共查询到20条相似文献，搜索用时 15 毫秒
1.
Christopher M. Schalk 《Austral ecology》2016,41(4):409-416
Adaptive phenotypic plasticity is widespread and involves diverse phenotypes. Key environmental stressors, such as predation risk, can simultaneously induce changes in multiple traits, but the magnitude of response is dependent upon the environmental conditions. Species that utilize temporary ponds are expected to exhibit stronger predator‐induced responses in the form of morphology than behaviour (i.e. reduced activity) to meet the demands of rapid development by maintaining high foraging activity while reducing predation risk via morphologically plastic traits. In a laboratory experiment, I examined the effects of predator chemical cues and conspecific alarm cues on activity, development and morphology on Leptodactylus bufonius tadpoles. This species has terrestrial oviposition and completes the early part of its development outside of ephemeral and temporary ponds in the Gran Chaco ecoregion of South America. Tadpoles in the predator treatments exhibited both behavioural and morphological predator‐induced plastic responses. Tadpoles tended to possess shorter, deeper tails when exposed to predators. The greatest reduction in activity was observed in tadpoles exposed to both predator and conspecific alarm cues, which subsequently resulted in the slowest development. Temporary and ephemeral pond adapted species with terrestrial oviposition may capitalize on a head start in development by being able to afford reduced growth rates via a reduction in activity. This may occur when the constraints imposed by pond hydroperiod (e.g. risk of pond drying) are relaxed when compared with species with aquatic oviposition, which must undergo all stages of development during the pond's hydroperiod. Thus, in addition to the predator and hydroperiod gradients, examining phenotypically plastic responses along a ‘terrestriality gradient’ in a comparative framework would provide insights as to the costs and benefits of increasing terrestriality in anuran reproductive modes to environmental stressors. 相似文献
2.
Reproductive traits differ between intralacustrine Arctic charr morphs. Here, we examine three sympatric lacustrine Arctic charr morphs with respect to fecundity, egg size and spawning time/site to assess reproductive investments and trade‐offs, and possible fitness consequences. The littoral omnivore morph (LO‐morph) utilizes the upper water for feeding and reproduction and spawn early in October. The large profundal piscivore morph (PP‐morph) and the small profundal benthivore morph (PB‐morph) utilize the profundal habitat for feeding and reproduction and spawn in December and November, respectively. Females from all morphs were sampled for fecundity and egg‐size analysis. There were large differences between the morphs. The PB‐morph had the lowest fecundity (mean = 45, SD = 13) and smallest egg size (mean = 3.2 mm, SD = 0.32 mm). In contrast, the PP‐morph had the highest fecundity (mean = 859.5, SD = 462) and the largest egg size (mean = 4.5 mm, SD = 0.46 mm), whereas the LO‐morph had intermediate fecundity (mean = 580, SD = 225) and egg size (mean = 4.3, SD = 0.24 mm). Fecundity increased with increasing body size within each morph. This was not the case for egg size, which was independent of body sizes within morph. Different adaptations to feeding and habitat utilization have apparently led to a difference in the trade‐off between fecundity and egg size among the three different morphs. 相似文献
3.
James P. Dines Sarah L. Mesnick Katherine Ralls Laura May‐Collado Ingi Agnarsson Matthew D. Dean 《Evolution; international journal of organic evolution》2015,69(6):1560-1572
Mating with multiple partners is common across species, and understanding how individual males secure fertilization in the face of competition remains a fundamental goal of evolutionary biology. Game theory stipulates that males have a fixed budget for reproduction that can lead to a trade‐off between investment in precopulatory traits such as body size, armaments, and ornaments, and postcopulatory traits such as testis size and spermatogenic efficiency. Recent theoretical and empirical studies have shown that if males can monopolize access to multiple females, they will invest disproportionately in precopulatory traits and less in postcopulatory traits. Using phylogenetically controlled comparative methods, we demonstrate that across 58 cetacean species with the most prominent sexual dimorphism in size, shape, teeth, tusks, and singing invest significantly less in relative testes mass. In support of theoretical predictions, these species tend to show evidence of male contests, suggesting there is opportunity for winners to monopolize access to multiple females. Our approach provides a robust dataset with which to make predictions about male mating strategies for the many cetacean species for which adequate behavioral observations do not exist. 相似文献
4.
- Life‐history strategies are known to shift with latitude in many species. While life‐history variation related to body size, reproductive investment, and behavior has been studied for years, another crucial life‐history component is the immune system, which can influence an animal's survival.
