Search

Animal nests provide a beneficial environment for offspring development and as such, contribute to fitness. Gathering and transporting materials to construct nests is energetically costly, but the life history trade-offs associated with the types of nests built are largely unknown. Who contributes to building the nest could also mediate these trade-offs, as building a nest as a couple is expected to be less costly per individual than building alone. Using a comparative analysis of 227 songbird species globally, we found a fecundity cost associated with the type of nest a species builds. Species that build domed nests produce fewer broods per year than species building cups or platforms. Dome nesting species also have larger clutch sizes than open nesting species, but only when the nest is built by a couple and not when females build nests alone. This suggests that building domed nests represents a trade-off with investment in young, especially when females are solely responsible for nest building. More broadly, our results could explain macroevolutionary patterns, such as the recent finding that females, building on their own, more often build open cups rather than domed nests. [ABSTRACT FROM AUTHOR]

Plant biomass allocation is mainly affected by the environment where each individual grows. In this sense, through the rapid global expansion of impermeable areas, urbanization has strong, albeit poorly understood, consequences on the biomass allocation of plants found in this environment. Nevertheless, the comprehension of biomass allocation processes in urban shrubs remains unclear, because most studies of urban ecology focus on tree species. This is an important gap of knowledge because a great part of urban vegetation is composed of shrubs and their association with trees have positive impacts in urban ecosystem services. In this study, we explored the ecological and potential selective pressure effects of an urbanization gradient on the biomass allocation patterns of aboveground organs of Turnera subulata, a widely distributed tropical shrub. We have demonstrated that, for certain reproductive organs, biomass allocation decreases in locations with higher urbanization. Unlike expected, the biomass of vegetative organs was not affected by urbanization, and we did not observe any effect of urbanization intensity on the variance in biomass allocation to vegetative and reproductive organs. We did not record urbanization-mediated trade-offs in biomass allocation for reproductive and vegetative organs. Instead, the biomass of these structures showed a positive relationship. Our data suggest that urbanization does not result in radical changes in biomass allocation of T. subulata, and neither in the variation of these traits. They indicate that the ability of T. subulata to thrive in urban environments may be associated with life history and morphological mechanisms. Our findings contribute to the understanding of shrub plant responses to urbanization and highlight urbanization as a potential factor in resource allocation differences for different structures and functions in plants living in these environments. [ABSTRACT FROM AUTHOR]

Juvenile diet can profoundly affect subsequent adult development, morphology and reproductive investment. Yet, little is known about how juvenile diet affects adult investment into chemical‐based sexual signalling, perhaps due to the historical assumption that pheromone production is not costly. We explored how juvenile diet influenced the reproductive investment of adults in the gumleaf skeletonizer moth, Uraba lugens. Juveniles were reared on different host plant species (Eucalyptus camaldulensis and Eucalyptus moorei) and on E. moorei host plants with different fertilizer treatments (fertilized and non‐fertilized). These juvenile diets differ in foliage carbon and nitrogen content. Several adult life history traits were influenced by juvenile diet, including body size in females, and longevity in males. However, we found no evidence from Y‐maze olfactometer assays that diet affected the attractiveness of female pheromones to males. Finally, host plant species affected male pre‐copulatory investment: males reared on E. moorei had longer antennae, but less dense sensilla. Combined, our experiments suggest that the effects of juvenile diet on investment in reproductive traits, including those associated with signalling, differ between males and females. Females allocate nutrients to adult body size, which determines fecundity. In contrast, males allocate nutrients to adult longevity and antennae size, both of which improve mate search and mating success. [ABSTRACT FROM AUTHOR]

Abstract Reproductive investment decision is an integral part of life-history theory. Differential allocation hypothesis predicts that females should increase investment when mated to high-quality males, conversely, reproductive compensation hypothesis predicts that females should increase investment when mated to low-quality males. Empirical research dominantly focuses on polygamous species and rarely on serially monogamous species. So, the question remains: which hypothesis does serially monogamous species fit? And if it fits reproductive compensation hypothesis, do females only compensate once or continuously for multiple times when mating to low-quality males? Here, we used a serially monogamous fish, the lined seahorse (Hippocampus erectus), to investigate the reproductive investment pattern of females in relation to male quality (measured by sexual attractiveness). We found that females allocated more resources into eggs when they mated to less-sexually-attractive males, indicating the investment pattern of lined seahorse falls in with the prediction of reproductive compensation hypothesis. This finding may imply that the sex role of seahorses is reversed, and female is the side imposed on a greater sexual selection pressure. On this basis, we compared the investment difference of females in two consecutive breeding events when mated to less-sexually-attractive males. We found that females allocated less resources into eggs in the second breeding than in the first one. Females reduced their reproductive compensation in the second breeding, which may be attributed to the improvement in the quality (e.g., paternal care ability) of their mates after the first breeding, thus eliminating the need for them to invest more in the second breeding.

Heavy metal pollution is known to negatively affect numerous traits in birds, including foraging, metabolism, immunity, and reproductive success. In this study, our primary aim was to assess the impact of metal pollution exposure on the visual appearance of the pied flycatcher Ficedula hypoleuca eggs. Specifically, we focused on blue‐green biliverdin‐based coloration, a trait expected to function as a signal of female quality to males. In line with the sexually selected egg coloration (SSEC) hypothesis, which posits that males respond to more intensely colored eggs by increasing their provisioning effort, our second objective was to investigate whether metal pollution exposure affects this specific signaling mechanism and subsequent male behavior. Our results showed that although coloration did not correlate with female quality or male provisioning effort, egg blue‐green coloration decreased in polluted areas compared to non‐polluted control areas. Our analysis of reflectance data revealed that this difference was due to an increased ultraviolet reflectance of eggs from polluted areas, likely caused by changes in eggshell microstructure (e.g. porosity). We therefore propose that metal pollution exposure may compromise crucial color signals of bird eggs. Avian visual modeling indicated that eggs laid by different flycatcher females are generally very similar, making discrimination by males challenging and perhaps impossible especially in dark cavities. Overall, our results suggest that the SSEC hypothesis may lack adaptive relevance for the pied flycatcher in northern Europe, even in environments influenced by anthropogenic activities. [ABSTRACT FROM AUTHOR]

In iteroparous animals, it may be adaptive to adjust the amount of reproductive investment based on their current competitive ability. Male fiddler crabs use an enlarged major claw for claw-waving display in the breeding season. Males sometimes lose their claws, but they can regenerate a claw, which is an inferior weapon for male-male fights. Here, we compared the waving frequency between males with a regenerated claw (regenerated males) and with an original claw (original males) to examine the differences in the amount of reproductive investment. Regenerated males showed lower waving frequency than original males, but some regenerate males waved frequently before the optimal mating season where original males waved frequently. These results indicate that individuals with poor fighting ability that have lower chance of acquiring females invested less in waving, and may also have shifted their peak of mating period in order to avoid competition with original males. [ABSTRACT FROM AUTHOR]

