Journal articles on the topic 'Costs of reproduction'
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1
Persson, Jens. "Female wolverine (Gulo gulo) reproduction: reproductive costs and winter food availability." Canadian Journal of Zoology 83, no. 11 (November 1, 2005): 1453–59. http://dx.doi.org/10.1139/z05-143.
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An individual has only a given amount of resources, and therefore an increase in one demographic trait results in a trade-off that necessitates a decrease in a different demographic trait. In general, the main factor determining an individual mammal's reproductive investment is food supply. This study addresses how female wolverine (Gulo gulo (L., 1758)) reproduction is limited. I tested two complementary hypotheses: (1) current reproduction is affected by the costs of reproduction in the preceding year and (2) current reproduction is affected by food availability in the current winter. I addressed the first hypothesis by comparing reproductive rates of females in relation to their reproductive effort in the preceding year. I experimentally tested the second hypothesis by comparing reproductive rates of food-supplemented females versus non-supplemented females. Reproduction incurred costs on female wolverines that affected future reproduction, and reproductive costs appeared to be related to the duration of parental care. Reproduction was higher for food-supplemented females than for non-supplemented females, even though all food-supplemented females had reproduced the preceding year. This study suggests that reproduction is limited by winter food availability and that additional food can compensate for reproductive costs. Thus, I suggest that female wolverine reproduction is determined by their condition in winter, which is a result of the combined effect of reproductive costs and winter food availability.
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Jasienska, Grazyna. "Costs of reproduction and ageing in the human female." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1811 (September 21, 2020): 20190615. http://dx.doi.org/10.1098/rstb.2019.0615.
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Evolutionary theories of ageing point to reproduction as a significant factor to consider when asking why ageing occurs and why there is inter-individual variation in its progression. Reproduction in human females is costly, in terms of energy, nutrients and metabolic adjustments. Thus, it is expected that women who experienced high reproductive effort resulting from multiple reproductive events will age faster. However, the evidence for long-term negative effects of reproduction is not conclusive. The lack of understanding of whether there are trade-offs between reproduction and ageing in women is partly due to methodological challenges. The costs of reproduction are often calculated based only on parity, while other elements contributing to these costs (e.g. breastfeeding, timing of reproduction) are neglected, which may significantly underestimate the total costs and obscure the all-important inter-individual variation in such costs. Costs must be evaluated in relation to individual characteristics, including developmental conditions, nutritional status and social support that a mother receives during reproduction. Furthermore, ageing and health must be assessed based on comprehensive markers rather than arbitrarily assembled variables. Finally, longitudinal rather than cross-sectional studies and new statistical approaches are needed to reveal how much of a decline in health and progressing ageing can actually be attributed to past reproductive processes. This article is part of the theme issue ‘Evolution of the primate ageing process'.
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Cram, Dominic L., Jonathan D. Blount, and Andrew J. Young. "The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder." Proceedings of the Royal Society B: Biological Sciences 282, no. 1819 (November 22, 2015): 20152031. http://dx.doi.org/10.1098/rspb.2015.2031.
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Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence. However, experimental evidence of oxidative costs of reproduction in the wild remains scarce. Here, we use a clutch-removal experiment to investigate the oxidative costs of reproduction in a wild cooperatively breeding bird, the white-browed sparrow weaver, Plocepasser mahali . Our results reveal costs of reproduction that are dependent on group size: relative to individuals in groups whose eggs were experimentally removed, individuals in groups that raised offspring experienced an associated cost (elevated oxidative damage and reduced body mass), but only if they were in small groups containing fewer or no helpers. Furthermore, during nestling provisioning, individuals that provisioned at higher rates showed greater within-individual declines in body mass and antioxidant protection. Our results provide rare experimental evidence that reproduction can negatively impact both oxidative status and body mass in the wild, and suggest that these costs can be mitigated in cooperative societies by the presence of additional helpers. These findings have implications for our understanding of the energetic and oxidative costs of reproduction, and the benefits of cooperation in animal societies.
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Bleu, Josefa, Marlène Gamelon, and Bernt-Erik Sæther. "Reproductive costs in terrestrial male vertebrates: insights from bird studies." Proceedings of the Royal Society B: Biological Sciences 283, no. 1823 (January 27, 2016): 20152600. http://dx.doi.org/10.1098/rspb.2015.2600.
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Reproduction requires resources that cannot be allocated to other functions resulting in direct reproductive costs (i.e. trade-offs between current reproduction and subsequent survival/reproduction). In wild vertebrates, direct reproductive costs have been widely described in females, but their occurrence in males remains to be explored. To fill this gap, we gathered 53 studies on 48 species testing direct reproductive costs in male vertebrates. We found a trade-off between current reproduction and subsequent performances in 29% of the species and in every clade. As 73% of the studied species are birds, we focused on that clade to investigate whether such trade-offs are associated with (i) levels of paternal care, (ii) polygyny or (iii) pace of life. More precisely for this third question, it is expected that fast species (i.e. short lifespan, early maturity, high fecundity) pay a cost in terms of survival, whereas slow species (with opposite characteristics) do so in terms of fecundity. Our findings tend to support this hypothesis. Finally, we pointed out the potential confounding effects that should be accounted for when investigating reproductive costs in males and strongly encourage the investigation of such costs in more clades to understand to what extent our results are relevant for other vertebrates.
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Speakman, John R. "The physiological costs of reproduction in small mammals." Philosophical Transactions of the Royal Society B: Biological Sciences 363, no. 1490 (August 8, 2007): 375–98. http://dx.doi.org/10.1098/rstb.2007.2145.
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Life-history trade-offs between components of fitness arise because reproduction entails both gains and costs. Costs of reproduction can be divided into ecological and physiological costs. The latter have been rarely studied yet are probably a dominant component of the effect. A deeper understanding of life-history evolution will only come about once these physiological costs are better understood. Physiological costs may be direct or indirect. Direct costs include the energy and nutrient demands of the reproductive event, and the morphological changes that are necessary to facilitate achieving these demands. Indirect costs may be optional ‘compensatory costs’ whereby the animal chooses to reduce investment in some other aspect of its physiology to maximize the input of resource to reproduction. Such costs may be distinguished from consequential costs that are an inescapable consequence of the reproductive event. In small mammals, the direct costs of reproduction involve increased energy, protein and calcium demands during pregnancy, but most particularly during lactation. Organ remodelling is necessary to achieve the high demands of lactation and involves growth of the alimentary tract and associated organs such as the liver and pancreas. Compensatory indirect costs include reductions in thermogenesis, immune function and physical activity. Obligatory consequential costs include hyperthermia, bone loss, disruption of sleep patterns and oxidative stress. This is unlikely to be a complete list. Our knowledge of these physiological costs is currently at best described as rudimentary. For some, we do not even know whether they are compensatory or obligatory. For almost all of them, we have no idea of exact mechanisms or how these costs translate into fitness trade-offs.