- We measured selected life‐history traits in side‐blotched lizards in southern Utah and Oregon in the field for two consecutive years and conducted a common‐garden experiment in the laboratory to determine how organisms from different latitudes optimize either immunity or reproduction. We observed lizards from southern populations, which are known to be shorter‐lived, had lower immune function during reproduction when compared to northern lizards in 2012, but the relationship reversed in the following year.
- Our laboratory study revealed that southern lizards healed cutaneous wounds faster and had higher microbiocidal ability when compared to their northern counterparts, but lost mass doing so. The northern lizards ate more than the southern ones and maintained their body mass. It is possible that northern lizards are better adapted to taking advantage of available food resources. Alternatively, southern lizards may have exhibited sickness behavior in response to an immune challenge or reacted more strongly to the stress of captivity.
- We found differences in life‐history strategies used by animals from different latitudes, and that these changes can shift within a population depending on the weather conditions of the year. Furthermore, when taken from the field and placed into a common‐garden environment, some of these differences in strategy appear to be intrinsic to the animals (i.e., whether they came from southern or northern populations).
5.
Kaczmarczyk AN Kopp A 《BioEssays : news and reviews in molecular, cellular and developmental biology》2011,33(1):5-12
We suggest that the commonly observed trade-offs between early- and late-life reproduction may be mediated by genetic variation in germline stem cell maintenance. Stem cell biology provides a natural framework and experimental methods for understanding the mechanistic basis of life-history evolution. At the same time, natural variation in life-history strategies can serve as a powerful tool for identifying the genes and molecular pathways involved in the maintenance of stem cells in aging adults. We illustrate the connections between life-history and stem cells with examples drawn primarily from Drosophila melanogaster and Caenorhabditis elegans, and suggest a number of testable hypotheses and avenues for future investigation that can be addressed with existing models and tools. 相似文献
6.
Kristin R. Duffield Kylie J. Hampton Thomas M. Houslay John Hunt James Rapkin Scott K. Sakaluk Ben M. Sadd 《Evolution; international journal of organic evolution》2018,72(3):578-589
The terminal investment hypothesis proposes that decreased expectation of future reproduction (e.g., arising from a threat to survival) should precipitate increased investment in current reproduction. The level at which a cue of decreased survival is sufficient to trigger terminal investment (i.e., the terminal investment threshold) may vary according to other factors that influence expectation for future reproduction. We test whether the terminal investment threshold varies with age in male crickets, using heat‐killed bacteria to simulate an immune‐inducing infection. We measured calling effort (a behavior essential for mating) and hemolymph antimicrobial activity in young and old males across a gradient of increasing infection cue intensity. There was a significant interaction between the infection cue and age in their effect on calling effort, confirming the existence of a dynamic terminal investment threshold: young males reduced effort at all infection levels, whereas old males increased effort at the highest levels relative to naïve individuals. A lack of a corresponding decrease in antibacterial activity suggests that altered reproductive effort is not traded against investment in this component of immunity. Collectively, these results support the existence of a dynamic terminal investment threshold, perhaps accounting for some of the conflicting evidence in support of terminal investment. 相似文献
7.
Alexander Kotrschal Alberto Corral‐Lopez Sönke Szidat Niclas Kolm 《Evolution; international journal of organic evolution》2015,69(11):3013-3020
One key hypothesis in the study of brain size evolution is the expensive tissue hypothesis; the idea that increased investment into the brain should be compensated by decreased investment into other costly organs, for instance the gut. Although the hypothesis is supported by both comparative and experimental evidence, little is known about the potential changes in energetic requirements or digestive traits following such evolutionary shifts in brain and gut size. Organisms may meet the greater metabolic requirements of larger brains despite smaller guts via increased food intake or better digestion. But increased investment in the brain may also hamper somatic growth. To test these hypotheses we here used guppy (Poecilia reticulata) brain size selection lines with a pronounced negative association between brain and gut size and investigated feeding propensity, digestive efficiency (DE), and juvenile growth rate. We did not find any difference in feeding propensity or DE between large‐ and small‐brained individuals. Instead, we found that large‐brained females had slower growth during the first 10 weeks after birth. Our study provides experimental support that investment into larger brains at the expense of gut tissue carries costs that are not necessarily compensated by a more efficient digestive system. 相似文献
8.
