Explore the vast range of titles available.

Oviposition-site choice is a major maternal effect by which females can affect the survival and phenotype of their offspring. Across oviparous species, the ultimate reasons for females' selection of oviposition sites often differ. We present six hypotheses that have been used to explain nonrandom oviposition-site choice in insects, fish, amphibians, reptiles, and birds: ( a ) maximizing embryo survival, ( b ) maximizing maternal survival, ( c ) modifying offspring phenotype, ( d ) proximity to suitable habitat for offspring, ( e ) maintaining natal philopatry, and ( f ) indirect oviposition-site choice via mate choice. Because these hypotheses differ in their relevance across oviparous taxa, each hypothesis must be tested to ensure accurate understanding of the ultimate reason behind oviposition-site choice in a particular taxon. By presenting the major hypotheses for oviposition-site choice as they relate to diverse oviparous animals, we nonetheless illustrate particular trends across animal taxa, while highlighting avenues for future research into the ecological and evolutionary drivers of oviposition-site choice.

Understanding the evolution of life histories requires information on how life histories vary among individuals and how such variation predicts individual fitness. Using complete life histories for females in a well-studied population of wild baboons, we tested two nonexclusive hypotheses about the relationships among survival, reproduction, and fitness: the quality hypothesis, which predicts positive correlations between life-history traits, mediated by variation in resource acquisition, and the trade-off hypothesis, which predicts negative correlations between life-history traits, mediated by trade-offs in resource allocation. In support of the quality hypothesis, we found that females with higher rates of offspring survival were themselves better at surviving. Further, after statistically controlling for variation in female quality, we found evidence for two types of trade-offs: females who produced surviving offspring at a slower rate had longer life spans than those who produced surviving offspring at a faster rate, and females who produced surviving offspring at a slower rate had a higher overall proportion of offspring survive infancy than females who produced surviving offspring at a faster rate. Importantly, these trade-offs were evident even when accounting for (i) the influence of offspring survival on maternal birth rate, (ii) the dependence of offspring survival on maternal survival, and (iii) potential age-related changes in birth rate and/or offspring survival. Our results shed light on why trade-offs are evident in some populations while variation in individual quality masks trade-offs in others.

Animals that reproduce in temporary aquatic systems expose their offspring to a heightened risk of desiccation, as they must race to complete development and escape before water levels recede. Adults must therefore synchronise reproduction with the changing availability of water, yet the conditions they experience to trigger such an event may not relate to those offspring face throughout development, potentially leading to clutch failure. The sandpaper frog (Lechriodus fletcheri) breeds in ephemeral pools that dry within days to weeks after rainfall has ceased. We examined whether spawning frequency and offspring survival differed across two consecutive breeding seasons based on (1) rainfall at the moment of oviposition and throughout offspring development, and (2) pool volume, given their combined effect on hydroperiod. Reproduction was triggered by rainfall, with more spawn laid during periods of greater rainfall and in larger pools. While pool size was a predictor of offspring survival, rainfall during oviposition was not. Rather, follow-up rain events were required to prevent pools drying prior to metamorphosis, with rainfall evenness during development the strongest predictor of reproductive success. High clutch failure rates recorded in both seasons suggest that adults do not have the capability to predict rainfall frequency post-oviposition. We thus conclude that unpredictable rainfall leading to premature desiccation of spawning sites is the primary source of pre-metamorphic mortality for this species. Understanding the influence of rainfall predictability on offspring survival could be critical in predicting the effects of altered hydroperiod regimes due to climate change for species that exploit temporary waters.

Offspring are often produced in excess as insurance against stochastic events or unpredictable resources. This strategy may result in high early-life mortality, yet age-specific mortality before offspring independence and its associated costs have rarely been quantified. In this study, we modelled age-specific survival from hatching to fledging using 24 years of data on hatching order (HO), growth and age of mortality of more than 15 000 common tern (Sterna hirundo) chicks. We found that mortality peaked directly after hatching, after which it declined rapidly. Mortality hazard was best described with the Gompertz function, and was higher with later HO, mainly due to differences in baseline mortality hazard, rather than age-dependent mortality. Based on allometric mass–metabolism relationships and detailed growth curves of starving chicks, we estimated that the average metabolizable energy intake of non-fledged chicks was only 8.7% of the metabolizable energy intake of successful chicks during the nestling phase. Although 54% of hatchlings did not fledge, our estimates suggest them to have consumed only 9.3% of the total energy consumption of all hatched chicks in the population before fledging. We suggest that rapid mortality of excess offspring is part of an adaptive brood reduction strategy to the benefit of the parents.

Male senescence has detrimental effects on reproductive success and offspring fitness. When females mate with multiple males during the same reproductive bout, post-copulatory sexual selection that operates either through sperm competition or cryptic female choice might allow females to skew fertilization success towards young males and as such limit the fitness costs incurred when eggs are fertilized by senescing males. Here, we experimentally tested this hypothesis. We artificially inseminated female North African houbara bustards with sperm from dyads of males of different (young and old) or similar ages (either young or old). Then, we assessed whether siring success was biased towards young males and we measured several life-history traits of the progeny to evaluate the fitness costs due to advanced paternal age. In agreement with the prediction, we found that siring success was biased towards young males, and offspring sired by old males had impaired hatching success, growth and post-release survival (in females). Overall, our results support the hypothesis that post-copulatory sexual selection might represent an effective mechanism allowing females to avoid the fitness costs of fertilization by senescing partners.

Fine-scale monitoring of neonate mammals can provide important data about survival rates and cause-specific mortality. However, the VHF transmitters and collars frequently used to monitor neonate mammals necessitate logistically intensive field efforts, often requiring personnel to check on collared animals several times a day. We adapted technology that creates a proximity link between GPS collars fitted on adult animals to expandable VHF collars fitted for use on neonate cougar kittens (Puma concolor). We describe and evaluate the use of this system, which resulted in an 87% success rate of tracking kittens from ~5 weeks to 6 months of age. Our experience with these collars suggests that this technology can be used to enhance understanding of neonate survival and to gain information about maternal behavior and time allocation with offspring, providing a new source of data that was previously unobservable.

Abstract Chromosomal inversions have long been appreciated as an important source of genetic diversity, local adaptation, and speciation. However, selection pressures maintaining ancestral and derived alleles at high frequency over extended periods of time remain poorly characterized. Using genome-wide single-nucleotide polymorphism markers and shared barcodes of linked-read sequences from 20 wild and 7 captive zebra finches Taeniopygia guttata, we systematically scanned a high-quality zebra finch reference genome and identified all large polymorphic inversions that segregate at high minor allele frequencies. Apart from the known polymorphic inversions on chromosomes Tgu5, Tug11, Tgu13, and TguZ, we characterized two inversions on microchromosomes Tgu26 and Tgu27 and identified another eight putative inversions, located mostly on microchromosomes and ranging in size from 0.42 to 65.22 Mb. Population genomic analyses show that most of the six bona fide inversions are complex, containing short nested inversions. The early inversions emerged an estimated 0.6 to 2.2 million years ago and segregate at relatively high frequencies in the wild (minor haplotype frequency range: 0.289 to 0.429). Based on fitness-related measures of about 5,000 captive zebra finches, we conclude that three of the inversion polymorphisms (Tgu11, Tgu27, and TguZ) may be maintained by net heterosis. In the youngest of the six inversions (Tgu13), the derived haplotype showed weak positive additive effects on various fitness components. In combination with previous discoveries, we provide a comprehensive overview of the genomic distribution and evolutionary dynamics of large polymorphic inversions in the panmictic zebra finch. Our findings highlight (i) that microchromosomes may harbor quite a few additional inversion polymorphisms, (ii) that most of the inversions contain smaller nested or overlapping inversions, and (iii) that inversions were most likely maintained by weak heterosis with small fitness effects requiring large sample sizes to be detected.