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Brischoux, François, and Marion Cheron. "Osmotic ‘cost’ of reproduction in breeding male toads." Biology Letters 15, no. 11 (November 2019): 20190689. http://dx.doi.org/10.1098/rsbl.2019.0689.
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Shifts between habitats during reproduction can induce costs that are independent of the reproductive effort and that often apply to both sexes. Such shifts can also illustrate physiological costs complementary to those involving energetic currencies. In this study, we investigated osmotic consequences of reproduction in a context where reproduction induces a shift from terrestrial habitats to freshwater environments. During reproduction, toads migrate to breeding ponds where males remain for several weeks, while females leave shortly after egg-laying. We assessed plasma osmolality of male spined toads during the whole reproductive period (approx. 30 days) in conjunction with markers of individual condition. We found that osmolality decreases during the protracted period of immersion in freshwater during reproduction, presumably through water influx as indicated by body mass changes. Hormonal markers of metabolism and sexual activity were positively correlated with osmolality. Recent research has highlighted hydric ‘costs’ of reproduction when access to water is limited. Our study adds to this growing field of investigation, yet with an opposite perspective, where water availability linked to reproduction provokes hyperhydration rather than dehydration.
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Moger-Reischer, Roy Z., Elizabeth V. Snider, Kelsey L. McKenzie, and Jay T. Lennon. "Low costs of adaptation to dietary restriction." Biology Letters 16, no. 3 (March 2020): 20200008. http://dx.doi.org/10.1098/rsbl.2020.0008.
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Dietary restriction (DR) is the most successful and widespread means of extending organismal lifespan. However, the evolutionary basis of life extension under DR remains uncertain. The traditional evolutionary explanation is that when organisms experience DR, they allocate endogenous resources to survival and postpone reproduction until conditions improve. However, this life-extension strategy should be maladaptive if DR continues for multiple generations due to trade-offs between longevity and reproduction. To test this prediction, we subjected the budding yeast Saccharomyces cerevisiae to 1800 generations of evolution on restricted versus non-restricted diets. Adaptation to a non-restricted diet improved reproductive fitness by 57%, but provided a much smaller (14%) advantage on a restricted diet. By contrast, adaptation to DR resulted in an approximately 35% increase in reproductive fitness on both restricted and non-restricted diets. Importantly, the life-extending effect of DR did not decrease following long-term evolution on the restricted diet. Thus, contrary to theoretical expectations, we found no evidence that the life-extending DR response became maladaptive during multigenerational DR. Together, our results suggest that the DR response has a low cost and that this phenomenon may have evolved as part of a generalist strategy that extends beyond the benefits of postponing reproduction.
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Tatar, Marc, and Daniel E. L. Promislow. "Fitness Costs of Female Reproduction." Evolution 51, no. 4 (August 1997): 1323. http://dx.doi.org/10.2307/2411062.
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Partridge, Linda, and Paul H. Harvey. "Evolutionary biology: Costs of reproduction." Nature 316, no. 6023 (July 1985): 20. http://dx.doi.org/10.1038/316020a0.
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Tatar, Marc, and Daniel E. L. Promislow. "FITNESS COSTS OF FEMALE REPRODUCTION." Evolution 51, no. 4 (August 1997): 1323–26. http://dx.doi.org/10.1111/j.1558-5646.1997.tb03980.x.
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Remick, David. "Measuring the costs of reproduction." Trends in Ecology & Evolution 7, no. 2 (February 1992): 42–45. http://dx.doi.org/10.1016/0169-5347(92)90104-j.
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García-Roa, Roberto, Manuel Serra, and Pau Carazo. "Ageing via perception costs of reproduction magnifies sexual selection." Proceedings of the Royal Society B: Biological Sciences 285, no. 1892 (November 28, 2018): 20182136. http://dx.doi.org/10.1098/rspb.2018.2136.
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Understanding what factors modulate sexual selection intensity is crucial to a wide variety of evolutionary processes. Recent studies show that perception of sex pheromones can severely impact male mortality when it is not followed by mating (perception costs of reproduction). Here, we examine the idea that this may magnify sexual selection by further decreasing the fitness of males with inherently low mating success, hence increasing the opportunity for sexual selection. We use mathematical modelling to show that even modest mortality perception costs can significantly increase variability in male reproductive success under a wide range of demographic conditions. We then conduct a series of assays suggesting that, in Drosophila melanogaster , failure to reproduce early in life may, via perception costs of reproduction, significantly reduces the subsequent fitness of males ( ca 25%), due mostly to increased reproductive ageing. Altogether, our results strongly suggest that perception costs of reproduction can magnify sexual selection in a biologically significant way. Finally, we estimate that around 29% of available studies quantify sexual selection based on short-term fitness estimates that may fail to capture these effects (if they were present in their subject species), and suggest addressing the existence and impact of perception costs of reproduction across taxa should thus be a priority.
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Bogdanowicz, Agnieszka, Paweł Olejniczak, Marlena Lembicz, and Waldemar Żukowski. "Costs of reproduction in life history of a perennial plant Carex secalina." Open Life Sciences 6, no. 5 (October 1, 2011): 870–77. http://dx.doi.org/10.2478/s11535-011-0044-6.
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AbstractWe tested a hypothesis based on life history theory that examines reproductive costs incurred by individuals in consecutive years of their life. A multi-year dataset of resource allocation to vegetative and reproductive structures was analysed in Carex secalina — a perennial, monoecious sedge, reproducing only sexually. In a four-year garden experiment, we assessed above-ground biomass at the end of each season and reproductive allocation expressed as the total length of male and female spikes. The study was aimed at determining how size and age of a plant relates to its reproduction, and how the rate of reproduction affects the year-toyear biomass change in Carex secalina. We observed that after each reproductive episode, individuals had significantly smaller sizes and produced a lower number of generative tillers. The total production of reproductive structures decreased significantly with age in all populations. Moreover, the decrease in plant biomass was greater when more reproductive structures were produced in a previous year, which indicates that the plants incur costs of reproduction in terms of above-ground biomass production.
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Jönsson, K. Ingemar, Juha Tuomi, Johannes Järemo, K. Ingemar Jonsson, and Johannes Jaremo. "Reproductive Effort Tactics: Balancing Pre- and Postbreeding Costs of Reproduction." Oikos 74, no. 1 (October 1995): 35. http://dx.doi.org/10.2307/3545672.
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Morin, A., M. Rughetti, S. Rioux-Paquette, and M. Festa-Bianchet. "Older conservatives: reproduction in female Alpine chamois (Rupicapra rupicapra) is increasingly risk-averse with age." Canadian Journal of Zoology 94, no. 5 (May 2016): 311–21. http://dx.doi.org/10.1139/cjz-2015-0153.
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In long-lived mammals, costs of reproduction may vary with age. The terminal investment hypothesis predicts greater reproductive effort as females approach the end of their life expectancy. We monitored 97 individually marked female Alpine chamois (Rupicapra rupicapra (L., 1758)) between 2007 and 2013 to determine how age-specific reproduction affected body mass and subsequent reproductive success. We captured and weighed females between April and August and monitored reproductive success from April to October through mother–kid associations. Reproductive success was strongly age-dependent and peaked at 70% for prime-aged females (4–7 years). Reproductive senescence began at 8 years, earlier than reported by other studies of ungulates. There was no clear evidence of reproductive costs in any age class. Reproductive success was very heterogeneous for old females, suggesting variability in the onset of senescence. Old females were less likely to reproduce in poor years despite being heavier than prime-aged females, suggesting reproductive restraint in late life rather than terminal investment. Female mass remained stable from May to August with no effect of lactation. Our results suggest that chamois reproductive strategy becomes increasingly conservative with age, resulting in no detectable costs of reproduction.
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Hoffman, Jessica M., Sophie K. Dudeck, Heather K. Patterson, and Steven N. Austad. "Sex, mating and repeatability of Drosophila melanogaster longevity." Royal Society Open Science 8, no. 8 (August 2021): 210273. http://dx.doi.org/10.1098/rsos.210273.
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Costs of reproduction are seemingly ubiquitous across the animal kingdom, and these reproductive costs are generally defined by increased reproduction leading to decreases in other fitness components, often longevity. However, some recent reports question whether reproductive costs exist in every species or population. To provide insight on this issue, we sought to determine the extent to which genetic variation might play a role in one type of reproductive cost—survival—using Drosophila melanogaster . We found, surprisingly, no costs of reproduction nor sex differences in longevity across all 15 genetic backgrounds in two cohorts. We did find significant variation within some genotypes, though these were much smaller than expected. We also observed that small laboratory changes lead to significant changes in longevity within genotypes, suggesting that longevity repeatability in flies may be difficult. We finally compared our results to previously published longevities and found that reproducibility is similar to what we saw in our own laboratory, further suggesting that stochasticity is a strong component of fruit fly lifespan. Overall, our results suggest that there are still large gaps in our knowledge about the effects of sex and mating, as well as genetic background and laboratory conditions on lifespan reproducibility.
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Lambert, Yvan, and Julian J. Dodson. "Freshwater Migration as a Determinant Factor in the Somatic Cost of Reproduction of Two Anadromous Coregonines of James Bay." Canadian Journal of Fisheries and Aquatic Sciences 47, no. 2 (February 1, 1990): 318–34. http://dx.doi.org/10.1139/f90-033.
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We tested the hypothesis that the species-specific costs of migration differentially affect reproductive effort and somatic cost of reproduction in sympatric anadromous populations of cisco (Coregonus artedii) and lake whitefish (C. clupeaformis) of James Bay. Reproductive effort, which includes the energy cost of migration, is higher for cisco. Female cisco allocate more energy to reproduction than its total energy gain. The energy invested by lake whitefish in reproduction is approximately equal to its seasonal energy gain. Reproduction results in large differences in the energy content of gonads, viscera, and carcass between reproductive and nonreproductive fish of the same length. Neither cisco nor lake whitefish are able to spawn two years in succession. The somatic energy increase of reproductive female cisco is 121% lower than the somatic energy increase of nonreproductive females; similar comparisons are 89% (female) and 103% (male) for lake whitefish. The energy cost of migration is largely responsible for the higher somatic cost of reproduction observed for cisco. These different somatic costs of migration are related to resource accumulation prior to migration and to differences in the aerobic cost of swimming between the two species in combination with the difficulty of the freshwater migration.
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Vasilieva, N. A., and A. V. Tchabovsky. "Timing is the only thing: reproduction in female yellow ground squirrels (Spermophilus fulvus)." Canadian Journal of Zoology 92, no. 8 (August 2014): 737–47. http://dx.doi.org/10.1139/cjz-2014-0084.
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Based on 4-year field observations of yellow ground squirrels (Spermophilus fulvus (Lichtenstein, 1823)), we determined whether female reproductive effort, annual reproductive success, and survival were dependent on age, body condition, time of emergence from hibernation, and previous reproduction. The probability of weaning a litter did not vary with female age, body condition, time of emergence, or previous reproduction. Litter size, litter mass, and offspring survival did not vary with age, whereas individual offspring mass was lower in yearlings than in older females. Body condition upon emergence had no effect on litter size, litter mass, offspring mass, and survival. Reproduction did not influence female survival, physical condition upon emergence next spring, or subsequent reproductive efforts. The only factor that affected the extent of reproductive effort and offspring survival was the date of emergence: the later a female emerged, the lower the total and mean offspring mass, and fewer offspring survived. The modulation of reproduction in female S. fulvus by only the timing of vernal emergence and independent of other individual characteristics can be explained by the high costs of missed reproductive opportunity because of short longevity combined with low costs of reproduction when resources are abundant enough to meet both somatic and reproductive needs.
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Schwarzkopf, Lin. "Costs of Reproduction in Water Skinks." Ecology 74, no. 7 (October 1993): 1970–81. http://dx.doi.org/10.2307/1940840.
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Stouffer, Philip C. "Intraseasonal Costs of Reproduction in Starlings." Condor 93, no. 3 (August 1991): 683–93. http://dx.doi.org/10.2307/1368200.
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Santos, P. De Souza, and M. Begon. "Survival Costs of Reproduction in Grasshoppers." Functional Ecology 1, no. 3 (1987): 215. http://dx.doi.org/10.2307/2389423.
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Harvey, Paul H. "Mammalian energetic: Energetic costs of reproduction." Nature 321, no. 6071 (June 1986): 648–49. http://dx.doi.org/10.1038/321648a0.
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Flatt, Thomas. "Survival costs of reproduction in Drosophila." Experimental Gerontology 46, no. 5 (May 2011): 369–75. http://dx.doi.org/10.1016/j.exger.2010.10.008.
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Obeso, Jose Ramon. "The costs of reproduction in plants." New Phytologist 155, no. 3 (September 2002): 321–48. http://dx.doi.org/10.1046/j.1469-8137.2002.00477.x.
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Miller, Tom E. X., Jennifer L. Williams, Eelke Jongejans, Rein Brys, and Hans Jacquemyn. "Evolutionary demography of iteroparous plants: incorporating non-lethal costs of reproduction into integral projection models." Proceedings of the Royal Society B: Biological Sciences 279, no. 1739 (March 14, 2012): 2831–40. http://dx.doi.org/10.1098/rspb.2012.0326.
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Understanding the selective forces that shape reproductive strategies is a central goal of evolutionary ecology. Selection on the timing of reproduction is well studied in semelparous organisms because the cost of reproduction (death) can be easily incorporated into demographic models. Iteroparous organisms also exhibit delayed reproduction and experience reproductive costs, although these are not necessarily lethal. How non-lethal costs shape iteroparous life histories remains unresolved. We analysed long-term demographic data for the iteroparous orchid Orchis purpurea from two habitat types (light and shade). In both the habitats, flowering plants had lower growth rates and this cost was greater for smaller plants. We detected an additional growth cost of fruit production in the light habitat. We incorporated these non-lethal costs into integral projection models to identify the flowering size that maximizes fitness. In both habitats, observed flowering sizes were well predicted by the models. We also estimated optimal parameters for size-dependent flowering effort, but found a strong mismatch with the observed flower production. Our study highlights the role of context-dependent non-lethal reproductive costs as selective forces in the evolution of iteroparous life histories, and provides a novel and broadly applicable approach to studying the evolutionary demography of iteroparous organisms.
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Bleu, Josefa, Manuel Massot, Claudy Haussy, and Sandrine Meylan. "Experimental litter size reduction reveals costs of gestation and delayed effects on offspring in a viviparous lizard." Proceedings of the Royal Society B: Biological Sciences 279, no. 1728 (June 29, 2011): 489–98. http://dx.doi.org/10.1098/rspb.2011.0966.
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Experimental studies have often been employed to study costs of reproduction, but rarely to study costs of gestation. Disentangling the relative importance of each stage of the reproductive cycle should help to assess the costs and benefits of different reproductive strategies. To that end, we experimentally reduced litter size during gestation in a viviparous lizard. We measured physiological and behavioural parameters during gestation and shortly after parturition, as well as survival and growth of females and their offspring. This study showed four major results. First, the experimental litter size reduction did not significantly affect the cellular immune response, the metabolism and the survival of adult females. Second, females with reduced litter size decreased their basking time. Third, these females also had an increased postpartum body condition. As postpartum body condition is positively related to future reproduction, this result indicates a gestation cost. Fourth, even though offspring from experimentally reduced litters had similar weight and size at birth as other offspring, their growth rate after birth was significantly increased. This shows the existence of a maternal effect during gestation with delayed consequences. This experimental study demonstrates that there are some costs to gestation, but it also suggests that some classical trade-offs associated with reproduction may not be explained by gestation costs.
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Huber, Susanne, Eva Millesi, Manfred Walzl, John Dittami, and Walter Arnold. "Reproductive effort and costs of reproduction in female European ground squirrels." Oecologia 121, no. 1 (October 12, 1999): 19–24. http://dx.doi.org/10.1007/s004420050902.
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Kroeger, Svenja B., Daniel T. Blumstein, Kenneth B. Armitage, Jane M. Reid, and Julien G. A. Martin. "Cumulative reproductive costs on current reproduction in a wild polytocous mammal." Ecology and Evolution 8, no. 23 (November 14, 2018): 11543–53. http://dx.doi.org/10.1002/ece3.4597.
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Hayes, Daniel B., and William W. Taylor. "Reproductive Strategy in Yellow Perch (Perca flavescens): Effects of Diet Ontogeny, Mortality, and Survival Costs." Canadian Journal of Fisheries and Aquatic Sciences 47, no. 5 (May 1, 1990): 921–27. http://dx.doi.org/10.1139/f90-106.
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Factors influencing the theoretical optimal age at first reproduction for yellow perch (Perca flavescens) were explored for three different ontogenies including: zooplankton only; zooplankton and benthos; zooplankton, benthos, and fish. Under each of these diets, optimal age at first reproduction decreased as the decrease in mortality caused by reproduction increased. When adult yellow perch fed only on zooplankton, adult survival rate has little effect on optimal age at first reproduction. When fish and benthos are utilized, the optimal age at first reproduction varies strongly with adult survival. Growth rates were affected by both age at maturity and diet ontogeny, with diet ontogeny having a much greater effect. Maximal adult size was affected by reproductive strategy in each case, with larger terminal sizes obtained when maturity was delayed. Increases in size with delayed maturity were greatest when zooplankton, benthos, and fish were available as prey items.
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Blacher, Pierre, Timothy J. Huggins, and Andrew F. G. Bourke. "Evolution of ageing, costs of reproduction and the fecundity–longevity trade-off in eusocial insects." Proceedings of the Royal Society B: Biological Sciences 284, no. 1858 (July 12, 2017): 20170380. http://dx.doi.org/10.1098/rspb.2017.0380.
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Eusocial insects provide special opportunities to elucidate the evolution of ageing as queens have apparently evaded costs of reproduction and reversed the fecundity–longevity trade-off generally observed in non-social organisms. But how reproduction affects longevity in eusocial insects has rarely been tested experimentally. In this study, we took advantage of the reproductive plasticity of workers to test the causal role of reproduction in determining longevity in eusocial insects. Using the eusocial bumblebee Bombus terrestris , we found that, in whole colonies, in which workers could freely ‘choose’ whether to become reproductive, workers' level of ovarian activation was significantly positively associated with longevity and ovary-active workers significantly outlived ovary-inactive workers. By contrast, when reproductivity was experimentally induced in randomly selected workers, thereby decoupling it from other traits, workers' level of ovarian activation was significantly negatively associated with longevity and ovary-active workers were significantly less long-lived than ovary-inactive workers. These findings show that workers experience costs of reproduction and suggest that intrinsically high-quality individuals can overcome these costs. They also raise the possibility that eusocial insect queens exhibit condition-dependent longevity and hence call into question whether eusociality entails a truly reversed fecundity–longevity trade-off involving a fundamental remodelling of conserved genetic and endocrine networks underpinning ageing.
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Berg, V., D. W. Lawson, and A. Rotkirch. "Financial opportunity costs and deaths among close kin are independently associated with reproductive timing in a contemporary high-income society." Proceedings of the Royal Society B: Biological Sciences 287, no. 1919 (January 22, 2020): 20192478. http://dx.doi.org/10.1098/rspb.2019.2478.
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Evolutionary demography predicts that variation in reproductive timing stems from socio-ecologically contingent trade-offs between current and future reproduction. In contemporary high-income societies, the costs and benefits of current reproduction are likely to vary by socioeconomic status (SES). Two influential hypotheses, focusing on the parenthood ‘wage penalty’, and responses to local mortality have separately been proposed to influence the timing of parenthood. Economic costs of reproduction (i.e. income loss) are hypothesized to delay fertility, especially among high childhood SES individuals who experience greater opportunities to build capital through advantageous education and career opportunities. On the other hand, relatively low childhood SES individuals experience higher mortality risk, which may favour earlier reproduction. Here, we examine both hypotheses with a representative register-based, multigenerational dataset from contemporary Finland ( N = 47 678). Consistent with each hypothesis, the predicted financial cost of early parenthood was smaller, and mortality among close kin was higher for individuals with lower childhood SES. Within the same dataset, lower predicted adulthood income and more kin deaths were also independently associated with earlier parenthood. Our results provide a robust demonstration of how economic costs and mortality relate to reproductive timing. We discuss the implications of our findings for demographic theory and public policy.
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Morton, Martin L., Maria E. Pereyra, John D. Crandall, Elizabeth A. MacDougall-Shackleton, and Thomas P. Hahn. "Reproductive Effort and Return Rates in the Mountain White-Crowned Sparrow." Condor 106, no. 1 (February 1, 2004): 131–38. http://dx.doi.org/10.1093/condor/106.1.131.
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AbstractWe analyzed return rates of high-altitude-breeding Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha) in relation to five components of their previous season's reproductive effort: number of fledglings produced, double brooding, number of nesting attempts (first nests plus renests), total number of eggs laid, and fledging date. No relationship of return rate to reproductive effort occurred except in the case of fledging date. Fledging dates spanned a 2-month period from mid-June to mid-August. Returns of females to the study area held steady no matter when their chicks fledged in the previous breeding season, but male return rates increased significantly when their chicks fledged after 20 July. Coincident with that time frame, they entered molt and often withdrew parental care. We hypothesized that males in this montane environment, where thermoregulatory costs are high, traded off reproductive effort (parental care) with survival (return rates). This fits well with models of life-history evolution; however, the corresponding prediction that return rates of females with late-season broods should decrease due to their assumption of greater parental care was not supported. Apparently, the cost of reproduction shifted to the young: late-season nestlings grew more slowly, fledged at a smaller mass, and exhibited a fourfold increase in brood reductions. Their recruitment as breeders in the following season was also greatly reduced. Thus, a cost of reproduction was expressed in two forms, one as changes in survival rates of breeding males, the other as changes in quality of offspring.Esfuerzo Reproductivo y Tasas de Retorno en Zonotrichia leucophrys orianthaResumen. Analizamos las tasas de retorno en las poblaciones reproductivas de alta montaña de Zonotrichia leucophrys oriantha con relación a cinco componentes de su esfuerzo reproductivo de la estación anterior: número de volantones producidos, eventos de dobles nidadas, número de intentos de nidificación (primer nido más re-nidificaciones), número total de huevos puestos y fecha de emplumamiento. No encontramos una relación entre la tasa de retorno y el esfuerzo reproductivo, excepto en el caso de la fecha de emplumamiento. Las fechas de emplumamiento se extendieron por un período de dos meses, desde mediados de junio hasta mediados de agosto. El regreso de las hembras al área de estudio se mantuvo constante, sin importar cuándo los pichones abandonaron el nido en la estación reproductiva anterior, pero las tasas de retorno de los machos incrementaron significativamente cuando sus pichones dejaron el nido luego del 20 de julio. En coincidencia con este momento, los machos comenzaron la muda y frecuentemente dejaron de cuidar a de los pichones. Hipotetizamos que los machos en este ambiente de montaña, donde los costos de termorregulación son altos, canjearon esfuerzo reproductivo (cuidado parental) por supervivencia (tasas de retorno). Esto se ajusta adecuadamente con los modelos de evolución de historias de vida. Sin embargo, la predicción correspondiente de que las tasas de retorno de las hembras con nidadas tardías deberían disminuir debido a la suposición de que brindarían mayor cuidado parental, no fue respaldada. Aparentemente, el costo reproductivo sería trasladado a las crías: los pichones de finales de la estación crecieron más despacio, dejaron el nido con menor masa corporal y exhibieron un incremento de cuatro órdenes de magnitud en la reducción de la nidada. Su reclutamiento como individuos reproductivos en la siguiente estación también se redujo enormemente. De este modo, el costo reproductivo fue expresado de dos formas, una como cambios en las tasas de supervivencia de los machos reproductivos y la otra como cambios en la calidad de la progenie.
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Helle, Samuli, and Virpi Lummaa. "A trade-off between having many sons and shorter maternal post-reproductive survival in pre-industrial Finland." Biology Letters 9, no. 2 (April 23, 2013): 20130034. http://dx.doi.org/10.1098/rsbl.2013.0034.
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A bias in reproduction towards sons, which are energetically more costly than daughters, has been suggested to shorten parental lifespan, but previous results have been mixed. Reproductive costs should be most evident in low rather than high resource settings, and are not expected to be severe in men, because women pay higher direct costs of reproduction. We, therefore, used demographic data from pre-industrial Finland to investigate whether the number of sons and daughters born affected their parents’ post-reproductive survival and whether this was related to parent's resource availability. Irrespective of access to resources, mothers, but not fathers, with many sons suffered from reduced post-reproductive survival, and this association decreased as mothers aged. Our results provide evidence that Finnish mothers traded long post-reproductive lifespan for giving birth to many sons.
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Lind, Martin I., Hanne Carlsson, Elizabeth M. L. Duxbury, Edward Ivimey-Cook, and Alexei A. Maklakov. "Cost-free lifespan extension via optimization of gene expression in adulthood aligns with the developmental theory of ageing." Proceedings of the Royal Society B: Biological Sciences 288, no. 1944 (February 3, 2021): 20201728. http://dx.doi.org/10.1098/rspb.2020.1728.
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Ageing evolves because the force of selection on traits declines with age but the proximate causes of ageing are incompletely understood. The ‘disposable soma’ theory of ageing (DST) upholds that competitive resource allocation between reproduction and somatic maintenance underpins the evolution of ageing and lifespan. In contrast, the developmental theory of ageing (DTA) suggests that organismal senescence is caused by suboptimal gene expression in adulthood. While the DST predicts the trade-off between reproduction and lifespan, the DTA predicts that age-specific optimization of gene expression can increase lifespan without reproduction costs. Here we investigated the consequences for lifespan, reproduction, egg size and individual fitness of early-life, adulthood and post-reproductive onset of RNAi knockdown of five ‘longevity’ genes involved in key biological processes in Caenorhabditis elegans . Downregulation of these genes in adulthood and/or during post-reproductive period increases lifespan, while we found limited evidence for a link between impaired reproduction and extended lifespan. Our findings demonstrate that suboptimal gene expression in adulthood often contributes to reduced lifespan directly rather than through competitive resource allocation between reproduction and somatic maintenance. Therefore, age-specific optimization of gene expression in evolutionarily conserved signalling pathways that regulate organismal life histories can increase lifespan without fitness costs.
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Vézina, François, and Katrina G. Salvante. "Behavioral and physiological flexibility are used by birds to manage energy and support investment in the early stages of reproduction." Current Zoology 56, no. 6 (December 1, 2010): 767–92. http://dx.doi.org/10.1093/czoolo/56.6.767.
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Abstract Interest in phenotypic flexibility has increased dramatically over the last decade, but flexibility during reproduction has received relatively little attention from avian scientists, despite its possible impact on fitness. Because most avian species maintain atrophied reproductive organs when not active, reproduction in birds requires major tissue remodeling in preparation for breeding. Females undergo rapid (days) recrudescence and regression of their reproductive organs at each breeding attempt, while males grow their organs ahead of time at a much slower rate (weeks) and may maintain them at maximal size throughout the breeding season. Reproduction is associated with significant metabolic costs. Egg production leads to a 22%-27% increase in resting metabolic rate (RMR) over non-reproductive values. This is partly due to the activity of the oviduct, an organ that may allow females to adjust reproductive investment by modulating egg size and quality. In males, gonadal recrudescence may lead to a 30% increase in RMR, but the data are inconsistent and general conclusions regarding energetic costs of reproduction in males will require more research. Recent studies on captive female zebra finches describe the impacts of these costs on daily energy budgets and highlight the strategies used by birds to maintain their investment in reproduction when energy is limited. Whenever possible, birds use behavioral flexibility as a first means of saving energy. Decreasing locomotor activity saves energy during challenges such as egg production or exposure to cold temperatures and is an efficient way to buffer variation in individual daily energy budgets. However, when behavioral flexibility is not possible, birds must rely on flexibility at the physiological level to meet energy demands. In zebra finches breeding in the cold, this results in a reduced pace of laying, likely due to down-regulation of both reproductive and non-reproductive function, allowing females to defend minimal egg size and maintain reproductive success. More research involving a range of species in captive and free-living conditions is needed to determine how phenotypic flexibility during tissue remodeling and early reproductive investment translates to natural conditions and affects fitness.
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Belk, Mark C., Peter J. Meyers, and J. Curtis Creighton. "Bigger Is Better, Sometimes: The Interaction between Body Size and Carcass Size Determines Fitness, Reproductive Strategies, and Senescence in Two Species of Burying Beetles." Diversity 13, no. 12 (December 11, 2021): 662. http://dx.doi.org/10.3390/d13120662.
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The cost of reproduction hypothesis suggests that allocation to current reproduction constrains future reproduction. How organisms accrue reproductive costs and allocate energy across their lifetime may differ among species adapted to different resource types. We test this by comparing lifetime reproductive output, patterns of reproductive allocation, and senescence between two species of burying beetles, Nicrophorus marginatus and N. guttula, that differ in body size, across a range of carcass sizes. These two species of burying beetles maximized lifetime reproductive output on somewhat different–sized resources. The larger N. marginatus did better on large and medium carcasses while the smaller N. guttula did best on small and medium carcasses. For both species, reproduction is costly and reproduction on larger carcasses reduced lifespan more than reproduction on smaller carcasses. Carcass size also affected lifetime reproductive strategies. Each species’ parental investment patterns were consistent with terminal investment on carcasses on which they performed best (optimal carcass sizes). However, they exhibited reproductive restraint on carcass sizes on which they did not perform as well. Reproductive senescence occurred largely in response to carcass size. For both species, reproduction on larger carcasses resulted in more rapid senescence. These data suggest that whether organisms exhibit terminal investment or reproductive restraint may depend on type and amount of resources for reproduction.
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Lahdenperä, Mirkka, John Jackson, Win Htut, and Virpi Lummaa. "Capture from the wild has long-term costs on reproductive success in Asian elephants." Proceedings of the Royal Society B: Biological Sciences 286, no. 1912 (October 9, 2019): 20191584. http://dx.doi.org/10.1098/rspb.2019.1584.
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Capturing wild animals is common for conservation, economic or research purposes. Understanding how capture itself affects lifetime fitness measures is often difficult because wild and captive populations live in very different environments and there is a need for long-term life-history data. Here, we show how wild capture influences reproduction in 2685 female Asian elephants ( Elephas maximus ) used in the timber industry in Myanmar. Wild-caught females demonstrated a consistent reduction in breeding success relative to captive-born females, with significantly lower lifetime reproduction probabilities, lower breeding probabilities at peak reproductive ages and a later age of first reproduction. Furthermore, these negative effects lasted for over a decade, and there was a significant influence on the next generation: wild-caught females had calves with reduced survival to age 5. Our results suggest that wild capture has long-term consequences for reproduction, which is important not only for elephants, but also for other species in captivity.
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Descamps, Sébastien, Stan Boutin, Andrew G. McAdam, Dominique Berteaux, and Jean-Michel Gaillard. "Survival costs of reproduction vary with age in North American red squirrels." Proceedings of the Royal Society B: Biological Sciences 276, no. 1659 (December 9, 2008): 1129–35. http://dx.doi.org/10.1098/rspb.2008.1401.
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The costs of reproduction are expected to be higher under unfavourable conditions, so that breeding in years of low food supply should have important costs. In addition, the costs of reproduction may be contingent on the age of individuals, and young growing and old senescent individuals should suffer higher costs than the prime-age ones. We tested these predictions by investigating the costs of reproduction as a function of food availability and age in female North American red squirrels using the long-term data on survival and reproduction. We found that the costs of reproduction were independent of food supply, and we did not detect any trade-off between the current and future reproduction. We also did not detect any survival cost of reproduction for the prime-age females, but found evidence for survival costs in yearlings and old (6 years or above) females with successfully breeding individuals having a lower chance of survival compared with unsuccessful or non-breeding ones. These results supported our prediction that the costs of reproduction depended on the age of female red squirrels and were higher in young growing and old senescent individuals. Our study also indicated that, in contrast to large herbivores, heterogeneity in individual quality and viability selection in red squirrels do not affect the study of trade-offs and of the age variation in life-history traits.
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Nieuwenhuis, Bart P. S., and Timothy Y. James. "The frequency of sex in fungi." Philosophical Transactions of the Royal Society B: Biological Sciences 371, no. 1706 (October 19, 2016): 20150540. http://dx.doi.org/10.1098/rstb.2015.0540.
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Fungi are a diverse group of organisms with a huge variation in reproductive strategy. While almost all species can reproduce sexually, many reproduce asexually most of the time. When sexual reproduction does occur, large variation exists in the amount of in- and out-breeding. While budding yeast is expected to outcross only once every 10 000 generations, other fungi are obligate outcrossers with well-mixed panmictic populations. In this review, we give an overview of the costs and benefits of sexual and asexual reproduction in fungi, and the mechanisms that evolved in fungi to reduce the costs of either mode. The proximate molecular mechanisms potentiating outcrossing and meiosis appear to be present in nearly all fungi, making them of little use for predicting outcrossing rates, but also suggesting the absence of true ancient asexual lineages. We review how population genetic methods can be used to estimate the frequency of sex in fungi and provide empirical data that support a mixed mode of reproduction in many species with rare to frequent sex in between rounds of mitotic reproduction. Finally, we highlight how these estimates might be affected by the fungus-specific mechanisms that evolved to reduce the costs of sexual and asexual reproduction. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’.
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Pierotti, Raymond, and Ian Newton. "Individual Variation and the Costs of Reproduction." Condor 93, no. 4 (November 1991): 1039. http://dx.doi.org/10.2307/3247745.
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Lorente, Maria-Reyes, Juana Hernández, and Fernando Antoñanzas. "Pharmaceutical Costs of Assisted Reproduction in Spain." Clinical Drug Investigation 33, no. 11 (August 23, 2013): 789–94. http://dx.doi.org/10.1007/s40261-013-0123-8.
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Jösson, K. I., and J. Tuomi. "Costs of reproduction in a historical perspective." Trends in Ecology & Evolution 9, no. 8 (August 1994): 304–7. http://dx.doi.org/10.1016/0169-5347(94)90042-6.
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Brooks, Robert, and Michael M. Kasumovic. "Evolution: Exposing the Buried Costs of Reproduction." Current Biology 19, no. 24 (December 2009): R1117—R1119. http://dx.doi.org/10.1016/j.cub.2009.10.065.
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Griffen, BD, ZJ Cannizzo, J. Carver, and M. Meidell. "Reproductive and energetic costs of injury in the mangrove tree crab." Marine Ecology Progress Series 640 (April 23, 2020): 127–37. http://dx.doi.org/10.3354/meps13280.
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Nonlethal injury is a common and ubiquitous feature of marine systems and can result in altered growth and survival rates. Ecological theory predicts that injured animals should face an energetic tradeoff between investing in recovery vs. investing in reproduction. Possible impacts on reproduction may range in magnitude from very strong (elimination of reproduction), to intermediate (reduced number of offspring), to weak (reduced investment in each offspring). While this tradeoff is well established in terrestrial systems, it has received little attention in the marine environment, particularly in a way that quantitatively relates the degree of injury to the degree of reproductive impact. We examined injury via limb loss across 4 sites in the mangrove tree crab Aratus pisonii. We found that limb loss was highest at the site that was closest to roads and had the highest level of human presence, and conversely, injury was lowest at the site furthest from the road and with the lowest level of human presence. We found evidence that the quality of consumed food likely decreases with the number of limbs lost, but found no influence of limb loss on amount of food consumed or on energy storage. We show that limb loss reduced the number of eggs produced and that the mass of the ovary declined with the number of regenerating limbs, providing direct evidence for a tradeoff between reproduction and injury recovery. Further, our study therefore suggests that these impacts may increase with the level of human disturbance.
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Bell, M. B. V., H. J. Nichols, J. S. Gilchrist, M. A. Cant, and S. J. Hodge. "The cost of dominance: suppressing subordinate reproduction affects the reproductive success of dominant female banded mongooses." Proceedings of the Royal Society B: Biological Sciences 279, no. 1728 (July 13, 2011): 619–24. http://dx.doi.org/10.1098/rspb.2011.1093.
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Social species show considerable variation in the extent to which dominant females suppress subordinate reproduction. Much of this variation may be influenced by the cost of active suppression to dominants, who may be selected to balance the need to maximize the resources available for their own offspring against the costs of interfering with subordinate reproduction. To date, the cost of reproductive suppression has received little attention, despite its potential to influence the outcome of conflict over the distribution of reproduction in social species. Here, we investigate possible costs of reproductive suppression in banded mongooses, where dominant females evict subordinates from their groups, thereby inducing subordinate abortion. We show that evicting subordinate females is associated with substantial costs to dominant females: pups born to females who evicted subordinates while pregnant were lighter than those born after undisturbed gestations; pups whose dependent period was disrupted by an eviction attained a lower weight at independence; and the proportion of a litter that survived to independence was reduced if there was an eviction during the dependent period. To our knowledge, this is the first empirical study indicating a possible cost to dominants in attempting to suppress subordinate breeding, and we argue that much of the variation in reproductive skew both within and between social species may be influenced by adaptive variation in the effort invested in suppression by dominants.
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Sand, Håkan. "Costs of reproduction in female moose (Alces alces) as measured by means of phenotypic correlations." Canadian Journal of Zoology 76, no. 1 (January 1, 1998): 187–93. http://dx.doi.org/10.1139/z97-181.
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The costs of pregnancy and lactation in terms of subsequent body growth and fecundity were studied by comparing different reproductive categories of Swedish female moose (Alces alces) during 1989-1992. Non-reproducing females and females that experienced gestation but not lactation were significantly heavier than females in the same reproductive category prior to reproduction. Production of one offspring and subsequent lactation during the summer and early autumn were also associated with an average annual increase in carcass mass, although this was less pronounced than in females that only experienced gestation. By contrast, production of two offspring and successful rearing of both to the autumn resulted, on average, in a reduction of carcass mass (7%) relative to that of females in the same reproductive category prior to reproduction. In female moose, while body growth was affected by the costs of lactation, future fecundity was not. Instead, future fecundity was related most strongly to the number of offspring produced during the current year. This positive association could not be attributed to variation in individual quality in terms of age or carcass mass. The ultimate consequences of reproduction in female moose seem to strongly influence the patterns of growth: adult females will alternate between gain and loss of body mass among years, depending on the number of offspring produced and successfully reared through the lactation phase.
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Sawecki, Jacob, Emily Miros, Shana E. Border, and Peter D. Dijkstra. "Reproduction and maternal care increase oxidative stress in a mouthbrooding cichlid fish." Behavioral Ecology 30, no. 6 (August 16, 2019): 1662–71. http://dx.doi.org/10.1093/beheco/arz133.
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Abstract Investment in reproduction and postzygotic parental care is an energetically costly yet fundamental aspect of the life-history strategies in many species. Recently, oxidative stress has received attention as a potential mediator in the trade-off between reproduction, growth, and survival. During activities that increase metabolic activity, such as providing offspring care, an overproduction of reactive oxygen species can occur that cannot be counteracted by antioxidants, leading to oxidative stress and tissue damage. Here, we investigated the oxidative costs of reproduction and maternal care over the course of the reproductive cycle in a mouthbrooding cichlid fish within socially stable and unstable environments. We manipulated social stability by disrupting the habitat in socially unstable tanks. We expected to see an increase in the burden of maternal care within unstable environments due to increased male harassment of females as a byproduct of increased male–male aggression. We found that brooding females have higher levels of oxidative stress than nonbrooding females and oxidative stress fluctuates throughout the reproductive cycle. These fluctuations were driven by a spike in reactive oxygen metabolites at the beginning of brood care followed by an increase in antioxidant defense. Surprisingly, the link between reproduction and oxidative stress was not different between females from stable or unstable environments. Our study illustrates a more complete picture of the physiological costs of reproduction and parental care throughout different stages of care rather than a simplistic end-point observation of how reproduction and parental care affect an individual.
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Hasegawa, Shigeaki, and Hiroshi Takeda. "Functional specialization of current shoots as a reproductive strategy in Japanese alder (Alnus hirsuta var. sibirica)." Canadian Journal of Botany 79, no. 1 (January 1, 2001): 38–48. http://dx.doi.org/10.1139/b00-143.
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Current shoots, which form the crown of a tree, are specialized in various functions such as crown expansion, reproduction, and assimilation. We examined the temporal and spatial distribution of reproductive shoots in Alnus hirsuta Turcz. var. sibirica (Fischer) C.K. Schn., assessed their direct and indirect costs of reproduction, and explained their distribution in the crown as the reproductive strategy of a current shoot population. The upper and lower limits to the lengths of current shoots for reproductive growth (flower formation) were 40 and 10 cm, respectively. Reproductive 1-year-old shoots produced fewer shoots in the following year than non-reproductive 1-year-old shoots. In current shoots longer than 40 cm, the increment of reproductive output in the following year by abandonment of reproduction surpassed the decrement of reproductive output in the current year by abandonment of reproduction. This may be one reason for the upper limit of reproductive shoot length. Thus, the current shoot population of A. hirsuta var. sibirica may be divided into three functionally specialized subpopulations: reproductive, maintenance, and exploratory. This specialization is considered to be a reproductive strategy to maximize their lifetime reproductive success.Key words: current shoot population, reproductive ecology, functional specialization, cost of reproduction, Japanese alder.
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Wheelwright, Nathaniel T., Joanna Leary, and Caragh Fitzgerald. "The costs of reproduction in tree swallows (Tachycineta bicolor)." Canadian Journal of Zoology 69, no. 10 (October 1, 1991): 2540–47. http://dx.doi.org/10.1139/z91-358.
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We investigated the effect of brood size on nestling growth and survival, parental survival, and future fecundity in tree swallows (Tachycineta bicolor) over a 4-year period (1987–1990) in an effort to understand whether reproductive trade-offs limit clutch size in birds. In addition to examining naturally varying brood sizes in a population on Kent Island, New Brunswick, Canada, we experimentally modified brood sizes, increasing or decreasing the reproductive burdens of females by two offspring. Unlike previous studies, broods of the same females were enlarged or reduced in up to 3 successive years in a search for evidence of cumulative costs of reproduction that might go undetected by a single brood manipulation. Neither observation nor experiment supported the existence of a trade-off between offspring quality and quantity, in contrast with the predictions of life-history theory. Nestling wing length, mass, and tarsus length were unrelated to brood size. Although differences between means were in the direction predicted, few differences were statistically significant, despite large sample sizes. Nestlings from small broods were no more likely to return as breeding adults than nestlings from large broods, but return rates of both groups were very low. Parental return rates were also independent of brood size, and there was no evidence of a negative effect of brood size on future fecundity (laying date, clutch size). Reproductive success, nestling size, and survival did not differ between treatments for females whose broods were manipulated in successive years. Within the range of brood sizes observed in this study, the life-history costs of feeding one or two additional nestlings in tree swallows appear to be slight and cannot explain observed clutch sizes. Costs not measured in this study, such as the production of eggs or postfledging parental care, may be more important in limiting clutch size in birds.
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Mesa, Ernesto González, and José Alberto Herrera Peral. "Incidence and Costs of Multifetal Pregnancies in Andalusia (2000–2010)." Twin Research and Human Genetics 14, no. 5 (October 1, 2011): 484–89. http://dx.doi.org/10.1375/twin.14.5.484.
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In the past 50 years the incidence of multiple pregnancies has increased dramatically due almost exclusively to two factors: delayed childbearing and assisted reproductive techniques. In this paper we analyze the variations in the incidence of multiple gestations in Andalusia, one of the biggest administrative regions in Spain, over the last decade. Assisted reproduction techniques are very often evaluated only in terms of implantation and pregnancy rates per cycle, ignoring everything related to complications of multiple births, prematurity or economic overload. The rate of twins in Andalusia has increased from 10.9 per thousand in 2000 to 16.2 per thousand in 2009. The rate of triplet births has also increased in recent years. After a decline in 2003, motivated by promulgation of the first Human Assisted Reproduction Law, there was an increase after a second law came into effect in 2006. Health care spending attributable to the excess of multiple pregnancies reported in the decade 2000–2010 may have been much higher than €25 million.