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opencc-zeroDec 2018View details →

Data from: Associations between habitat quality, body size, and reproductive fitness in the alpine endemic spider Vesubia jugorum

Aim. In theory, the highest-quality habitat across a species' range should support individuals with the highest fitness, making it possible to evaluate the outputs of species distribution models (SDM) by exploring the relation between habitat quality and functional traits related to species' fitness. However, this relation has been tested almost exclusively in plants. We investigated the degree to which morphological and reproductive traits of an alpine spider varied along a gradient of habitat quality projected via species distribution models. Location. Southwestern Alps (France and Italy) Time period. 2007–2018 Major taxa studied. Vesubia jugorum (Arachnida: Araneae: Lycosidae) Methods. We used climatic, topographical and geomorphological variables at a resolution of 250 m to model habitat quality for V. jugorum, with multiple algorithms (generalized additive models, boosted regression trees, and maximum entropy models). We collected spiders in the field and measured their body size and egg-case size (a functional trait related to reproductive success). We tested the relation between functional traits and habitat quality with linear mixed models. Results. All SDM algorithms we tested fit the data well, with similar explanatory ability. Models revealed a positive relation between the probability of presence and cumulative precipitation and percentage of rock. An additional important variable in the SDMs was duration of snow coverage, with optimal projected habitat quality between 40 and 100 days/year with snow. Modeled habitat quality was positively associated with maximum body and egg-case size. Main conclusions. Our work provides evidence of a positive association between projected habitat quality and traits of a terrestrial invertebrate. A model that fits the data well potentially can be used to predict variations in species' traits, thus offering an experimental test of SDM projections with field-collected data. We encourage SDM users to incorporate data on functional traits into their modeling fitting exercises.

opencc-zeroNov 2020View details →

Fitness implications of nonlethal injuries in scorpions: females, but not males pay reproductive costs

The ability to detach a body part in response to a predation attempt is known as autotomy, and it is perhaps the most intensively studied form of nonlethal injury in animals. Although autotomy enhances survival, it may impose reproductive costs to both males and females. We experimentally investigated how autotomy affects the reproductive success of males and females of a scorpion species. Individuals of Ananteris balzani autotomize the last abdominal segments ("tail"), losing the anus and leading to lifelong constipation since regeneration does not occur. Although male "tail" is used during courtship and sperm transfer, autotomy had no effect on male mating success. The combined effect of increased mortality and reduced fecundity resulted in autotomized females producing nearly 35% less offspring than intact females. In conclusion, the negative effects of "tail" autotomy are clearly sex-dependent, probably because the factors that influence reproductive success in males and females are markedly different.

opencc-zeroJan 2021View details →

Data from: Compensatory growth in C. elegans is regulated by a thermosensitive TRP channel and increases reproductive fitness

Animals are often not growing at the maximum rate, but can compensate for a bad start of life by further increasing growth rate. While this compensatory growth is widespread, its direct fitness consequences are seldom investigated and its genetic basis is unknown. We investigated the genetic regulation, as well as fitness and lifespan consequences of compensatory growth in response to temperature, using C. elegans knockout of the thermo-sensitive TRP ion channel TRPA-1, involved in temperature recognition. We exposed juvenile worms to cold, normal or warm temperatures in order to delay or speed up development. After returning to normal temperature, we found that wild-type worms where early development was delayed, expressed compensatory growth and catched up in size, while juvenile exposure to warm temperatures expressed slowed-down growth and small size. Compensatory growth also altered the reproductive schedule towards early reproduction, so that rate-sensitive individual fitness increased even though total reproduction was unaffected. Surprisingly, no lifespan cost of compensatory growth was found. In contrast, juvenile temperature did not induce compensatory or slowed-down growth in the trpa-1 knockout mutants, and consequently did not affect fitness. We show that temperature-induced compensatory growth in C. elegans is regulated by the trpa-1 and can increase fitness.

opencc-zeroDec 2016View details →

Data from: Fitness in invasive social wasps: the role of variation in viral load, immune response and paternity in predicting nest size and reproductive output

Within any one habitat, the relative fitness of organisms in a population can vary substantially. Social insects like the common wasp are among the most successful invasive animals, but show enormous variation in nest size and other fitness-related traits. Some of this variation may be caused by pathogens such as viruses that can have serious consequences in social insects, which range from reduced productivity to colony death. Both individual immune responses and colony-level traits such as genetic diversity are likely to influence effects of pathogen infections on colony fitness. Here we investigate how infections with Kashmir Bee Virus (KBV), immune response and intracolony genetic diversity (due to queen polyandry) affect nest size in the invasive common wasp, Vespula vulgaris. We show that KBV is highly prevalent in wasps and expression of antiviral immune genes is significantly increased with higher viral loads across individuals. Patriline membership within a nest did not influence KBV susceptibility or immune response. A permutational MANCOVA revealed that polyandry, viral load, and expression of the immune gene Dicer were significant predictors of variation in nest size. High intracolony genetic diversity due to polyandry has previously been hypothesized to improve colony-level resistance to parasites and pathogens. Consistent with this hypothesis, we observed genetically diverse colonies to be significantly larger and to produce more queens, although this effect was not driven by the pathogen we investigated. Invasive wasps clearly suffer from pathogens and expend resources, as indicated here by elevated immune gene expression, toward reducing pathogen-impact on colony fitness.

opencc-zeroDec 2011View details →

Data from: Are there indirect fitness benefits of female extra-pair reproduction? Lifetime reproductive success of within-pair and extra-pair offspring

The forces driving extra-pair reproduction by socially monogamous females, and the resulting genetic polyandry, remain unclear. A testable prediction of the hypothesis that extra-pair reproduction partly reflects indirect selection on females is that extra-pair young (EPY) will be fitter than their within-pair young (WPY) maternal half-siblings. This prediction has not been comprehensively tested in a wild population, requiring data on the lifetime reproductive success (LRS) of maternal half-sib EPY and WPY. We used 17 years of genetic parentage data from song sparrows, Melospiza melodia, to compare the LRS of hatched EPY and WPY maternal half-siblings measured as their lifetime number of hatched offspring, recruited offspring and hatched grandoffspring. EPY hatchlings were not significantly fitter than WPY hatchlings for any of three measures of LRS. Furthermore, opposite to prediction, EPY hatchlings tended to have lower LRS than their maternal half-sibling WPY hatchlings on average. EPY also tended to be less likely to survive to hatch than their maternal half-sibling WPY. Taken together, these results fail to support one key hypothesis explaining the evolution of genetic polyandry by socially monogamous females and suggest there may be weak indirect selection against female extra-pair reproduction in song sparrows.

opencc-zeroDec 2018View details →

Data from: Individuals' expected genetic contributions to future generations, reproductive value, and short-term metrics of fitness in free-living song sparrows (Melospiza melodia)

Appropriately defining and enumerating 'fitness' is fundamental to explaining and predicting evolutionary dynamics. Yet, general theoretical concepts of fitness are often hard to translate into quantities that can be measured in wild populations experiencing complex environmental, demographic, genetic and selective variation. While the 'fittest' entities might be widely understood to be those that ultimately leave most descendants at some future time, such long-term legacies can rarely be measured, impeding evaluation of the degree to which tractable short-term metrics of individual fitness could potentially serve as useful direct proxies. One opportunity for conceptual and empirical convergence stems from the principle of individual reproductive value (Vi), defined as the number of copies of each of an individual's alleles that is expected to be present in future generations given the individual's realised pedigree of descendants. Since Vi tightly predicts an individual's longer-term genetic contribution, quantifying Vi provides a tractable route to quantifying what, to date, has been an abstract theoretical fitness concept. We used complete pedigree data from free-living song sparrows (Melospiza melodia) to demonstrate that individuals' expected genetic contributions stabilise within an observed 20-year (i.e. ~8 generation) time period, allowing estimation of individual Vi. Considerable among-individual variation in Vi was evident in both sexes. Standard metrics of individual lifetime fitness, comprising lifespan, lifetime reproductive success and projected growth rate, typically explained less than half the variation. We thereby elucidate the degree to which fitness metrics observed on individuals concur with measures of longer-term genetic contributions, and consider the degree to which analyses of pedigree structure could provide useful complementary insights into evolutionary outcomes.

opencc-zeroDec 2013View details →

Data from: Predators, energetics and fitness drive neonatal reproductive failure in red squirrels

Neonatal reproductive failure should occur when energetic costs of parental investment outweigh fitness benefits. However, little is known about the drivers of neonatal reproductive failure in free ranging species experiencing continuous natural variation in predator abundance and in the energetic and fitness costs and benefits associated with parental investment. Long-term comprehensive studies are required to better understand how biotic, abiotic, and life history conditions interact to drive occurrences of reproductive failure in the wild. Using 24 years (1987-2011) of reproductive data from a northern boreal population of North American red squirrels in southwestern Yukon, we examined the effects of predator abundance, energetics (resource availability, ambient temperature and litter size), and fitness benefits (probability of overwinter juvenile survival and maternal age) on occurrences of neonatal reproductive failure (494/2670 reproductive attempts; 18.5%). Neonatal reproductive failure was driven by a combination of predator abundance, and the energetic and fitness costs and benefits of parental investment. The abundance of mustelids and maternal age were positively related to the occurrence of neonatal reproductive failure. High energy costs associated with a combination of low resource availability and cold ambient temperatures or large litters, corresponded to increased occurrences of neonatal reproductive failure. However, the strength of these relationships was influenced by variation in juvenile overwinter survival (i.e. fitness benefits). We provide evidence that predation pressure is an important driver of neonatal reproductive failure. In addition, we found a trade-off occurs between resource-dependent energetic and fitness costs and benefits of raising the current litter to independence

opencc-zeroDec 2018View details →

Data from: Home ground advantage: local Atlantic salmon have higher reproductive fitness than dispersers in the wild

A long-held, but poorly tested, assumption in natural populations is that individuals that disperse into new areas for reproduction are at a disadvantage compared to individuals that reproduce in their natal habitat, underpinning the eco-evolutionary processes of local adaptation and ecological speciation. Here, we capitalize on fine-scale population structure and natural dispersal events to compare the reproductive success of local and dispersing individuals captured on the same spawning ground in four consecutive parent-offspring cohorts of wild Atlantic salmon (Salmo salar). Parentage analysis conducted on adults and juvenile fish showed that local females and males had 9.6 and 2.9 times higher reproductive success than dispersers, respectively. Our results reveal how higher reproductive success in local spawners compared to dispersers may act in natural populations to drive population divergence and promote local adaptation over microgeographic spatial scales without clear morphological differences between populations.

opencc-zeroDec 2015View details →

Data from: The effects of quantitative fecundity in the haploid stage on reproductive success and diploid fitness in the aquatic peat moss Sphagnum macrophyllum

A major question in evolutionary biology is how mating patterns affect the fitness of offspring. However, in animals and seed plants it is virtually impossible to investigate the effects of specific gamete genotypes. In bryophytes, haploid gametophytes grow via clonal propagation and produce millions of genetically identical gametes throughout a population. The main goal of this research was to test whether gamete identity has an effect on the fitness of their diploid offspring in a population of the aquatic peat moss Sphagnum macrophyllum. We observed a heavily male-biased sex ratio in gametophyte plants (ramets) and in multilocus microsatellite genotypes (genets). There was a steeper relationship between mating success (number of different haploid mates) and fecundity (number of diploid offspring) for male genets compared with female genets. At the sporophyte level, we observed a weak effect of inbreeding on offspring fitness, but no effect of brood size (number of sporophytes per maternal ramet). Instead, the identities of the haploid male and haploid female parents were significant contributors to variance in fitness of sporophyte offspring in the population. Our results suggest that intrasexual gametophyte/gamete competition may play a role in determining mating success in this population.

opencc-zeroDec 2020View details →

Data from: Inter-generational costs of oxidative stress: reduced fitness in daughters of mothers that experienced high levels of oxidative damage during reproduction

Parental condition transfer effects occur when the parents' physiological state during reproduction affects offspring performance. Oxidative damage may mediate such effects, yet evidence that oxidative damage experienced by parents during reproduction negatively affects offspring fitness is scarce and limited to early life stages. We show in Japanese quail (Coturnix japonica) that maternal levels of oxidative damage, measured during reproduction, negatively predict the number of offspring produced by daughters. This maternal effect on the daughter's reproductive success was mediated by an effect on hatching success, rather than the number of eggs laid by daughters. We also observed a negative association between the father's oxidative damage levels and the number of eggs laid by daughters, but a positive association between the father's oxidative damage levels and the hatching success of these eggs. These opposing paternal effects cancelled each other out, resulting in no overall effect on the number of offspring produced by daughters. No significant association between a female's own level of oxidative damage during reproduction and her reproductive success was observed. Our results suggest that oxidative damage experienced by parents may be a better predictor of an individual's reproductive performance than oxidative damage experienced by the individual itself. Although the mechanisms underlying these parental condition transfer effects are currently unknown, changes in egg composition or (epi-)genetic alterations of gametes may play a role. These findings highlight the importance of an inter-generational perspective when quantifying costs of physiological stress.

opencc-zeroMay 2022View details →

Extreme reproductive skew at the dawn of sociality is consistent with inclusive fitness theory but problematic for routes to eusociality

To understand the earliest stages of social evolution we need to identify species that are undergoing the initial steps into sociality. Amphylaeus morosus is the only unambiguously known social species in the bee family Colletidae and represents an independent origin of sociality within the Apoidea. This allows us to investigate the selective factors promoting the transition from solitary to social nesting. Using genome-wide SNP genotyping, we infer robust pedigree relationships to identify maternity of brood and intracolony relatedness for colonies at the end of the reproductive season. We show that A. morosus forms both matrifilial and full-sibling colonies, both involving complete or almost complete monopolization over reproduction. In social colonies, the reproductive primary was also the primary forager with the secondary female remaining in the nest, presumably as a guard. Social nesting provided significant protection against parasitism and increased brood survivorship in general. We show that secondary females gain large indirect fitness benefits from defensive outcomes, enough to satisfy the conditions of inclusive fitness theory, despite an over-production of males in social colonies. These results suggest an avenue to sociality that involves high relatedness and, very surprisingly, extreme reproductive skew in its earliest stages and raises important questions about the evolutionary steps in pathways to eusociality.

Fig. 3 in Effects of Female and Male Density on their Mating Performance and Female Post-Mating Reproductive Fitness in Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae)

Fig. 3. Effect of female and male density on female post-mating fecundity and the egg hatching rate. A–B) Female fecundity, C–D) Egg hatching rate. Different letters indicate significant differences from each other at P <0.05 (n = 29–40). The top and bottom of each box represent the upper and lower Quartiles, respectively; the horizontal line represents the median; the vertical lines extend to the minimum and maximum values within 1.5 times the inter-Quartile range.

Fig. 2 in Effects of Female and Male Density on their Mating Performance and Female Post-Mating Reproductive Fitness in Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae)

Fig. 2. Effect of female and male density on the female post-mating duration of the egg-laying period and longevity. A–B) Female longevity, C–D) Duration of egg laying. Different letters indicate significant differences from each other at P <0.05 (n = 29–40). The top and bottom of each box represent the upper and lower Quartiles, respectively; the horizontal line represents the median; the vertical lines extend to the minimum and maximum values within 1.5 times the inter-quartile range.

Fig. 1 in Effects of Female and Male Density on their Mating Performance and Female Post-Mating Reproductive Fitness in Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae)

Fig. 1. Effect of female and male density on time from pairing to successful mating and mating duration of Plagiodera versicolora. A–B) Time from pairing to successful mating, C–D) Mating duration. Different letters indicate significant differences from each other at P <0.05 (n = 30–41). The top and bottom of each box represent the upper and lower Quartiles, respectively; the horizontal line represents the median; the vertical lines extend to the minimum and maximum values within 1.5 times the inter-Quartile range.

Fig. 4 in Effects of Female and Male Density on their Mating Performance and Female Post-Mating Reproductive Fitness in Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae)

Fig. 4. Effect of female and male density on the female post-mating number of egg clutches and the number of eggs per clutch. A–B) Number of egg clutches, C–D) Number of eggs per clutch. Different letters indicate significant differences from each other at P <0.05 (n = 29–40). The top and bottom of each box represent the upper and lower Quartiles, respectively; the horizontal line represents the median; the vertical lines extend to the minimum and maximum values within 1.5 times the inter-Quartile range.

opencc-zeroJul 2022View details →

Long-term changes in occurrence, relative abundance, and reproductive fitness of bat species in relation to arrival of White-nose Syndrome in West Virginia, USA

White-nose syndrome (WNS) is a disease caused by the fungus Pseudogymnoascus destructans which has resulted in the deaths of millions of bats across eastern North America. To date, hibernacula counts have been the predominant means of tracking the spread and impact of this disease on bat populations. However, an understanding of the impacts of WNS on demographic parameters outside the winter season is critical to conservation and recovery of bat populations impacted by this disease. We used long-term monitoring data to examine WNS-related impacts to summer populations in West Virginia, where WNS has been documented since 2009. Using capture data from 290 mist-net sites surveyed from 2003–2019 on the Monongahela National Forest, we estimated temporal patterns in presence and relative abundance for each bat species. For species that exhibited a population-level response to WNS, we investigated post-WNS changes in adult female reproductive state and body mass. Myotis lucifugus (little brown bat), M. septentrionalis (northern long-eared bat), and Perimyotis subflavus (tri-colored bat) all showed significant decreases in presence and relative abundance during and following the introduction of WNS, while Eptesicus fuscus (big brown bat) and Lasiurus borealis (eastern red bat) responded positively during the WNS invasion. Probability of being reproductively active was not significantly different for any species, though a shift to earlier reproduction was estimated for E. fuscus and M. septentrionalis. For some species, body mass appeared to be influenced by the WNS invasion, but the response differed by species and reproductive state. Results suggest that continued long-term monitoring studies, additional research into impacts of this disease on the fitness of WNS survivors, and a focus on providing optimal non-wintering habitat may be valuable strategies for assessing and promoting recovery of WNS-affected bat populations.

opencc-zeroSep 2021View details →

Context dependent fitness costs of reproduction despite stable body mass costs in an Arctic herbivore

1. The cost of reproduction on demographic rates is often assumed to operate through changing body condition. Several studies have found that reproduction depresses body mass more if the current conditions are severe, such as high population densities or adverse weather, than under benign environmental conditions. However, few studies have investigated the association between the fitness and body mass costs of reproduction. 2. Using 25 years of individual-based capture-recapture data from Svalbard reindeer (Rangifer tarandus platyrhynchus), we built a novel Bayesian state-space model that jointly estimated inter-annual change in mass, annual reproductive success, and survival, while accounting for incomplete observations. The model allowed us to partition the differential effects of intrinsic and extrinsic factors on both non-reproductive mass change and the body mass cost of reproduction and to quantify their consequences on demographic rates. 3. Contrary to our expectation, the body mass cost of reproduction (mean = 5.8 kg) varied little between years (CV = 0.08) whereas the between-year variation in body mass changes, that were independent of the previous year's reproductive state, varied substantially (CV = 0.4) in relation to autumn temperature and the amount of rain-on-snow in winter. This mass loss led to a cost of reproduction on the next reproduction, which was amplified by the same environmental covariates, from a 10% reduction in reproductive success in benign years, to a 50% reduction in harsh years. The reproductive mass loss also resulted in a small reduction in survival. 4. Our results show how demographic costs of reproduction, driven by inter-annual fluctuations in individual body condition, result from the balance between body mass costs of reproduction and body mass changes that are independent of previous reproductive state. We illustrate how a strong context dependent fitness cost of reproduction can occur, despite a relatively fixed body mass cost of reproduction. This suggests that female reindeer display a very conservative energy allocation strategy, either aborting their reproductive attempt at an early stage or weaning at a relatively constant cost. Such a strategy might be common in species living in a highly stochastic food limited environment.

opencc-zeroJul 2023View details →

Data for: Lack of intergenerational reproductive conflict, rather than lack of inclusive fitness benefits, likely explains absence of post-reproductive lifespan in long-finned pilot whales

Life history theory suggests that individuals should reproduce until death, yet females of a small number of mammals live for a significant period after ceasing reproduction, a phenomenon known as post-reproductive lifespan. It is thought that the evolution of this trait is facilitated by increasing local relatedness throughout a female's lifetime. This allows older females to gain inclusive fitness through helping their offspring (known as a mother effect) and/or grandoffspring (known as a grandmother effect), rather than gaining direct fitness through reproducing. However, older females may only benefit from stopping reproducing when their direct offspring compete with those of their daughters. Here, we investigate whether a lack of post-reproductive lifespan in long-finned pilot whales (Globicephala melas) results from minimal benefits incurred from the presence of older females, or from a lack of costs resulting from mother-daughter co-reproduction. Using microsatellite data, we conducted parentage analysis on individuals from 25 pods and find that younger females were more likely to have offspring if their mother was present in their pod, indicating that mothers may assist inexperienced daughters to reproduce. However, we found no evidence of reproductive conflict between co-reproducing mothers and daughters, indicating that females may be able to reproduce into old age whilst simultaneously aiding their daughters in reproduction. This highlights the importance of reproductive conflict in the evolution of a post-reproductive lifespan and demonstrates that mother and grandmother effects alone do not result in the evolution of a post-reproductive lifespan.