James F. Harwood Kehui Chen Pablo Liedo Hans‐Georg Müller Jane‐Ling Wang Amy E. Morice James R. Carey 《Physiological Entomology》2015,40(1):65-71
Hypotheses exploring the influence of dietary conditions on the life‐history trade‐off between survival and reproductive success are extensively tested in female insects but only rarely explored in males. The present study examines the impact of dietary quality and female access on age‐specific reproduction and survival of the male Mexican fruit fly Anastrepha ludens Loew (Diptera: Tephritidae). There is a clear cost of female access for males with access to dietary protein, measurable as a decrease in life expectancy, which is further influenced by the age when females are introduced. A protein deficient diet reduces the lifespan benefit of virginity and masks the detrimental effect of female access on male life expectancy. Dietary protein is not necessary for reproductive success, although access to protein at eclosion improves the lifetime reproductive success of males compared to when it is delayed. Overall, reproductive success diminishes as the male flies age, regardless of the dietary conditions, providing evidence for reproductive senescence in males. Delaying the males' access to a protein source fails to influence the negative effect of age on reproductive ability. Because age‐specific reproductive rates decline with age, regardless of diet, male fitness does not benefit from lifespan extension. Therefore, males can be expected to allocate available resources towards reproductive effort in favour of an extended lifespan, regardless of mate and protein availability. 相似文献
9.
Kyle M. Benowitz Ashley U. Amukamara Elizabeth C. Mckinney Allen J. Moore 《Ecological Entomology》2019,44(1):11-16
1. Burying beetles (Nicrophorus spp.) provide an excellent model system to test predictions about the relationships between environment, life‐history and behaviour. All species in the genus display similar natural histories, breeding on vertebrate carcasses and providing parental care to developing offspring. However, variations in other aspects of species' ecologies provide a rich framework to examine the evolution of parental behaviours and other traits. 2. One little‐studied species, N. sayi, breeds in substantially colder temperatures than its congeners, creating a potentially harsh environment for offspring. Here, we examined the timing of reproductive and developmental events in this species, and also investigated the effects of removing parents on offspring performance. 3. We find that development is not only extremely slow in this species, but it is also delayed even in comparison to other burying beetles reared at similar temperatures. However, the presence of parents reduces the time that offspring take to leave the carcass. This decrease in development time does not appear to result in a trade‐off with mortality or body size. 4. From these results, we suggest that very slow development may be advantageous when living in a particularly cold environment. Additionally, one role of extended parental care may be to assist offspring in dealing with these harsh conditions, and to mitigate the potentially negative consequences of adopting such a slow life‐history strategy. 相似文献
10.
L. Santos‐del‐Blanco S. P. Bonser F. Valladares M. R. Chambel J. Climent 《Journal of evolutionary biology》2013,26(9):1912-1924
A plastic response towards enhanced reproduction is expected in stressful environments, but it is assumed to trade off against vegetative growth and efficiency in the use of available resources deployed in reproduction [reproductive efficiency (RE)]. Evidence supporting this expectation is scarce for plants, particularly for long‐lived species. Forest trees such as Mediterranean pines provide ideal models to study the adaptive value of allocation to reproduction vs. vegetative growth given their among‐population differentiation for adaptive traits and their remarkable capacity to cope with dry and low‐fertility environments. We studied 52 range‐wide Pinus halepensis populations planted into two environmentally contrasting sites during their initial reproductive stage. We investigated the effect of site, population and their interaction on vegetative growth, threshold size for female reproduction, reproductive–vegetative size relationships and RE. We quantified correlations among traits and environmental variables to identify allocation trade‐offs and ecotypic trends. Genetic variation for plasticity was high for vegetative growth, whereas it was nonsignificant for reproduction. Size‐corrected reproduction was enhanced in the more stressful site supporting the expectation for adverse conditions to elicit plastic responses in reproductive allometry. However, RE was unrelated with early reproductive investment. Our results followed theoretical predictions and support that phenotypic plasticity for reproduction is adaptive under stressful environments. Considering expectations of increased drought in the Mediterranean, we hypothesize that phenotypic plasticity together with natural selection on reproductive traits will play a relevant role in the future adaptation of forest tree species. 相似文献
11.
Telomere dynamics in natural populations have been linked to survival, reproduction, and energetic investment. Given their putative role in mediating life‐history trade‐offs, telomeres are also a likely candidate for maintaining honesty in sexually selected signals; few studies to date, however, have demonstrated a correlation between sexual signals and telomere dynamics. Here, we show that plumage coloration in male common yellowthroats (Geothlypis trichas) is correlated with both relative telomere length and with the rate of telomere loss between years. Elevated antioxidant capacity is also associated with reduced telomere loss, but only among older males. Previous work in this population has demonstrated that males with brighter plumage are in better condition, have higher reproductive success, and are more likely to survive over winter. Thus, the signal attribute associated with mate choice in this system also conveys reliable information about telomere dynamics. At present, it is unclear whether telomere maintenance plays a causal role in maintaining signal honesty or whether the correlation arises due to underlying variation in individual resources or genotypes. We suggest that subsequent work should consider the possibility that fundamental trade‐offs between signal investment and cell‐level processes that influence aging and reproductive senescence may provide a foundation for understanding the maintenance of sexual signal honesty. 相似文献
12.
JOFFREY MOIROUX CÉCILE LE LANN MAJEED A. SEYAHOOEI PHILIPPE VERNON JEAN‐SÉBASTIEN PIERRE JOAN VAN BAAREN JACQUES J. M. VAN ALPHEN 《Ecological Entomology》2010,35(6):727-736
1. Climate is an important source of selection on life histories, and local adaptations to climate have been described in several cline studies. Temperature is the main climatic factor that has been considered as an agent of selection, whereas other factors may vary with it, such as precipitation. 2. We compared life‐history traits of five populations of Leptopilina boulardi, a Drosophila parasitoid, originating from contrasting climates. Referring to cline studies, we hypothesised shorter lifespan, earlier reproduction, and lower lipid content in populations from the hottest and driest areas if life histories have been selected in response to temperature and/or humidity. 3. Our results are opposite to these predictions. Females from humid and mild climates invested more in early reproduction and lived for fewer days than females from dry and hot areas, which were synovigenic (i.e. they matured additional eggs during adult life) and able to synthesise lipids during adult life. 4. We suggest that life histories are more adapted to host distribution than to climatic factors. Drosophila patches are more abundant in the humid area, allowing the parasitoids to spend less energy and time finding hosts. This may result in selection for early reproduction traded‐off against longevity. In the hot and dry climate, females have to fly large distances to find host patches. Synovigeny, a long lifespan, lipogenesis, and high dispersal ability may be adaptive there. This is the first time that between‐population differences in the ability to synthesise lipids have been described in parasitoids. 相似文献
13.
Abstract Most studies of insect reproductive allocation concentrate on propagule size and number and very few consider egg composition, which is likely to be equally important. In the present study, data are provided on changes in egg lipid, glycogen, free carbohydrate and protein during embryonic development of the aphidophagous ladybird Adalia bipunctata (L.) and the compositions of A. bipunctata, Adalia decempunctata and Anisosticta novemdecimpunctata eggs are compared. In A. bipunctata, egg mass, lipid and glycogen decline strongly during development and egg protein declines more weakly. Free carbohydrate declines early in egg development and increases at egg hatching. Lipid is energetically the most important developmental fuel, although approximately half of the initial egg lipid remains in the neonate larva. Across the three species, energy per unit egg mass is lowest in the least specialized species, A. bipunctata, which also has the largest eggs, and is highest in the most specialized, An. novemdecimpunctata, which has the smallest eggs. Two possible explanations for the observed pattern are discussed: (i) species laying smaller eggs may incur higher developmental costs per unit mass than species laying larger eggs and (ii) more specialized species, which reproduce at lower aphid densities, may provision neonate larvae better to facilitate location and capture of aphids. 相似文献
14.
Ultraviolet (UV) light is a major cause of stress, mutation, and mortality in microorganisms, causing numerous forms of cellular damage. Nevertheless, there is tremendous variation within and among bacterial species in their sensitivity to UV light. We investigated direct and correlated responses to selection during exposure to UV. Replicate lines of Escherichia coli K12 were propagated for 600 generations, half with UV and half as a control without UV. All lines responded to selection, and we found strong positive and negative correlated responses to selection associated with increased UV resistance. Compared to Control populations, UV-selected populations increased in desiccation and starvation resistance approximately twofold but were 10 times more sensitive to hypersalinity. There was little evidence for a persistent large competitive fitness cost to UV resistance. These results suggest that natural variation in UV resistance may be maintained by trade-offs for resistance to other abiotic sources of mortality. We observed an average twofold increase in cell size by the UV-selected populations, consistent with a structural mode of adaptation to UV exposure having preadaptive and maladaptive consequences to other abiotic stresses. 相似文献
15.
16.
Vanika Gupta Saudamini Venkatesan Martik Chatterjee Zeeshan A. Syed Vaishnavi Nivsarkar Nagaraj G. Prasad 《Evolution; international journal of organic evolution》2016,70(4):934-943
Maintenance and deployment of the immune system are costly and are hence predicted to trade‐off with other resource‐demanding traits, such as reproduction. We subjected this longstanding idea to test using laboratory experimental evolution approach. In the present study, replicate populations of Drosophila melanogaster were subjected to three selection regimes—I (Infection with Pseudomonas entomophila), S (Sham‐infection with MgSO4), and U (Unhandled Control). After 30 generations of selection flies from the I regime had evolved better survivorship upon infection with P. entomophila compared to flies from U and S regimes. However, contrary to expectations and previous reports, we did not find any evidence of trade‐offs between immunity and other life history related traits, such as longevity, fecundity, egg hatchability, or development time. After 45 generations of selection, the selection was relaxed for a set of populations. Even after 15 generations, the postinfection survivorship of populations under relaxed selection regime did not decline. We speculate that either there is a negligible cost to the evolved immune response or that trade‐offs occur on traits such as reproductive behavior or other immune mechanisms that we have not investigated in this study. Our research suggests that at least under certain conditions, life‐history trade‐offs might play little role in maintaining variation in immunity. 相似文献
17.
Life-history theory suggests that energetically expensive traits may trade off against each other, resulting in costs associated with the development or maintenance of a particular phenotype. The deployment of resistance mechanisms during parasite exposure is one such trait, and thus their potential benefit in fighting off parasites may be offset by costs to other fitness-related traits. In this study, we used trade-off theory as a basis to test whether stimulating an increased development rate in juvenile Daphnia would reveal energetic constraints to its ability to resist infection upon subsequent exposure to the castrating parasite, Pasteuria ramosa. We show that the presumably energetically expensive process of increased development rate does result in more infected hosts, suggesting that parasite resistance requires the allocation of resources from a limited source, and thus has the potential to be costly. 相似文献
18.
19.
Energetically demanding migrations may impact the resources available for reproductive trait development and activity, and hence favour evolution of new investment strategies for remaining resources. We conducted a large-scale experiment to evaluate the proximate cost of migration on male reproductive investment in chinook salmon (Oncorhynchus tshawytscha) and contemporary evolution of reproductive allocation. Experimentally induced differences in migratory costs (17 km inland and 17 m elevation vs. 100 km and 430 m) influenced dorsal hump size and upper jaw length, two traits influencing male mating success that are developed during migration. Longer migration also reduced tissue energy reserves available for competition and length of breeding life. Corresponding shifts in the balance between natural and sexual selection appear to have been responsible for heritable population divergence in secondary sexual trait investment, in approximately 26 generations, following colonization of spawning sites with different migratory demands. 相似文献
20.
Justin R. Eastwood Michelle L. Hall Niki Teunissen Sjouke A. Kingma Nataly Hidalgo Aranzamendi Marie Fan Michael Roast Simon Verhulst Anne Peters 《Molecular ecology》2019,28(5):1127-1137
Poor conditions during early development can initiate trade‐offs that favour current survival at the expense of somatic maintenance and subsequently, future reproduction. However, the mechanisms that link early and late life‐history are largely unknown. Recently it has been suggested that telomeres, the nucleoprotein structures at the terminal end of chromosomes, could link early‐life conditions to lifespan and fitness. In wild purple‐crowned fairy‐wrens, we combined measurements of nestling telomere length (TL) with detailed life‐history data to investigate whether early‐life TL predicts fitness prospects. Our study differs from previous studies in the completeness of our fitness estimates in a highly philopatric population. The association between TL and survival was age‐dependent with early‐life TL having a positive effect on lifespan only among individuals that survived their first year. Early‐life TL was not associated with the probability or age of gaining a breeding position. Interestingly, early‐life TL was positively related to breeding duration, contribution to population growth and lifetime reproductive success because of their association with lifespan. Thus, early‐life TL, which reflects growth, accumulated early‐life stress and inherited TL, predicted fitness in birds that reached adulthood but not noticeably among fledglings. These findings suggest that a lack of investment in somatic maintenance during development particularly affects late life performance. This study demonstrates that factors in early‐life are related to fitness prospects through lifespan, and suggests that the study of telomeres may provide insight into the underlying physiological mechanisms linking early‐ and late‐life performance and trade‐offs across a lifetime. 相似文献