Reproductive allocation and cost play a crucial role in the survival of organisms, but research on these traits in bryophytes has been limited and inconsistent. To address this, we conducted a literature review focusing on bryophyte studies. Our goal was to clarify inconsistencies and explore reproductive allocation and cost concepts, as well as current trends in bryophyte reproduction. We examined different approaches and highlighted advantages and limitations. We emphasized five key topics: the importance of understanding reproductive allocation and reproductive cost in bryophytes; the significance of bryophytes as model organisms; historical research; terminological and methodological inconsistencies; sexual dimorphism and reproductive allocation; and measurement methods. Furthermore, we provided insights into future perspectives. Based on our findings, we advocate for standardized quantification of reproductive allocation. Standardization would enhance comparability and synthesis of results, ultimately advancing our understanding of reproductive allocation and cost of reproduction in bryophytes. [ABSTRACT FROM AUTHOR]

Amniotes differ substantially in absolute and relative brain size after controlling for allometry, and numerous hypotheses have been proposed to explain brain size evolution. Brain size is thought to correlate with processing capacity and the brain's ability to support complex manipulation such as nest‐building skills. The increased complexity of nest structure is supposed to be a measure of an ability to manipulate nesting material into the required shape. The degree of nest‐structure complexity is also supposed to be associated with body mass, partly because small species lose heat faster and delicate and insulated nests are more crucial for temperature control of eggs during incubation by small birds. Here, we conducted comparative analyses to test these hypotheses by investigating whether the complexity of species‐typical nest structure can be explained by brain size and body mass (a covariate also to control for allometric effects on brain size) across 1353 bird species from 147 families. Consistent with these hypotheses, our results revealed that avian brain size increases as the complexity of the nest structure increases after controlling for a significant effect of body size, and also that a negative relationship exists between nest complexity and body mass. [ABSTRACT FROM AUTHOR]

Metabolic rates are linked to key life-history traits that are thought to set the pace of life and affect fitness, yet the role that parents may have in shaping the metabolism of their offspring to enhance survival remains unclear. Here, we investigated the effect of temperature (24°C or 30°C) and feeding frequency experienced by parent zebrafish (Danio rerio) on offspring phenotypes and early survival at different developmental temperatures (24°C or 30°C). We found that embryo size was larger, but survival lower, in offspring from the parental low food treatment. Parents exposed to the warmer temperature and lower food treatment also produced offspring with lower standard metabolic rates—aligning with selection on embryo metabolic rates. Lower metabolic rates were correlated with reduced developmental and growth rates, suggesting selection for a slow pace of life. Our results show that intergenerational phenotypic plasticity on offspring size and metabolic rate can be adaptive when parent and offspring temperatures are matched: the direction of selection on embryo size and metabolism aligned with intergenerational plasticity towards lower metabolism at higher temperatures, particularly in offspring from low-condition parents. These findings provide evidence for adaptive parental effects, but only when parental and offspring environments match. This article is part of the theme issue 'The evolutionary significance of variation in metabolic rates'. [ABSTRACT FROM AUTHOR]

Although coastal ecosystems are naturally submitted to temporal variations of salinity, salinization has been increasing over time threatening coastal biodiversity. Species that exploit such habitats can thus be exposed to brackish water at different life stages. However, the impacts of variations of salinity on wildlife remain poorly understood. This is particularly true for coastal amphibians, due to the strong dependency of early life stages (embryos and larvae) on aquatic environments. In order to investigate the effect of salinity during egg laying and embryonic and larval development of coastal amphibians, we used a full-factorial design to expose reproductive adults, eggs, and larvae of coastal spined toads (Bufo spinosus) to fresh (0 g.l−1) or brackish water (4 g.l−1). At egg laying, we evaluated parental investment in reproduction. During embryonic and larval development, we assessed effects on survival, development, and growth. We highlighted strong effects of environmental salinity on reproduction (reduced egg laying time, marginally reduced egg size, and reduced investment in reproduction). Responses to salinity were highly dependent on the developmental stages of exposure (stronger effects when individuals were exposed during embryonic development). These effects carried over when exposure occurred at egg laying or during embryonic development, highlighting the importance of the environmental conditions during early life on ontogenetic trajectories. We also highlighted partial compensation when individuals were transferred back to freshwater. Whether the magnitude of these responses can allow coastal biodiversity to overcome the observed detrimental effects of salinization remain to be assessed. [ABSTRACT FROM AUTHOR]

Perceived predation risk alters prey behaviour and physiology, but few studies have examined downstream consequences on prey demography in wild populations. Perceived predation risk could alter adult reproductive performance via reduced investment in offspring quality and post-birth care. We manipulated perceived predation risk in snowshoe hare (Lepus americanus Erxleben, 1777) by exposing pregnant mothers to chases by a domestic dog (Canis familiaris Linnaeus, 1758). Litter size was comparable between risk-augmented and control groups, but treated females had more stillbirths and gave birth to leverets of lower body condition. Leverets from risk-augmented females had 88% higher 40-day mortality rate. Maternally preventable causes of death like starvation or predation by red squirrel (Tamiasciurus hudsonicus (Erxleben, 1777)) caused this difference, particularly during the nursing period. Risk-augmented mothers were always more active than controls, but the difference was greatest during the nursing period. We found that perceived predation risk reduces maternal productivity pre- and post-partum, implying downstream consequences to populations. Because our treatment ended before parturition, we can link offspring performance such as survival and behaviour specifically to maternal life-history trade-offs, which has not been shown in a wild mammal. [ABSTRACT FROM AUTHOR]

Female reproductive effort is defined as the proportion of total energy or resources devoted to reproduction. In reptiles, there is frequently high inter- and intra-population variation related to several factors, such as food availability, climatic conditions, age and size, all of which, in turn, also influence survival and future reproduction. The present study is the first reproductive effort analysis of a population of the high-mountain scincid lizard Plestiodon copei in central Mexico, focusing on relative litter mass (RLM), investment per capita (INV) and productivity (PROD). We also compared the reproductive efficacy of P. copei to those of other Mexican congeners. We collected 24 gravid females of P. copei over a 4-year period and recorded a total of 90 neonates born in captivity. We found significant variation in neonatal mass amongst individual females and across years. We recorded an average litter size of 3.75 and an average litter mass of 1.25 g, which were positively correlated with both the size and total mass of the reproductive females. The RLM , INV and PROD values (0.301, 0.428 g and 1.236 g × year-1, respectively) for P. copei were greater than those for other Mexican species in the P. brevirostris group (0.290, 0.412 g and 1.135 g × year-1), revealing that females of P. copei from Tenango invest a comparatively high amount of their resources in reproduction. [ABSTRACT FROM AUTHOR]

Seasonal animal dormancy is widely interpreted as a physiological response for surviving energetic challenges during the harshest times of the year (the physiological constraint hypothesis). However, there are other mutually non-exclusive hypotheses to explain the timing of animal dormancy, that is, entry into and emergence from hibernation (i.e. dormancy phenology). Survival advantages of dormancy that have been proposed are reduced risks of predation and competition (the ‘life-history’ hypothesis), but comparative tests across animal species are few. Using the phylogenetic comparative method applied to more than 20 hibernating mammalian species, we found support for both hypotheses as explanations for the phenology of dormancy. In accordance with the life-history hypotheses, sex differences in hibernation emergence and immergence were favored by the sex difference in reproductive effort. In addition, physiological constraint may influence the trade-off between survival and reproduction such that low temperatures and precipitation, as well as smaller body mass, influence sex differences in phenology. We also compiled initial evidence that ectotherm dormancy may be (1) less temperature dependent than previously thought and (2) associated with trade-offs consistent with the life-history hypothesis. Thus, dormancy during non-life-threatening periods that are unfavorable for reproduction may be more widespread than previously thought.

The Argentinean shortfin squid, Illex argentinus, is an oceanic cephalopod displaying characteristics of short lifespan, fast growth rate, and semelparous reproduction. Here, we aimed to comprehensively understand the squidxs life history strategy by investigating the body condition and gonadosomatic index of mature male squids collected from the high seas of the southwest Atlantic Ocean during the 2018-2021 fishing season. Our evaluations used residual index analysis and mixed-effects models to evaluate the relationships between body condition and gonadosomatic index and the key oceanic variables, including sea surface temperature (SST) and chlorophyll a concentration (Chla). The application of the mixed-effects models allowed us to explore the potential influences of habitat environment on somatic and reproductive growth. Our results showed that mature male I. argentinus had a measured mantle length (ML) between 143 mm and 291 mm and a body weight between 89 g and 559 g. We also noted that the largest individuals were collected in 2020, whereas the smallest were collected in 2018. The b values for individuals from 2018 to 2020, estimated using a power regression of body weight versus mantle length, were significantly different from the assumed isometric growth coefficient b value (equals to 3). The standardized residuals of BW-ML relationships indicated that the individuals collected in 2020 retained the best body condition, whereas the individuals from 2018 to 2021 displayed poor body condition. In contrast, mature male I. argentinus showed the lowest gonadosomatic index in 2020, followed by 2018 and 2021. Mixed-effects model evaluations revealed a significant correlation between body condition, SST, and Chla. The individuals displayed a decreasing trend in body condition in response to increasing sea surface temperature, from 9.0 ℃ to 12.5 ℃, and body conditions improved when the chlorophyll a concentration was around 1 mg/m3. Mixed-effects modeling also revealed that the gonadosomatic index was positively correlated with SST, demonstrating a relatively high value at approximately 15 ℃. Taken together, these findings indicate that there is a trade-off between body condition and reproductive investment, and that SST has a significant influence on body condition and reproductive investment for mature male I. argentinus. Additionally, chlorophyll a concentration also demonstrated a significant influence on the body condition of mature male I. argentines.

Life‐history theory suggests that ageing is one of the costs of reproduction. Accordingly, a higher reproductive allocation is expected to increase the deterioration of both the somatic and the germinal lines through enhanced telomere attrition. In most species, males' reproductive allocation mainly regards traits that increase mating and fertilization success, that is sexually selected traits. In this study, we tested the hypothesis that a higher investment in sexually selected traits is associated with a reduced relative telomere length (RTL) in the guppy (Poecilia reticulata), an ectotherm species characterized by strong pre‐ and postcopulatory sexual selection. We first measured telomere length in both the soma and the sperm over guppies' lifespan to see whether there was any variation in telomere length associated with age. Second, we investigated whether a greater investment in pre‐ and postcopulatory sexually selected traits is linked to shorter telomere length in both the somatic and the sperm germinal lines, and in young and old males. We found that telomeres lengthened with age in the somatic tissue, but there was no age‐dependent variation in telomere length in the sperm cells. Telomere length in guppies was significantly and negatively correlated with sperm production in both tissues and life stages considered in this study. Our findings indicate that telomere length in male guppies is strongly associated with their reproductive investment (sperm production), suggesting that a trade‐off between reproduction and maintenance is occurring at each stage of males' life in this species. [ABSTRACT FROM AUTHOR]

Cooperation between kin and cooperation between non-kin often appear functionally similar, but the evolutionary mechanisms that drive the emergence of these two forms of cooperation can be dramatically different. The mechanisms responsible for non-kin cooperation, in particular, are not well established in an empirical context. To truly understand the emergence of non-kin cooperation, the fitness outcomes of cooperation should be compared with the alternate strategy of solitary living in the same environment. Ant populations that contain a mix of queens who found nests alone (monogyny), and cooperative unrelated ant queens who found nests together and remain together through colony development (primary polygyny), provide a useful natural context to make such a comparison. To estimate the reproductive costs for primary polygyny relative to solitary nest founding, we measured alate (reproductive) production for colonies in a mixed population of polygynous and monogynous California harvester ant colonies over a 2-year period. Colony-level reproductive output was not substantially higher in polygynous colonies compared to those with single queens, and consequent per-queen reproductive gain was significantly lower. Given that polygynous queens in this population are unrelated, nest sharing thus generates a significant annual and potentially lifetime cost for cooperative queens. Comparative measures of colony dynamics, however, suggest that polygynous colonies have a larger or more active workforce than monogynous colonies. Additionally, polygynous colonies may be more conservative than monogynous colonies in resource allocation towards reproduction. These results collectively suggest that primary polygyny generates annual reproductive fitness costs. However, polygynous colonies likely also shift life history strategies in ways that emphasize long-term survival and colony growth over immediate reproduction. Over time, this shift may mitigate the annual fitness costs of cooperation. Significance statement: When things get difficult, it pays to work together. In some ant species, unrelated queens form long-term cooperative associations that share resources and a workforce within a single nest. The fitness consequences and evolutionary drivers of non-kin cooperation in this and other systems are unclear. We compared the reproductive investment and colony dynamics of single-queen and multi-queen California harvester ant colonies in a shared environment to directly compare the fitness of cooperative and non-cooperative queens. Our data suggest that cooperation not only lowers annual per-queen reproduction, but also produces a more robust colony that may recoup annual fitness losses by extending colony longevity. [ABSTRACT FROM AUTHOR]

I examined sex allocation of offspring in northern flickers, Colaptes auratus , a woodpecker with biparental care and sexual size dimorphism. The analysis of data involving 8321 nestlings that were sexed over a span of 16 years revealed no significant bias towards the smaller sex (females) at the population level (all fledglings pooled), counter to the Fisherian hypothesis of equal investment at the end of parental care. At the level of the brood, high-quality parents (older and in better body condition) did not produce more of the expensive sex (males) counter to the Trivers–Willard hypothesis. Brood sex ratios were somewhat repeatable among females but did not vary significantly with year, clutch size or hatching date probably because the main food of flickers, ground-dwelling ants, is relatively invariable. Mother flickers allocated more of the cheaper sex to last-hatched offspring in asynchronous broods, consistent with the 'intrabrood sharing-out hypothesis' but not the 'competitive advantage hypothesis'. The female-bias in last-laid eggs was present in complete broods, which had no nestling mortality, suggesting that primary sex ratio manipulation was involved. However, a small shift in the direction of female-bias occurred as a result of a greater mortality of the more costly (male) nestlings. Female flickers may therefore attempt to minimize maladaptive brood reduction by allocating more of the cheaper sex to positions later in the laying sequence. • Population level offspring sex ratio of northern flickers did not differ from parity. • High-quality parents did not produce more males (the expensive sex). • Flickers allocated more females to last-hatched offspring within asynchronous broods. • Female bias in last-laid eggs was present in broods without nestling mortality. • Sex allocation was consistent with the 'intrabrood sharing-out hypothesis'. [ABSTRACT FROM AUTHOR]

Body size–dependent physiological effects of temperature influence individual growth, reproduction, and survival, which govern animal population responses to global warming. Considerable knowledge has been established on how such effects can affect population growth and size structure, but less is known of their potential role in temperature‐driven adaptation in life‐history traits. In this study, we ask how warming affects the optimal allocation of energy between growth and reproduction and disentangle the underlying fitness trade‐offs. To this end, we develop a novel dynamic energy budget integral projection model (DEB–IPM), linking individuals' size‐ and temperature‐dependent consumption and maintenance via somatic growth, reproduction, and size‐dependent energy allocation to emergent population responses. At the population level, we calculate the long‐term population growth rate (fitness) and stable size structure emerging from demographic processes. Applying the model to an example of pike (Esox lucius), we find that optimal energy allocation to growth decreases with warming. Furthermore, we demonstrate how growth, fecundity, and survival contribute to this change in optimal allocation. Higher energy allocation to somatic growth at low temperatures increases fitness through survival of small individuals and through the reproduction of larger individuals. In contrast, at high temperatures, increased allocation to reproduction is favored because warming induces faster somatic growth of small individuals and increased fecundity but reduced growth and higher mortality of larger individuals. Reduced optimum allocation to growth leads to further reductions in body size and an increasingly truncated population size structure with warming. Our study demonstrates how, by incorporating general physiological mechanisms driving the temperature dependence of life‐history traits, the DEB–IPM framework is useful for investigating the adaptation of size‐structured organisms to warming. [ABSTRACT FROM AUTHOR]

Background and Aims We examined the relationship between reproductive allocation and vegetative growth in three monoicous sexual systems of bryophytes. The sexual systems show a gradient of increasing distance between the sexes, from gonioautoicous to cladautoicous to rhizautoicous. Here, we investigated the following two hypotheses: (1) reproductive allocation differs between sexes and sexual systems, and male reproductive allocation increases with increasing distance between male and female gametangia; and (2) reproductive allocation is negatively related to vegetative growth. Methods We sampled the three sexual systems, represented by three moss species of the genus Fissidens in the Atlantic Forest of Southeastern Brazil. Ramets were washed in the laboratory; the reproductive structures were detached from the vegetative ramets and sorted regarding sex and individual, dried at 70 °C for 72 h, and weighed in an ultramicrobalance. We calculated the mean reproductive and vegetative mass and reproductive allocation and used generalized linear models to test our predictions. Key Results Reproductive allocation differed between species and sexes. It was higher in the rhizautoicous than in the cladautoicous and gonioautoicous species. Mean reproductive allocation was greater in males than in females of the rhizautoicous species, greater in females than males of the cladautoicous species, and did not differ between the sexes in the gonioautoicous species. Estimates of reproductive and vegetative mass were positively related in females of the rhizautoicous species. Vegetative mass was not related to reproductive allocation in the gonioautoicous species, but negatively related to reproductive allocation in the male and female branchlets of the cladautoicous species and in the female ramets of the rhizautoicous species. Conclusions The reproductive allocation patterns differ between the rhizautoicous species and the 'truly' monoicous species, with shorter intersexual distances, which implies that our hypotheses were supported only in part. We suggest that the hypotheses should be reformulated and tested further by comparing 'truly' monoicous species with dioicous species and by including other genera. [ABSTRACT FROM AUTHOR]

Sexual size dimorphism (SSD) is caused by differences in selection pressures and life‐history trade‐offs faced by males and females. Proximate causes of SSD may involve sex‐specific mortality, energy acquisition, and energy expenditure for maintenance, reproductive tissues, and reproductive behavior. Using a quantitative, individual‐based, eco‐genetic model parameterized for North Sea plaice, we explore the importance of these mechanisms for female‐biased SSD, under which males are smaller and reach sexual maturity earlier than females (common among fish, but also arising in arthropods and mammals). We consider two mechanisms potentially serving as ultimate causes: (a) Male investments in male reproductive behavior might evolve to detract energy resources that would otherwise be available for somatic growth, and (b) diminishing returns on male reproductive investments might evolve to reduce energy acquisition. In general, both of these can bring about smaller male body sizes. We report the following findings. First, higher investments in male reproductive behavior alone cannot explain the North Sea plaice SSD. This is because such higher reproductive investments require increased energy acquisition, which would cause a delay in maturation, leading to male‐biased SSD contrary to observations. When accounting for the observed differential (lower) male mortality, maturation is postponed even further, leading to even larger males. Second, diminishing returns on male reproductive investments alone can qualitatively account for the North Sea plaice SSD, even though the quantitative match is imperfect. Third, both mechanisms can be reconciled with, and thus provide a mechanistic basis for, the previously advanced Ghiselin–Reiss hypothesis, according to which smaller males will evolve if their reproductive success is dominated by scramble competition for fertilizing females, as males would consequently invest more in reproduction than growth, potentially implying lower survival rates, and thus relaxing male–male competition. Fourth, a good quantitative fit with the North Sea plaice SSD is achieved by combining both mechanisms while accounting for sex‐specific costs males incur during their spawning season. Fifth, evolution caused by fishing is likely to have modified the North Sea plaice SSD. [ABSTRACT FROM AUTHOR]

Organisms must overcome environmental limitations to optimize their investment in life history stages to maximize fitness. Human-induced climate change is generating increasingly variable environmental conditions, impacting the demography of prey items and, therefore, the ability of consumers to successfully access resources to fuel reproduction. While climate change effects are especially pronounced in the Arctic, it is unknown whether organisms can adjust foraging decisions to match such changes. We used a 9-year blood plasma δ13C and δ15N data set from over 700 pre-breeding Arctic common eiders (Somateria mollissima) to assess breeding-stage and inter-annual variation in isotopic niche, and whether inferred trophic flexibility was related to colony-level breeding parameters and environmental variation. Eider blood isotope values varied both across years and breeding stages, and combined with only weak relationships between isotopic metrics and environmental conditions suggests that pre-breeding eiders can make flexible foraging decisions to overcome constraints imposed by local abiotic conditions. From an investment perspective, an inshore, smaller isotopic niche predicted a greater probability to invest in reproduction, but was not related to laying phenology. Proximately, our results provide evidence that eiders breeding in the Arctic can alter their diet at the onset of reproductive investment to overcome increases in the energetic demand of egg production. Ultimately, Arctic pre-breeding common eiders may have the stage- and year-related foraging flexibility to respond to abiotic variation to reproduce successfully. [ABSTRACT FROM AUTHOR]

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Effects of global climate change on population persistence are often mediated by life‐history traits of individuals, especially the timing of somatic growth, reproductive development, and reproduction itself. These traits can vary among age groups and between the sexes, a result of differential life‐history tactics and levels of lifetime reproductive investment. Unfortunately, the trait data necessary for revealing sex‐specific breeding behaviors and use of breeding cues over reasonably large geographic areas remain sparse for most taxa. In this study, we assembled and analyzed a new reproductive trait base for the North American deer mouse (Peromyscus maniculatus) from digitized natural history specimens and field censuses. We used the data to reconstruct sex‐specific breeding phenologies and their drivers within and among North American ecoregions. Male and female phenologies varied across the geographic range of this species, with discordance in timing and intensity being highest in regions of lower seasonality (and longer breeding seasons). Reliance on environmental variables as breeding cues also appeared to vary in a sex‐specific manner, being most similar for photoperiod and least similar for temperature (positive male response and negative female response); in addition, model validation indicated that phenological models generalized better for males than for females. Finally, our individual‐level trait data also show that male reproductive investment (quantified as relative testis size) varies across the vastly different abiotic and social (i.e., female breeding) contexts studied here. By harmonizing across a broad set of digital data resources, we demonstrate the potential to uncover drivers of phenological variation within species and inform global change predictions at multiple scales of biological organization. [ABSTRACT FROM AUTHOR]

Abstract While uncovering the costs and benefits of polyandry has attracted considerable attention, assessing the net effect of sexual selection on population fitness requires the experimental manipulation of female mating over generations, which is usually only achievable in laboratory populations of arthropods. However, knowing if sexual selection improves or impairs the expression of life‐history traits is key for the management of captive populations of endangered species, which are mostly long‐lived birds and mammals. It might therefore be questionable to extrapolate the results gathered on laboratory populations of insects to infer the net effect of sexual selection on populations of endangered species. Here, we used a longitudinal dataset that has been collected on a long‐lived bird, the houbara bustard, kept in a conservation breeding program, to investigate the effect of enforced monoandry on female investment into reproduction. In captivity, female houbara bustards are artificially inseminated with sperm collected from a single male (enforced monoandry), or sequentially inseminated with semen of different males (polyandry), allowing postcopulatory sexual selection to operate. We identified female lines that were produced either by monoandrous or polyandrous inseminations over three generations, and we compared reproductive investment of females from the two mating system groups. We found that females in the polyandrous lines had higher investment into reproduction as they laid more eggs per season and produced heavier hatchlings. Higher reproductive investment into reproduction in the polyandrous lines did not result from inherited differences from females initially included in the two mating system groups. These results show that removal of sexual selection can alter reproductive investment after only few generations, potentially hindering population fitness and the success of conservation breeding programs.

Abstract Effects of global climate change on population persistence are often mediated by life‐history traits of individuals, especially the timing of somatic growth, reproductive development, and reproduction itself. These traits can vary among age groups and between the sexes, a result of differential life‐history tactics and levels of lifetime reproductive investment. Unfortunately, the trait data necessary for revealing sex‐specific breeding behaviors and use of breeding cues over reasonably large geographic areas remain sparse for most taxa. In this study, we assembled and analyzed a new reproductive trait base for the North American deer mouse (Peromyscus maniculatus) from digitized natural history specimens and field censuses. We used the data to reconstruct sex‐specific breeding phenologies and their drivers within and among North American ecoregions. Male and female phenologies varied across the geographic range of this species, with discordance in timing and intensity being highest in regions of lower seasonality (and longer breeding seasons). Reliance on environmental variables as breeding cues also appeared to vary in a sex‐specific manner, being most similar for photoperiod and least similar for temperature (positive male response and negative female response); in addition, model validation indicated that phenological models generalized better for males than for females. Finally, our individual‐level trait data also show that male reproductive investment (quantified as relative testis size) varies across the vastly different abiotic and social (i.e., female breeding) contexts studied here. By harmonizing across a broad set of digital data resources, we demonstrate the potential to uncover drivers of phenological variation within species and inform global change predictions at multiple scales of biological organization.

Mate choice is an important cause of natural and sexual selection, driving the evolution of ornaments and promoting diversification and speciation. Mate choice decisions arise from the interaction of several components, and knowledge of whether they interact, and how, is crucial for understanding their contributions to selection. Here we focus on the relationship between preference functions (attractiveness ranking of prospective mates) and choosiness (effort invested in obtaining the preferred mate) and test the hypothesis that they are independent components of mate choice decisions. We examine individual variation in preference functions and choosiness for call duration in female Hyla versicolor treefrogs and show that measures describing preference functions and choosiness are not correlated. We also found a suggestive but inconclusive pattern that both components are influenced by different factors (body measures and hormones). Independence of preference and choosiness suggests that the joint study of variation in both components is required to gain a complete understanding of how mate choice contributes to sexual selection and speciation. [ABSTRACT FROM AUTHOR]

Pelagic eggs and larvae of many coral reef fishes will encounter a dynamic and risky environment as they disperse between the reef and offshore habitats. Life-history theory predicts that spawning adults should synchronize their reproductive effort with specific environmental conditions that facilitate offspring survival. Favourable conditions for reproduction may be determined by local environmental conditions at the spawning site, or signalled by larger-scale environmental cues, such as the lunar cycle. Multiple cues may interact in complex ways to cause additional variation in spawning intensity. We evaluated a set of environmental variables that potentially determine temporal and spatial variation in spawning patterns of a highly iteroparous fish, the sixbar wrasse (Thalassoma hardwicke). Specifically, we monitored focal territories of terminal-phase males over a 5-month period, quantified spawning activities, and evaluated a hierarchical set of predictive models using a model selection approach (AICc). Temporal variation in spawning (and population densities at the spawning site) was most strongly associated with the lunar cycle and maximal around the new moon. Local hydrodynamic conditions and other environmental variables observable at the spawning site were less strongly correlated with temporal variation in spawning. Territory proximity to the reef edge was a strong predictor of spatial variation in spawning intensity; territories closest to the reef edge experienced more spawning. These observations suggest that females make predictable decisions about where and when they spawn. Females appear to recognize strong, persistent spatial gradients in spawning habitat quality, and primarily vary their spawning effort in accordance with a large-scale environmental cue (the lunar cycle). [ABSTRACT FROM AUTHOR]

Nutritional stress in females may have adverse reproductive effects such as reduced fertility and high juvenile offspring mortality. In this study, we investigated the effects of dietary stress on the reproductive output of the scorpion Tityus pusillus Pocock, 1893, in which we tested the hypothesis that compared with well-fed females, those subjected to nutritional stress would have a longer gestational period, produce offspring of lower weight, and suffer higher rates of mortality rates. Females were mated and divided into two treatment groups: those fed weekly (n = 37) and those fed on alternate weeks (n = 43). Compared with the well-fed females, we observed higher mortality (81.4% vs. 59.5%), a longer gestational period (21.3 vs. 12.7 weeks), and a larger number of offspring, albeit with higher mortality (8 and 64.1% vs, 3.5 and 45.2%, respectively) in the less frequently fed females. However, litter weights in both groups were found to be similar (less fed: 0.013 g; well fed, 0.014 g). These findings reveal that nutritional stress causes changes in the progeny of inadequately fed T. pusillus females, thereby contributing to higher offspring mortality, and indicate that T. pusillus females vary their reproductive strategies depending on resource availability. [ABSTRACT FROM AUTHOR]

The structural condition of feathers may generally have a decisive role in shaping the color properties of the plumage. However, the information content of structurally mediated color differences is poorly known. This makes it particularly hard to determine the meaning of color variation in pigment-free white plumage patches. The white wing patch of the collared flycatcher (Ficedula albicollis) is an important sexual trait, and changes in its reflectance are partly due to macrostructural condition. We used 2 years of macrostructural, reflectance, and breeding data from both sexes to examine whether wing patch macrostructure lends information content to actual reflectance in terms of reproductive effort and success. Macrostructure strongly predicted actual reflectance in males but only weakly in females. Furthermore, in males, feather vane width was related positively to current year reproductive effort, and negatively to previous year reproductive effort. This indicates that macrostructurally mediated reflectance attributes may inform the receiver not only of actual reproductive capacity but also of individual quality via reproductive costs. Significance statement: Coloration of animals takes a central place in their communication and in advertising reproductive abilities. Although white plumage is widespread among animals, usually we have little knowledge on how its structure is linked to reproduction. We investigated this link in a wild population of collared flycatchers. We demonstrated that white feather structure was related to coloration and with current year and previous year reproductive capabilities in males. Our results suggest that white feather structure has the potential to connect reproductive costs with coloration. [ABSTRACT FROM AUTHOR]

A way of untangling the trade-off between investment in current offspring versus self-maintenance and future reproductive success is to determine how both parents allocate food between themselves and their offspring according to food availability. The hoopoe, Upupa epops , is an excellent model to test hypotheses about these decisions, since it is a central-place forager, a short-lived species and it reproduces successfully in captivity. We created different conditions of food availability (abundant/scarce) at two stages of the nestling period and provided different prey qualities in terms of digestibility and/or size. We hypothesized that parents would prioritize current offspring over their own maintenance. We predicted that (1) parents would offer their nestlings larger/more digestible prey, while they would eat smaller/less digestible prey and (2) when food was scarce, parents would not reduce the amount offered to nestlings. We found that both parents delivered high-quality prey to their nestlings at both stages and ate prey of lower digestibility in the early stage and smaller prey in the late stage. These results support the expectations for central-place foragers, as adults delivered the best prey to nestlings. When food availability was limited, parents at both nestling stages did not reduce the amount of consumed biomass. Despite nestlings receiving similar biomass in both treatments at the early stage, they experienced a reduction in biomass at the late stage when food was scarce. Therefore, hoopoes did not follow the typical strategy of a short-lived species, probably due to energy constraints related to a larger home range and prolonged nestling periods. In addition, females showed a more flexible response than males to changes in food availability, especially at the end of the breeding period. These sex-dependent responses could be related to different parental care investment at this stage when males take care of fledglings until independence and females are preparing for a second clutch. • We analysed how hoopoe parents allocate food between themselves and their offspring. • We used a captive population in an experimentally controlled scenario. • We manipulated the digestibility, size and quantity of available prey in the nest. • Both parents delivered the most profitable prey to offspring. • Parents did not fully compensate offspring for the reduced availability of food. [ABSTRACT FROM AUTHOR]

Seasonally breeding mammals must make constant adjustments in behavior and physiology to manage energetic trade-offs between survival and reproduction. Despite encountering high levels of climate and resource variability across the year, specialist Abert's squirrels (Sciurus aberti), lack the capacity to express hibernation or pronounced morphological adaptations to seasonality. Using accelerometer and GPS devices, we assessed how abiotic environmental factors, reproduction, and resource abundance influenced levels of activity and daily range size in a rural and food-supplemented suburban population of squirrels. We also quantified fecal cortisol metabolites (FCM) in squirrels to assess patterns of glucocorticoid secretion. While changes in weather predicted activity levels in both populations, seasonal variation in activity levels were reduced in food-supplemented compared to rural squirrels. In contrast to activity, daily range size was not affected by weather but was a better predictor of sex-specific reproductive investment. Comparisons between populations suggest that food-supplemented squirrels forage more efficiently within smaller areas. Across both sexes and populations, squirrels showed no sexual dimorphism in body size, no major patterns of seasonal weight change, and no associations between body mass and FCM concentrations; however, FCMs were lower in the food-supplemented compared to rural population during late-spring. Taken together, activity levels and FCM concentrations appear primarily influenced by weather and seasonal fluctuations in food availability, whereas daily range size reflects sexual asymmetries in seasonal reproductive investment. Overall, squirrels appear to rely largely on behavioral adjustments to cope with novel environmental heterogeneity, rather than changes in morphology or GC secretion. [ABSTRACT FROM AUTHOR]

1. Environmental stressors such as acidification modify community composition in freshwater habitats through their direct and indirect effects on individuals. However, the effect of acidification on various aspects of individual fitness is poorly known in aquatic insects, a key group in many freshwater habitats. 2. Here, the influence of acidification (acidity and Al toxicity), food quality and habitat properties on the reproduction of an acid‐tolerant mayfly Leptophlebia vespertina (Linnaeus, 1758) in a group of Central European lakes is explored. The focus is on last‐instar larvae as the short‐lived, semelparous adults cannot mitigate stress experienced by the larvae. 3. It is shown that the environment affects multiple determinants of individual reproductive output both directly by affecting body size and fecundity in last‐instar larvae, and indirectly by releasing the larvae from density dependence. Populations tended to be denser in more acidic sites and individuals in denser populations were substantially smaller and had lower size‐dependent fecundity and reproductive effort. All else being equal, larvae from colder sites were larger, suggesting an important role of the temperature‐size rule in this species. Size‐dependent fecundity and reproductive effort increased with better food conditions as expected, but neither reproductive measure was affected by acidity or temperature. Finally, a weak egg size‐number trade‐off with slightly smaller eggs in more fecund females was detected. 4. These results imply that indirect ecological feedbacks and food quality, rather than the direct effects of stressful environment, may dominate the effects of environmental stressors on the reproductive output of acid‐tolerant species such as L. vespertina. [ABSTRACT FROM AUTHOR]

Senescence occurs because of the decline of the strength of selection with age, allowing late-life reduced performances not being counter selected. From there, several phenomena may explain late-life reduced performances, such as the accumulation of deleterious mutations, the expression of pleiotropic genes or the existence of resource trade-offs between early and late performances. This latter phenomenon is at the core of the disposable soma theory of aging, which predicts that growth and early-life reproduction have costs that increase reproductive and actuarial senescence. Whereas the impact of the cost of early reproduction on reproductive and actuarial senescence has been extensively studied, that of the cost of growth remains overlooked and often inconclusive, possibly because of confounding effects associated with the procedures used to manipulate growth rate. Here, we investigated the cost of growth rate and its impact on reproductive senescence and longevity of females of the mealworm beetle, Tenebrio molitor. For this purpose, we generated insects with contrasted growth rates by raising groups of them in conditions below, above and optimal relative humidity (RH: 55, 85 and 70%, respectively) during the larval stage. The resulting adult females then bred, under the same optimal RH conditions, early in life, then later in life and were followed there until death. We found that larvae grown under the highest relative humidity exhibited the highest larval growth rate, thanks to both shorter growth duration and the achievement of heavier pupae mass. Adult females from this favorable growing condition lived longer, were more fecund early in life, but suffered from lower late-life reproductive investment. Our study shows that growth rate, which is highly dependent on the early-life environment, is an important factor modulating adult reproductive senescence, through the occurrence of early-late life trade-offs.

Abstract Sexually reproducing organisms face a strong selective pressure to find a mate and ensure reproduction. An important criterion during mate‐selection is to avoid closely related individuals and subsequent potential fitness costs of resulting inbred offspring. Inbreeding avoidance can be active through kin recognition during mate choice, or passive through differential male and female‐biased sex ratios, which effectively prevents sib‐mating. In addition, sex allocation, or the resources allotted to male and female offspring, can impact mating and reproductive success. Here, we investigate mate choice, sex ratios, and sex allocation in dispersing reproductives (alates) from colonies of the termite Cubitermes tenuiceps. Termites have a short time to select a mate for life, which should intensify any fitness consequences of inbreeding. However, alates did not actively avoid inbreeding through mate choice via kin recognition based on genetic or environmental cues. Furthermore, the majority of colonies exhibited a female‐biased sex ratio, and none exhibited a male‐bias, indicating that differential bias does not reduce inbreeding. Sex allocation was generally female‐biased, as females also were heavier, but the potential fitness effect of this costly strategy remains unclear. The bacterium Wolbachia, known in other insects to parasitically distort sex allocation toward females, was present within all alates. While Wolbachia is commonly associated with termites, parasitism has yet to be demonstrated, warranting further study of the nature of the symbiosis. Both the apparent lack of inbreeding avoidance and potential maladaptive sex allocation implies possible negative effects on mating and fitness.

The terminal investment hypothesis (TIH) predicts that individuals with favorable prospects for future reproduction (i.e., high residual reproductive value, RRV) should moderate current reproductive investment in favor of growth, survival, and future reproduction, whereas those with low RRV should "terminally invest" by diverting somatic resources towards current reproduction at the expense of future reproduction. However, support for the TIH in wild animal populations is fragmentary, and the ecological contexts of terminal investment remain poorly known. We report a remarkable case of simultaneous terminal investment involving five sympatric species of the electric knifefish genus Brachyhypopomus, from Amazonian floodplain and terra firme stream habitats. We found that terminal investment is synchronized by seasonal breeding, in response to circannual environmental variation in mortality risk. Four species exhibit a uniseasonal iteroparous (annual) life history with complete post‐reproductive mortality after a single breeding season. One species (Brachyhypopomus beebei) exhibits a 2‐year multiseasonal iteroparous life history with breeding in two seasons and post‐reproductive mortality after the second. In mature females and (most) males of the annual species, as well as in both mature female and male second‐year (but not first‐year) B. beebei, we documented an increase in two metrics of reproductive effort (size‐adjusted gonad mass and electric signal amplitude) and a concomitant reduction in somatic condition (size‐adjusted somatic mass), all in response to proximity to the end of the common breeding season, when RRV approximates zero. In mature first‐year B. beebei, we documented neither an increase in reproductive effort nor a decline in somatic condition, implying an alternative strategy of reproductive restraint. Our findings support Kirkwood's disposable soma theory, which posits that death by reproductive exhaustion can be delayed if terminal investment is replaced by reproductive restraint, allowing individuals to survive and breed in a subsequent season. Deferral of the terminal investment response in annual species, and the origin of a gonadal regression‐regeneration sequence, may open pathways for rapid evolutionary transitions to multiseasonal iteroparity. Excepting the age (year‐group) dependency of terminal investment in B. beebei, we were unable to identify intrinsic cues or extrinsic environmental cues for the terminal investment response in Brachyhypopomus. [ABSTRACT FROM AUTHOR]

While genetic variation is of crucial importance for organisms to be able to adapt to their ever-changing environments over generations, cognitive processes can serve the same purpose by acting at shorter time scales. Cognition, and its resulting behaviour, allows animals to display flexible, fast and reversible responses that, without implying a genetic change, are crucial for adaptation and survival. In the research field on sexual conflict, where studies focus on male and female mating strategies that increase the individual's reproductive fitness while forcing a cost on the partner, the role that cognition may play in how such strategies can be optimised has been widely overlooked. However, a careful analysis of behavioural studies shows that animals can develop and change their responses depending on what they perceive as well as on what they can predict from their experience, which can be of prime importance for optimising their reproductive fitness. As will be reviewed here, largely psychological processes, such as perception, memory, learning and decision-making, can not only modulate sexual conflict, but can also have a big impact on the reproductive success of a given individual. This review highlights the need for a more integrative view of sexual conflict where cognitive processes are also considered as a fundamental part of an animal's adaptive mating response. [ABSTRACT FROM AUTHOR]

Environmental challenges, such as fluctuations in food availability, could influence reproductive investment. If resource availability is poor, individuals need to decide in which life‐history process they invest more energy and vital compounds, which determine the cost of reproduction. In resource allocation, the physiological pathways have important roles. The aim of our study was to examine whether food availability influenced physiological traits (insulin‐like growth factor‐1 (IGF‐1) concentration, antioxidant capacity (OXY), level of oxidative damage (ROM) and haematocrit value) prior to egg‐laying in female canaries Serinus canaria. We also tested whether these physiological traits were associated with traits reflecting the reproductive investment in egg macro‐ (egg mass and yolk mass) and micronutrient content (eggshell biliverdin‐ and protoporphyrin‐based colouration). To test these questions we conducted a food restriction experiment with control and food‐restricted (72% of control food) groups. Our study showed that food‐restricted canary females delayed egg‐laying and the physiological traits differed between the groups. At the pre‐laying period, after 9–11 days of treatment, a reduction in plasma IGF‐1 concentration, ROM level and haematocrit value was detected in the control group, whereas in the food‐restricted group plasma IGF‐1 concentration increased, while ROM level and haematocrit value did not change. Plasma level of OXY was not influenced by treatment or breeding period. Plasma concentration of IGF‐1, haematocrit value and oxidative status before egg laying did not affect the egg characteristics. Our study highlights the importance of breeding stage when studying and interpreting the effects of food restriction on physiological traits of breeding birds. Moreover, our data suggest that nutritional limitation had an effect on the timing of egg‐laying that could be mediated by changes in physiological variables. [ABSTRACT FROM AUTHOR]

While genetic variation is of crucial importance for organisms to be able to adapt to their ever-changing environments over generations, cognitive processes can serve the same purpose by acting at shorter time scales. Cognition, and its resulting behaviour, allows animals to display flexible, fast and reversible responses that, without implying a genetic change, are crucial for adaptation and survival. In the research field on sexual conflict, where studies focus on male and female mating strategies that increase the individual’s reproductive fitness while forcing a cost on the partner, the role that cognition may play in how such strategies can be optimised has been widely overlooked. However, a careful analysis of behavioural studies shows that animals can develop and change their responses depending on what they perceive as well as on what they can predict from their experience, which can be of prime importance for optimising their reproductive fitness. As will be reviewed here, largely psychological processes, such as perception, memory, learning and decision-making, can not only modulate sexual conflict, but can also have a big impact on the reproductive success of a given individual. This review highlights the need for a more integrative view of sexual conflict where cognitive processes are also considered as a fundamental part of an animal’s adaptive mating response.

Environmental challenges, such as fluctuations in food availability, could influence reproductive investment. If resource availability is poor, individuals need to decide in which life‐history process they invest more energy and vital compounds, which determine the cost of reproduction. In resource allocation, the physiological pathways have important roles. The aim of our study was to examine whether food availability influenced physiological traits (insulin‐like growth factor‐1 (IGF‐1) concentration, antioxidant capacity (OXY), level of oxidative damage (ROM) and haematocrit value) prior to egg‐laying in female canaries Serinus canaria. We also tested whether these physiological traits were associated with traits reflecting the reproductive investment in egg macro‐ (egg mass and yolk mass) and micronutrient content (eggshell biliverdin‐ and protoporphyrin‐based colouration). To test these questions we conducted a food restriction experiment with control and food‐restricted (72% of control food) groups. Our study showed that food‐restricted canary females delayed egg‐laying and the physiological traits differed between the groups. At the pre‐laying period, after 9–11 days of treatment, a reduction in plasma IGF‐1 concentration, ROM level and haematocrit value was detected in the control group, whereas in the food‐restricted group plasma IGF‐1 concentration increased, while ROM level and haematocrit value did not change. Plasma level of OXY was not influenced by treatment or breeding period. Plasma concentration of IGF‐1, haematocrit value and oxidative status before egg laying did not affect the egg characteristics. Our study highlights the importance of breeding stage when studying and interpreting the effects of food restriction on physiological traits of breeding birds. Moreover, our data suggest that nutritional limitation had an effect on the timing of egg‐laying that could be mediated by changes in physiological variables.

The balance between risk and benefit of exploiting resources drives life‐history evolution in organisms. Predators are naturally recognized as major drivers of the life‐history evolution of their prey. Although prey may also influence the life‐history evolution of their predators in the context of an evolutionary arms race, there is far more evidence of the role of predators than of prey.The goal of this study was to investigate the role of prey in life‐history evolution of predators using ladybird beetle predators of aphids and coccids. These particular ladybirds and their prey were chosen because literature shows that the pace of life of aphids is faster than that of coccids and this difference is reflected in the life histories of the ladybirds that specialize on feeding on aphids or coccids.Thirty‐four species of ladybird predators of aphids and eight of coccids belonging to five different tribes were collected and reared in the laboratory. The females were weighed as well as their eggs, and their reproductive investment estimated as the number of ovarioles. Phylogenetic relatedness was controlled for in the statistical analyses.Controlling for female mass revealed that ladybird predators of aphids lay bigger eggs than ladybird predators of coccids. This difference is not influenced by phylogenetic relatedness but only by the type of prey eaten. We suggest that ladybird predators of coccids lay smaller eggs because neonate larvae do not have to search, catch, and subdue prey. Both types of ladybirds have a similar reproductive investment relative to their body mass when phylogeny is controlled for.Recognizing the influence of prey on the life‐history evolution of predators is important for understanding food web dynamics. From an applied perspective, this fine evolutionary tuning of prey–predator relationships should be used to guide and increase the efficiency of biological control programs. [ABSTRACT FROM AUTHOR]

While uncovering the costs and benefits of polyandry has attracted considerable attention, assessing the net effect of sexual selection on population fitness requires the experimental manipulation of female mating over generations, which is usually only achievable in laboratory populations of arthropods. However, knowing if sexual selection improves or impairs the expression of life‐history traits is key for the management of captive populations of endangered species, which are mostly long‐lived birds and mammals. It might therefore be questionable to extrapolate the results gathered on laboratory populations of insects to infer the net effect of sexual selection on populations of endangered species. Here, we used a longitudinal dataset that has been collected on a long‐lived bird, the houbara bustard, kept in a conservation breeding program, to investigate the effect of enforced monoandry on female investment into reproduction. In captivity, female houbara bustards are artificially inseminated with sperm collected from a single male (enforced monoandry), or sequentially inseminated with semen of different males (polyandry), allowing postcopulatory sexual selection to operate. We identified female lines that were produced either by monoandrous or polyandrous inseminations over three generations, and we compared reproductive investment of females from the two mating system groups. We found that females in the polyandrous lines had higher investment into reproduction as they laid more eggs per season and produced heavier hatchlings. Higher reproductive investment into reproduction in the polyandrous lines did not result from inherited differences from females initially included in the two mating system groups. These results show that removal of sexual selection can alter reproductive investment after only few generations, potentially hindering population fitness and the success of conservation breeding programs. [ABSTRACT FROM AUTHOR]

Premise: Unlike most flowering plants, orchid flowers have under‐developed ovules that complete development only after pollination. Classical studies reported variation in the stage in which ovule development is arrested, but the extent of this variation and its evolutionary and ecological significance are unclear. Methods: Here, we used light microscopy to observe ovule development at anthesis for 39 species not previously studied and surveyed the literature gaining information on 94 orchid species. Tropical and temperate members of all five orchid subfamilies as well as species with contrasting pollination strategies (rewarding versus deceptive) and life forms (epiphytic versus terrestrial) were represented. We analyzed the data using statistical comparisons and a phylogenetic generalized least square (PGLS) analysis. Results: Apostasioideae, the sister to the rest of the orchids, have mature ovules similar to other Asparagales, while under‐differentiated ovules are present in the other subfamilies. Ovule developmental stages showed high variation even among closely related groups. Ovules were more developed in terrestrial than in epiphytic, in temperate than in tropical, and in rewarding than in deceptive pollination orchid species. This latter comparison was also significant in the PGLS analysis. Conclusions: These results suggest that ovule developmental stage in orchids can be shaped by ecological factors, such as seasonality and pollination strategy, and can be selected for optimizing female reproductive investment. [ABSTRACT FROM AUTHOR]

Understanding how organisms manage life history trade-offs under variable environmental conditions is an aim that is central to ecology. Comparing modern reproductive data with those from historical studies can increase understanding of the range of historical conditions that have acted on a given species over time. We use recent (2008-2010) and historical (1960s-1980s) reproductive data from a single study colony, Mandarte Island, