateau Pikas Promote Microbial Diversity and Similarity by the Mutual Utilization of Gut Microbiota." Microorganisms 9, no. 9 (September 6, 2021): 1890. http://dx.doi.org/10.3390/microorganisms9091890.
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Interactions between species provide the basis for understanding coexisting mechanisms. The plateau pika (Ochotona curzoniae) and the yak (Bos grunniens) are considered competitors because they have shared habitats and consumed similar food on the Qinghai–Tibetan Plateau for more than 1 million years. Interestingly, the population density of plateau pikas increases with yak population expansion and subsequent overgrazing. To reveal the underlying mechanism, we sequenced the fecal microbial 16S rDNA from both sympatric and allopatric pikas and yaks. Our results indicated that sympatry increased both gut microbial diversity and similarity between pikas and yaks. The abundance of Firmicutes, Proteobacteria, Cyanobacteria, and Tenericutes decreased, while that of Verrucomicrobia increased in sympatric pikas. As for sympatric yaks, Firmicutes, Bacteroidetes, and Spirochaetes significantly increased, while Cyanobacteria, Euryarchaeota, and Verrucomicrobia significantly decreased. In sympatry, plateau pikas acquired 2692 OTUs from yaks, and yaks obtained 453 OTUs from pikas. The predominant horizontally transmitted bacteria were Firmicutes, Bacteroidetes, Verrucomicrobia, and Proteobacteria. These bacteria enhanced the enrichment of pathways related to prebiotics and immunity for pikas, such as heparin sulfate, heparin, chitin disaccharide, chondroitin-sulfate-ABC, and chondroitin-AC degradation pathways. In yaks, the horizontally transmitted bacteria enhanced pathways related to hepatoprotection, xenobiotic biodegradation, and detoxification. Our results suggest that horizontal transmission is a process of selection, and pikas and yaks tend to develop reciprocity through the horizontal transmission of gut microbiota.
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Cucherousset, Julien, Libor Závorka, Sergine Ponsard, Régis Céréghino, and Frédéric Santoul. "Stable isotope niche convergence in coexisting native and non-native salmonids across age classes." Canadian Journal of Fisheries and Aquatic Sciences 77, no. 8 (August 2020): 1359–65. http://dx.doi.org/10.1139/cjfas-2019-0186.
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Niche divergence resulting from coevolution is commonly believed to favour coexistence among competing species; however, recent investigations have demonstrated that an unexpected niche convergence can occur when native and non-native species coexist. Yet, our understanding of the ontogenetic characteristics of this niche convergence remains limited. In the present study, we quantified the stable isotope niche of native brown trout (Salmo trutta) in allopatry and sympatry with non-native brook trout (Salvelinus fontinalis) across four age classes. Our results demonstrated that brown trout displayed a stable isotope niche closer to brook trout in sympatry than in allopatry, which was likely driven by an increased consumption of terrestrial invertebrates by sympatric brown trout. Stable isotope niche overlap was the strongest for young-of-the-year individuals and the intensity of overlap between sympatric native brown trout and non-native brook trout decreased during ontogeny. These findings indicate that niche convergence between the species occur at the earliest age class of the native species and are maintained across ontogeny.
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Li, Kexin, Shangzhe Zhang, Xiaoying Song, Alexandra Weyrich, Yinjia Wang, Xi Liu, Na Wan, et al. "Genome evolution of blind subterranean mole rats: Adaptive peripatric versus sympatric speciation." Proceedings of the National Academy of Sciences 117, no. 51 (December 4, 2020): 32499–508. http://dx.doi.org/10.1073/pnas.2018123117.
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Speciation mechanisms remain controversial. Two speciation models occur in Israeli subterranean mole rats, genusSpalax: a regional speciation cline southward of four peripatric climatic chromosomal species and a local, geologic-edaphic, genic, and sympatric speciation. Here we highlight their genome evolution. The five species were separated into five genetic clusters by single nucleotide polymorphisms, copy number variations (CNVs), repeatome, and methylome in sympatry. The regional interspecific divergence correspond to Pleistocene climatic cycles. Climate warmings caused chromosomal speciation. Triple effective population size,Ne, declines match glacial cold cycles. Adaptive genes evolved under positive selection to underground stresses and to divergent climates, involving interspecies reproductive isolation. Genomic islands evolved mainly due to adaptive evolution involving ancient polymorphisms. Repeatome, including both CNV and LINE1 repetitive elements, separated the five species. Methylation in sympatry identified geologically chalk-basalt species that differentially affect thermoregulation, hypoxia, DNA repair, P53, and other pathways. Genome adaptive evolution highlights climatic and geologic-edaphic stress evolution and the two speciation models, peripatric and sympatric.
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Krauss, SL. "Variation in Leptospermum trinervium (Myrtaceae): a problem species and the species problem." Australian Systematic Botany 7, no. 3 (1994): 251. http://dx.doi.org/10.1071/sb9940251.
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Leptospermum trinervium is a variable species that has proved to be taxonomically puzzling because of interpopulation heterogeneity and sympatry of extreme forms. Variation within the species was initially investigated by phenetic analysis of adult morphology from herbarium specimens. Clustering analysis first suggested the existence of two major phenetic groups. Group definition was refined using discriminant function analysis by defining the most phenetically distinct groups. Ordination procedures (canonical variate analysis and non-metric multidimensional scaling) confirmed the absolute distinctness of these two phenetic groups. Seven locations were then studied in detail. Three of these locations contained sympatric populations of the two phenetic forms. Phenetic analysis of adult morphology using discriminant function analysis and univariate analyses supported the recognition of the two phenetic groups but also indicated a high degree of distinctness among all populations, and particularly between sympatric populations where no intermediates were found. Diagnostic differences were retained even when seeds from these populations were cultivated under standardised conditions, indicating a genetic basis to the morphological heterogeneity. Preliminary data on genetic structure from allozymes indicated that the sympatric populations were less similar to each other than they were to other phenetically similar populations elsewhere, suggesting a barrier to gene flow between these sympatric populations. These results suggest that the two phenetic groups should be recognised as distinct, but variable, species.
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Gkenas, Christos, Maria Filomena Magalhães, Julien Cucherousset, Rafael Leonardo Orjuela, and Filipe Ribeiro. "Dietary niche divergence between two invasive fish in Mediterranean streams." Knowledge & Management of Aquatic Ecosystems, no. 420 (2019): 24. http://dx.doi.org/10.1051/kmae/2019018.
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Clarifying the mechanisms associated with the coexistence of invasive species is important to understand the overall impact of multiple invasions on recipient communities. Here we examined whether divergence or convergence in dietary niche occurred when invasive Lepomis gibbosus and Australoheros facetus coexist in Iberian streams. We used stomach content analyses to determine dietary niche composition, width, and overlap in allopatric and sympatric counterparts in the Lower Guadiana throughout the dry-season. The variations in dietary niche between pumpkinseed and the cichlid were consistent with predictions derived from the niche divergence hypothesis. Although there were no changes in the use of plant material from allopatry to sympatry in either species, sympatric pumpkinseed and the cichlid displayed marked shifts in the use of animal prey and a decrease in niche width relative to allopatric counterparts. Moreover, sympatric pumpkinseed and cichlid showed similar niche width but differed significantly in plant and animal prey use. Taken together these results suggest that divergence in dietary niches may play a role in mediating coexistence of multiple invaders in Iberian streams.
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Muñoz-Ramírez, Carlos P., Pierre-Paul Bitton, Stéphanie M. Doucet, and Lacey L. Knowles. "Mimics here and there, but not everywhere: Müllerian mimicry in Ceroglossus ground beetles?" Biology Letters 12, no. 9 (September 2016): 20160429. http://dx.doi.org/10.1098/rsbl.2016.0429.
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The ground beetle genus Ceroglossus contains co-distributed species that show pronounced intraspecific diversity in the form of geographical colour morphs. While colour morphs among different species appear to match in some geographical regions, in others, there is little apparent colour matching. Mimicry is a potential explanation for covariation in colour patterns, but it is not clear whether the degree of sympatric colour matching is higher than expected by chance given the obvious mismatches among morphs in some regions. Here, we used reflectance spectrometry to quantify elytral coloration from the perspective of an avian predator to test whether colour similarity between species is, indeed, higher in sympatry. After finding no significant phylogenetic signal in the colour data, analyses showed strong statistical support for sympatric colour similarity between species despite the apparent lack of colour matching in some areas. We hypothesize Müllerian mimicry as the responsible mechanism for sympatric colour similarity in Ceroglossus and discuss potential explanations and future directions to elucidate why mimicry has not developed similar levels of interspecific colour resemblance across space.
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Giraud, Tatiana, Lorys M. M. A. Villaréal, Frédéric Austerlitz, Mickaël Le Gac, and Claire Lavigne. "Importance of the Life Cycle in Sympatric Host Race Formation and Speciation of Pathogens." Phytopathology® 96, no. 3 (March 2006): 280–87. http://dx.doi.org/10.1094/phyto-96-0280.
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Numerous morphological species of pathogenic fungi have been shown to actually encompass several genetically isolated lineages, often specialized on different hosts and, thus, constituting host races or sibling species. In this article, we explore theoretically the importance of some aspects of the life cycle on the conditions of sympatric divergence of host races, particularly in fungal plant pathogens. Because the life cycles classically modeled by theoreticians of sympatric speciation correspond to those of free-living animals, sympatric divergence of host races requires the evolution of active assortative mating or of active host preference if mating takes place on the hosts. With some particular life cycles with restricted dispersal between selection on the host and mating, we show that divergence can occur in sympatry and lead to host race formation, or even speciation, by a mere process of specialization, with strong divergent adaptive selection. Neither active assortative mating nor active habitat choice is required in these cases, and this may explain why the phylo-genetic species concept seems more appropriate than the biological species concept in these organisms.
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Stankowski, Sean, Anja M. Westram, Zuzanna B. Zagrodzka, Isobel Eyres, Thomas Broquet, Kerstin Johannesson, and Roger K. Butlin. "The evolution of strong reproductive isolation between sympatric intertidal snails." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1806 (July 13, 2020): 20190545. http://dx.doi.org/10.1098/rstb.2019.0545.
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The evolution of strong reproductive isolation (RI) is fundamental to the origins and maintenance of biological diversity, especially in situations where geographical distributions of taxa broadly overlap. But what is the history behind strong barriers currently acting in sympatry? Using whole-genome sequencing and single nucleotide polymorphism genotyping, we inferred (i) the evolutionary relationships, (ii) the strength of RI, and (iii) the demographic history of divergence between two broadly sympatric taxa of intertidal snail. Despite being cryptic, based on external morphology, Littorina arcana and Littorina saxatilis differ in their mode of female reproduction (egg-laying versus brooding), which may generate a strong post-zygotic barrier. We show that egg-laying and brooding snails are closely related, but genetically distinct. Genotyping of 3092 snails from three locations failed to recover any recent hybrid or backcrossed individuals, confirming that RI is strong. There was, however, evidence for a very low level of asymmetrical introgression, suggesting that isolation remains incomplete. The presence of strong, asymmetrical RI was further supported by demographic analysis of these populations. Although the taxa are currently broadly sympatric, demographic modelling suggests that they initially diverged during a short period of geographical separation involving very low gene flow. Our study suggests that some geographical separation may kick-start the evolution of strong RI, facilitating subsequent coexistence of taxa in sympatry. The strength of RI needed to achieve sympatry and the subsequent effect of sympatry on RI remain open questions. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
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Pitteloud, Camille, Nils Arrigo, Tomasz Suchan, Alicia Mastretta-Yanes, Roger Vila, Vlad Dincă, Juan Hernández-Roldán, et al. "Climatic niche evolution is faster in sympatric than allopatric lineages of the butterfly genus Pyrgus." Proceedings of the Royal Society B: Biological Sciences 284, no. 1852 (April 12, 2017): 20170208. http://dx.doi.org/10.1098/rspb.2017.0208.
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Understanding how speciation relates to ecological divergence has long fascinated biologists. It is assumed that ecological divergence is essential to sympatric speciation, as a mechanism to avoid competition and eventually lead to reproductive isolation, while divergence in allopatry is not necessarily associated with niche differentiation. The impact of the spatial context of divergence on the evolutionary rates of abiotic dimensions of the ecological niche has rarely been explored for an entire clade. Here, we compare the magnitude of climatic niche shifts between sympatric versus allopatric divergence of lineages in butterflies. By combining next-generation sequencing, parametric biogeography and ecological niche analyses applied to a genus-wide phylogeny of Palaearctic Pyrgus butterflies, we compare evolutionary rates along eight climatic dimensions across sister lineages that diverged in large-scale sympatry versus allopatry. In order to examine the possible effects of the spatial scale at which sympatry is defined, we considered three sets of biogeographic assignments, ranging from narrow to broad definition. Our findings suggest higher rates of niche evolution along all climatic dimensions for sister lineages that diverge in sympatry, when using a narrow delineation of biogeographic areas. This result contrasts with significantly lower rates of climatic niche evolution found in cases of allopatric speciation, despite the biogeographic regions defined here being characterized by significantly different climates. Higher rates in allopatry are retrieved when biogeographic areas are too widely defined—in such a case allopatric events may be recorded as sympatric. Our results reveal the macro-evolutionary significance of abiotic niche differentiation involved in speciation processes within biogeographic regions, and illustrate the importance of the spatial scale chosen to define areas when applying parametric biogeographic analyses.
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Anderson, Sean A. S., and Jason T. Weir. "Character displacement drives trait divergence in a continental fauna." Proceedings of the National Academy of Sciences 118, no. 20 (May 7, 2021): e2021209118. http://dx.doi.org/10.1073/pnas.2021209118.
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Coexisting (sympatric) pairs of closely related species are often characterized by exaggerated trait differences. This widespread pattern is consistent with adaptation for reduced similarity due to costly interactions (i.e., “character displacement”)—a classic hypothesis in evolutionary theory. But it is equally consistent with a community assembly bias in which lineages with greater trait differences are more likely to establish overlapping ranges in the first place (i.e., “species sorting”), as well as with null expectations of trait divergence through time. Few comparative analyses have explicitly modeled these alternatives, and it remains unclear whether trait divergence is a general prerequisite for sympatry or a consequence of interactions between sympatric species. Here, we develop statistical models that allow us to distinguish the signature of these processes based on patterns of trait divergence in closely related lineage pairs. We compare support for each model using a dataset of bill shape differences in 207 pairs of New World terrestrial birds representing 30 avian families. We find that character displacement models are overwhelmingly supported over species sorting and null expectations, indicating that exaggerated bill shape differences in sympatric pairs result from enhanced divergent selection in sympatry. We additionally detect a latitudinal gradient in character displacement, which appears strongest in the tropics. Our analysis implicates costly species interactions as powerful drivers of trait divergence in a major vertebrate fauna. These results help substantiate a long-standing but equivocally supported linchpin of evolutionary theory.
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Borzée, Amaël, and Mi-Sook Min. "Disentangling the Impacts of Speciation, Sympatry and the Island Effect on the Morphology of Seven Hynobius sp. Salamanders." Animals 11, no. 1 (January 14, 2021): 187. http://dx.doi.org/10.3390/ani11010187.
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Closely related individuals from different areas can see their morphologies change based on differences between clades, but also ecological variables such as the island effect or sympatry. This is the case of salamanders, which have adapted to a broad range of ecological niches, ranging from underground dwellers in xeric landscape to tropical arboreal habitats. On the Korean Peninsula, salamanders from the Hynobius clade are widespread on the mainland and islands, with several partially sympatric clades and candidate species. Currently, seven lineages have been identified based on mtDNA, four of them matching named species and three others for which the species status remains untested. While the morphology of Korean Hynobius is known to be variable between genetically segregated clades, we hypothesise that (1) the candidate species are morphologically different, and that (2) the island effect and (3) the sympatric status have significant impacts on the morphology of individuals within the genus. Here we measured 329 Hynobius salamanders from all seven clades, in areas of sympatry and allopatry, and on islands and on the mainland (Graphical Abstract A). We determined that the island effect had a significant impact on the morphology of the genus, with mainland individuals generally displaying a broader range of morphology than islandic individuals (Graphical Abstract B). We also determined that sympatry had an impact on morphology, with the sizes of individuals from clades in sympatric areas diverging from each other (Graphical Abstract C). Finally, we demonstrated that all seven clades have significantly different morphologies, and we described the three candidate species that had already been isolated based on mtDNA and microsatellite data: Hynobius notialis sp. nov., Hynobius geojeensis sp. nov. and Hynobius perplicatus sp. nov. We conclude that looking at morphology alone would be misleading about the true diversity of Hynobius species, and species in general, because of the island and patry effects.
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Bearzi, Maddalena. "Dolphin sympatric ecology." Marine Biology Research 1, no. 3 (July 2005): 165–75. http://dx.doi.org/10.1080/17451000510019132.
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Pfennig, Karin S., and Michael J. Ryan. "Reproductive character displacement generates reproductive isolation among conspecific populations: an artificial neural network study." Proceedings of the Royal Society B: Biological Sciences 273, no. 1592 (February 16, 2006): 1361–68. http://dx.doi.org/10.1098/rspb.2005.3446.
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When interactions with heterospecifics prevent females from identifying conspecific mates, natural selection can promote the evolution of mating behaviours that minimize such interactions. Consequently, mating behaviours may diverge among conspecific populations in sympatry and in allopatry with heterospecifics. This divergence in conspecific mating behaviours—reproductive character displacement—can initiate speciation if mating behaviours become so divergent as to generate reproductive isolation between sympatric and allopatric conspecifics. We tested these ideas by using artificial neural networks to simulate the evolution of conspecific mate recognition in populations sympatric and allopatric with different heterospecifics. We found that advertisement calls diverged among the different conspecific populations. Consequently, networks strongly preferred calls from their own population to those from foreign conspecific populations. Thus, reproductive character displacement may promote reproductive isolation and, ultimately, speciation among conspecific populations.
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Aussavy, M., E. Bernardin, A. Corrigan, J. Hufschmid, and I. Beveridge. "Helminth parasite communities in four species of sympatric macropodids in western Victoria." Australian Mammalogy 33, no. 1 (2011): 13. http://dx.doi.org/10.1071/am10020.
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Helminth parasites of Macropus fuliginosus, M. giganteus, M. rufogriseus and Wallabia bicolor were examined in a region of western Victoria, Australia, where all four species of hosts are sympatric. M. fuliginosus and M. giganteus shared most of their parasites while the helminth communities of M. rufogriseus and W. bicolor were distinctive. The sympatric distribution of the host species studied provides evidence in support of the hypothesis that the differences between the parasite communities of M. fuliginosus–M. giganteus compared with those of M. rufogriseus and W. bicolor are due to parasite specificity rather than to host ecological differences. However, lack of detailed data on the ecological differences of these hosts in areas of sympatry prevents more precise conclusions being drawn on the reasons for the distinctiveness of the parasite communities.
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Bauer, Carolyn M., Adam M. Fudickar, Skylar Anderson-Buckingham, Mikus Abolins-Abols, Jonathan W. Atwell, Ellen D. Ketterson, and Timothy J. Greives. "Seasonally sympatric but allochronic: differential expression of hypothalamic genes in a songbird during gonadal development." Proceedings of the Royal Society B: Biological Sciences 285, no. 1889 (October 24, 2018): 20181735. http://dx.doi.org/10.1098/rspb.2018.1735.
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Allochrony, the mismatch of reproductive schedules, is one mechanism that can mediate sympatric speciation and diversification. In songbirds, the transition into breeding condition and gonadal growth is regulated by the hypothalamic–pituitary–gonadal (HPG) axis at multiple levels. We investigated whether the difference in reproductive timing between two seasonally sympatric subspecies of dark-eyed juncos ( Junco hyemalis ) was related to gene expression along the HPG axis. During the sympatric pre-breeding stage, we measured hypothalamic and testicular mRNA expression of candidate genes via qPCR in captive male juncos. For hypothalamic mRNA, we found our earlier breeding subspecies had increased expression of gonadotropin-releasing hormone ( GnRH ) and decreased expression of androgen receptor, oestrogen receptor alpha and mineralocorticoid receptor ( MR ). Subspecies did not differ in expression of hypothalamic gonadotropin-inhibitory hormone ( GnIH ) and glucocorticoid receptor ( GR ). While our earlier breeding subspecies had higher mRNA expression of testicular GR , subspecies did not differ in testicular luteinizing hormone receptor, follicle-stimulating hormone receptor or MR mRNA expression levels. Our findings indicate increased GnRH production and decreased hypothalamic sensitivity to sex steroid negative feedback as factors promoting differences in the timing of gonadal recrudescence between recently diverged populations. Differential gene expression along the HPG axis may facilitate species diversification under seasonal sympatry.
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Ólafsdóttir, Gudbjörg Á., Michael G. Ritchie, and Sigurdur S. Snorrason. "Positive assortative mating between recently described sympatric morphs of Icelandic sticklebacks." Biology Letters 2, no. 2 (March 6, 2006): 250–52. http://dx.doi.org/10.1098/rsbl.2006.0456.
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Recently, models of sympatric speciation have suggested that assortative mating can develop between sympatric morphs due to divergence in an ecologically important character. For example, in sympatric pairs of threespine stickleback ( Gasterosteus aculeatus L.) size-assortative mating seems to be instrumental in reproductive isolation. Here, we examine courtship behaviour and assortative mating of newly described sympatric stickleback morphs in Lake Thingvallavatn, Iceland. We find that the two morphs show strong positive assortative mating. However, the mechanism involved in mate choice does not seem to be as straightforward as in other similar systems of sympatric stickleback morphs and may involve variation in nest type.
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Singh, B. N., and Sujata Chatterjee. "No character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana." Genome 34, no. 6 (December 1, 1991): 849–52. http://dx.doi.org/10.1139/g91-131.
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To test whether character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana exists, the degree of sexual isolation was measured between their sympatric and allopatric populations. Although the isolation indices vary in different crosses, the average isolation index for sympatric populations is very close to that for allopatric populations. This shows no difference in the degree of sexual isolation between sympatric and allopatric populations of D. bipectinata and D. malerkotliana. Thus there is no evidence for the existence of character displacement for sexual isolation between these two closely related sympatric species.Key words: Drosophila bipectinata, Drosophila malerkotliana, sexual isolation, sympatric and allopatric populations.
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Horwitz, P., M. Adams, and P. Baverstock. "Electrophoretic contributions to the systematics of the freshwater crayfish genus Engaeus Erichson (Decapoda : Parastacidae)." Invertebrate Systematics 4, no. 3 (1990): 615. http://dx.doi.org/10.1071/it9900615.
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As part of an examination into the systematics of the freshwater crayfish genus Engaeus, an electrophoretic evaluation of specimens from a large number of collecting sites has been undertaken. From a total of 76 sample sets, a minimum of 30 distinct biological species have been delineated. Strong evidence from sites of both sympatry and allopatry suggests some further delineations of species but these must await additional discriminatory information. Sympatric species were detected on 11 separate occasions. In each case, fixed allelic differences were found, indicating an absence of interbreeding between each sympatric pair. Allopatric species were delineated where genetic differences between populations exceeded a threshold level determined from observed genetic differences between sympatric Engaeus species and between other (mainly decapod) species in the literature. The results of this analysis have confirmed low levels of heterozygosity in Engaeus species. Frequent isoIation of small populations of Engaeus species, and consequent loss of allelic variation, is suggested as a possible cause of these low levels. Some species have shown variation of allelic frequencies over their geographical range and, in some cases, this variation could be interpreted as showing clinal properties. Finally, the electrophoretic data have been interpreted to produce some information regarding the phylogenetic affinities of delineated species. Several groups of species were found which shared closer intra-group relationships than they did to the other species of Engaeus.
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Bolnick, Daniel I. "WAITING FOR SYMPATRIC SPECIATION." Evolution 58, no. 4 (2004): 895. http://dx.doi.org/10.1554/03-367.
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Bolnick, Daniel I. "WAITING FOR SYMPATRIC SPECIATION." Evolution 58, no. 4 (April 2004): 895–99. http://dx.doi.org/10.1111/j.0014-3820.2004.tb00421.x.
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ELMER, KATHRYN R., and AXEL MEYER. "Sympatric speciation without borders?" Molecular Ecology 19, no. 10 (May 2010): 1991–93. http://dx.doi.org/10.1111/j.1365-294x.2010.04612.x.
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Schliewen, U. K., T. D. Kocher, K. R. McKaye, O. Seehausen, and D. Tautz. "Evidence for sympatric speciation?" Nature 444, no. 7120 (December 2006): E12—E13. http://dx.doi.org/10.1038/nature05419.
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Artemieva, E. A., A. V. Mishchenko, and D. K. Makarov. "Genetic Divergence of the Species of the Yellow Wagtails Group (Passeriformes, Motacillidae) in European Territory of Russia." Vestnik Zoologii 50, no. 3 (June 1, 2016): 279–82. http://dx.doi.org/10.1515/vzoo-2016-0034.
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Abstract Phenotypic and genotypic diversity of populations of species of the yellow wagtails in the space of their ranges in a wide sympatry reflects the mechanisms of reproductive isolation of species and forms of subspecies rank and features of microevolution group - polytypic complex Motacilla flava Linnaeus, 1758. The distribution of species of the yellow wagtails in the European part of Russia is sympatric. The purpose of this study was to investigate whether sympatric settlement led to any genetic separation between the populations of these species. 20 blood samples and 2 samples of eggs collected in areas geographically representing the MID and the southern Russian breeding populations of these species, including all juvenile ringed in 2012, were used. After the polymerase chain reaction (PCR) 4 types of the yellow wagtails group Motacilla flava L., 1758; M. feldegg Michahelles, 1830; M. lutea (S. G. Gmelin, 1774); M. cilreola Pallas, 1776 (Passeriformes, Motacillidae) were sequenced. After aligning the sequences of the gene cytochrome oxidase I, based on the comparison of genetic distances between these species phylogenetic tree of genus Motacilla was constructed. These results suggest that, despite the broad sympatry in nesting places, there is a selective mating between males and females of each species studied in spite of the free crossing and insulating mechanisms in populations.
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Small, Ernest, and L. P. Lefkovitch. "Relationships among morphology, geography, and interfertility in Medicago." Canadian Journal of Botany 64, no. 1 (January 1, 1986): 45–52. http://dx.doi.org/10.1139/b86-009.
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A numerical examination was conducted of the relationships among 99 morphological characters, geographical distribution, and ability to hybridize among the 55 species of the Old World genus Medicago (Leguminosae) currently recognized. Nearest morphological neighbours were found to be much more likely to be crossable than other species combinations. More than half of the species combinations proved to have sympatric geographical ranges. Sympatric species were not found to be significantly more crossable than nonsympatric species. Sympatry was not found to be significantly different in frequency among closely related species than among less closely related species. Using Lefkovitch's measure of biogeographical distance, a positive relationship between morphological divergence and geographical separation was demonstrated. However, the relationship was not strong. This may be due to the very large mean intercentroid distance found between the 54 pairs of nearest morphological neighbours, about 2800 km. This suggests that geographical divergence has developed so extensively between even the most closely related species of Medicago that random species migrations have substantially obscured relationships.
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Capper, Angela, Edwin Cruz-Rivera, Valerie J. Paul, and Ian R. Tibbetts. "Chemical Deterrence of a Marine Cyanobacterium against Sympatric and Non-sympatric Consumers." Hydrobiologia 553, no. 1 (January 2006): 319–26. http://dx.doi.org/10.1007/s10750-005-1129-x.
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Drès, Michele, and James Mallet. "Host races in plant–feeding insects and their importance in sympatric speciation." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 357, no. 1420 (April 29, 2002): 471–92. http://dx.doi.org/10.1098/rstb.2002.1059.
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The existence of a continuous array of sympatric biotypes—from polymorphisms, through ecological or host races with increasing reproductive isolation, to good species—can provide strong evidence for a continuous route to sympatric speciation via natural selection. Host races in plant–feeding insects, in particular, have often been used as evidence for the probability of sympatric speciation. Here, we provide verifiable criteria to distinguish host races from other biotypes: in brief, host races are genetically differentiated, sympatric populations of parasites that use different hosts and between which there is appreciable gene flow. We recognize host races as kinds of species that regularly exchange genes with other species at a rate of more than ca . 1% per generation, rather than as fundamentally distinct taxa. Host races provide a convenient, although admittedly somewhat arbitrary intermediate stage along the speciation continuum. They are a heuristic device to aid in evaluating the probability of speciation by natural selection, particularly in sympatry. Speciation is thereby envisaged as having two phases: (i) the evolution of host races from within polymorphic, panmictic populations; and (ii) further reduction of gene flow between host races until the diverging populations can become generally accepted as species. We apply this criterion to 21 putative host race systems. Of these, only three are unambiguously classified as host races, but a further eight are strong candidates that merely lack accurate information on rates of hybridization or gene flow. Thus, over one–half of the cases that we review are probably or certainly host races, under our definition. Our review of the data favours the idea of sympatric speciation via host shift for three major reasons: (i) the evolution of assortative mating as a pleiotropic by–product of adaptation to a new host seems likely, even in cases where mating occurs away from the host; (ii) stable genetic differences in half of the cases attest to the power of natural selection to maintain multilocus polymorphisms with substantial linkage disequilibrium, in spite of probable gene flow; and (iii) this linkage disequilibrium should permit additional host adaptation, leading to further reproductive isolation via pleiotropy, and also provides conditions suitable for adaptive evolution of mate choice (reinforcement) to cause still further reductions in gene flow. Current data are too sparse to rule out a cryptic discontinuity in the apparently stable sympatric route from host–associated polymorphism to host–associated species, but such a hiatus seems unlikely on present evidence. Finally, we discuss applications of an understanding of host races in conservation and in managing adaptation by pests to control strategies, including those involving biological control or transgenic parasite–resistant plants.
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Head, Josephine S., Martha M. Robbins, Roger Mundry, Loïc Makaga, and Christophe Boesch. "Remote video-camera traps measure habitat use and competitive exclusion among sympatric chimpanzee, gorilla and elephant in Loango National Park, Gabon." Journal of Tropical Ecology 28, no. 6 (November 2012): 571–83. http://dx.doi.org/10.1017/s0266467412000612.
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Abstract:Species commonly exist in sympatry, yet ecological studies are often based on a single species approach while ignoring the impact of sympatric competitors. Over 13 mo we used 24 remote video-camera traps to monitor habitat use of sympatric chimpanzee, gorilla and elephant in four different habitat types in Loango National Park, Gabon. Habitat use by each species was predicted to vary according to seasonal changes in food availability and precipitation. Increased interspecific competition between the three species was expected at times of reduced resource availability, leading to exclusion of the inferior competitor. Supporting the predictions, species abundance per habitat showed seasonal variation: all three species responded positively to increased fruit availability in all habitats, but the response was only significant for gorilla in mature forest and elephant in coastal forest. Responses to rainfall varied, with the chimpanzee responding negatively to rainfall in swamp forest, the gorilla responding positively to rainfall in coastal and secondary forest, and the elephant responding positively to rainfall in mature forest. Elephant presence resulted in competitive exclusion of the apes under certain conditions: the chimpanzee was excluded by the elephant where fruit availability was low, whereas the gorilla was excluded by the elephant in areas of low herb density despite high fruit availability. Our results emphasize the value of applying a multi-species, longer-term approach to studying variation in habitat use among sympatric species and highlight the impact competitors can exert on one another's distribution.
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Bereczki, Judit, Szilárd Póliska, Alex Váradi, and János P. Tóth. "Incipient sympatric speciation via host race formation in Phengaris arion (Lepidoptera: Lycaenidae)." Organisms Diversity & Evolution 20, no. 1 (December 5, 2019): 63–76. http://dx.doi.org/10.1007/s13127-019-00418-y.
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AbstractThe plausibility of sympatric speciation is still debated despite increasing evidence, such as host races in insects. This speciation process may be occurring in the case of the two phenological forms of the obligatorily myrmecophilous Phengaris arion. The main goal of our research was to study the nature and causes of difference between these forms focusing primarily on the incipient speciation via host races. Molecular analyses based on highly variable microsatellites together with Wolbachia screening, male genitalia morphometrics and host ant studies were carried out on four syntopic sample pairs. Our results show that the two phenological forms of P. arion may meet the criteria for host plant races. They coexist in sympatry in certain parts of the species range which is allowed by the adaptation to the distinct phenology of the host plants. Negative selection acts against the intermediate individuals which are on the wing in the inappropriate time frame. Thus, disruptive selection affects and produces bimodal distributions of phenotypes. However, the phenology of food plants is not entirely distinct and fluctuates year by year. Therefore, the two forms can exchange genes occasionally depending on the length of the time slot when they can meet with each other. Consequently, the reproductive isolation could not be completed and the existence of the two arion forms may represent only an incipient stage of sympatric speciation. It is also clear that Wolbachia is likely not a driver of sympatric speciation in this case.
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BARBUTI, ROBERTO, ANDREA MAGGIOLO-SCHETTINI, PAOLO MILAZZO, and ANGELO TROINA. "A METHODOLOGY FOR THE STOCHASTIC MODELING AND SIMULATION OF SYMPATRIC SPECIATION BY SEXUAL SELECTION." Journal of Biological Systems 17, no. 03 (September 2009): 349–76. http://dx.doi.org/10.1142/s0218339009002922.
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In the evolution literature, sympatric speciation is the origin of two, or more, species from a single local population. Many models have been developed to study the role of ecological competition and sexual selection in sympatric speciation. In this paper we propose a methodology for systematically deriving efficient computational models to study speciation in populations evolving with overlapping generations. As a particular case, we consider sympatric speciation by sexual selection and we follow an individual based approach: a population is represented as a set of individuals that can mate and survive according to given probabilities. We use our methodology to construct four different models for sympatric speciation, based on male traits and female preferences. These models differ in the genotypical representation of the individuals. Results of simulations in the different models are shown and discussed. The study of the models show that sympatric speciation by sexual selection is unlikely, also with a favorable distribution of genotypes in the initial population.
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Bolnick, Daniel I. "Sympatric Speciation in Threespine Stickleback: Why Not?" International Journal of Ecology 2011 (2011): 1–15. http://dx.doi.org/10.1155/2011/942847.
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Numerous theoretical models suggest that sympatric speciation is possible when frequency-dependent interactions such as intraspecific competition drive disruptive selection on a trait that is also subject to assortative mating. Here, I review recent evidence that both conditions are met in lake populations of threespine stickleback (Gasterosteus aculeatus). Nonetheless, sympatric speciation appears to be rare or absent in stickleback. If stickleback qualitatively fit the theoretical requirements for sympatric speciation, why do they not undergo sympatric speciation? I present simulations showing that disruptive selection and assortative mating in stickleback, though present, are too weak to drive speciation. Furthermore, I summarize empirical evidence that disruptive selection in stickleback drives other forms of evolutionary diversification (plasticity, increased trait variance, and sexual dimorphism) instead of speciation. In conclusion, core assumptions of sympatric speciation theory seem to be qualitatively reasonable for stickleback, but speciation may nevertheless fail because of (i) quantitative mismatches with theory and (ii) alternative evolutionary outcomes.
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Roldán, M. I., and C. Pla. "Species identification of two sympatric hakes by allozymic markers." Scientia Marina 65, no. 1 (March 30, 2001): 81–84. http://dx.doi.org/10.3989/scimar.2001.65n181.
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