Female mate choice is usually based on traits that signal male quality as a sexual partner. According to the “good parent” hypothesis, female mate choice may also consider male quality as a caregiver in species with male-only care. Because parental activities may be costly, males in good condition should be more attractive to females than those in poor condition. We experimentally manipulated the body condition of non-parental and parental males of the egg-tending harvestman Iporangaia pustulosa and then evaluated how it affected their mating success and ability to protect eggs under field conditions. For non-parental males, individuals in good condition had twice the probability of mating than those in poor condition. For parental males, individuals in good condition had two times more chances of mating and acquired five times more eggs than those in poor condition. Surprisingly, males’ body condition had no effect on the efficiency of egg protection. Although our results indicate that the male condition is a sexually selected trait, we found no support for the “good parent hypothesis” given that an increase in body condition does not improve the survival of the offspring under male care. Instead, these findings are congruent with predictions of the “essential male care” model, which suggests that, when the costs of parental care are low (as is the case of egg attendance), most males can provide the minimum necessary care for offspring survival. However, only males in good condition can allocate surplus energy to advertise their overall quality and attract more mates.Significance statementStudies examining female mate choice based on condition-dependent traits that serve as reliable indicators of male caregiving quality are mostly limited to vertebrates. We present one of the first empirical examples demonstrating that male body condition influences male attractiveness in an arthropod species exhibiting male-only care. Our field-based results show that females prefer males, whether non-parental or parental, in good body condition over those in poor condition. However, we found no evidence that an increase in body condition improves the survival of the offspring under male care. We propose that males in good body condition are more attractive because the relatively low costs of egg attendance allow them to allocate their surplus energy into advertising their overall quality. Our findings are congruent with predictions of the “essential male care” model, which explores resource allocation between paternal care and sexual advertising.

Aim The life history of a species is determined by trade-offs between growth, survival and reproduction to maximize fitness in a given environment. Following a theoretical model, we investigate whether the composition of marine fish communities can be understood in terms of a set of life-history strategies and whether the prevalence of the strategies follows specific spatial patterns that can be related to the environment. Location European seas. Time period 1980-2014. Major taxa studied Fish. Methods An extensive set of scientific bottom trawl surveys was collected to obtain the species composition of fish communities across European seas. We complemented these data with species-specific information regarding six life-history traits, reflecting reproductive, growth and feeding modes. We then calculated the optimal number of strategies needed to summarize the information contained in the traits by using archetypal analysis. The proportion of each obtained strategy in the communities and their spatial patterns were explained as a function of the environment and their temporal changes were investigated. Results The species could be decomposed into a continuum of three life-history strategies—opportunistic, periodic and equilibrium—resulting from trade-offs between traits. The marked spatial patterns of these strategies could be explained by depth, temperature and its seasonality, chlorophyll and fishing effort. In recent years, opportunistic and equilibrium strategies significantly increased, probably due to an increase in temperature and decrease in fishing effort. Main conclusions Our empirical analysis supports a theoretical framework outlining three life-history strategies of fish. The strategies vary predictably in space and time in response to the environment. This highlights the underlying process whereby fitness is optimized through trade-offs between growth, feeding and reproduction under different environmental conditions. Due to their response to the environment, life-history strategies provide a suitable tool for monitoring and understanding community changes in response to natural and anthropogenic stressors, including fishing and climate change.

Seventy‐five years ago, Lack proposed that there should be an optimal clutch size shared by all individuals in a population and favored by natural selection, which maximizes the number of recruited offspring. While some studies support this “common optimum” hypothesis, others have shown that the optimal clutch size depends on maternal state (e.g., age and body condition, “state‐dependent optimization”). These contrasting results suggest that the degree of state dependency might itself depend on the ecological context (e.g., capital vs. income breeding). Furthermore, almost all these studies were conducted on fast‐living species and have ignored interdependencies among variables such as maternal age and condition. Here, we test whether females share a common optimal litter size or have a state‐dependent optimal litter size in a slow‐paced capital breeder, the polar bear (Ursus maritimus). To do so, we assess the influences of (1) maternal state on litter size, (2) maternal state and litter size on cub mass, and (3) maternal state, litter size, and cub mass on cub survival, using path analysis to account for interdependencies among variables and capture–recapture modeling to estimate cub survival. We use 34 years (1992–2025) of individual‐based data from a polar bear subpopulation in the Svalbard region of Norway. In accordance with the state‐dependent optimization hypothesis, litter size varied with maternal age and size. Middle‐aged and sized females had the highest probability of having twins. Old and large females more often had triplet litters. Cub mass decreased with increasing litter size, whereas litter mass increased, meaning females with a large litter allocated more resources to reproduction. Cub mass in turn strongly predicted cub survival, indicating that offspring survival was traded against offspring number. In middle‐aged and old females, productivity—the number of cubs surviving their first year—increased with litter size, in accordance with the state‐dependent optimization hypothesis. Overall, our results are consistent with a state‐dependent optimization of litter size in this large, slow‐paced mammal producing small litters. State dependence of litter size may be more likely in capital breeders as the amount of energy available for reproduction is known in advance.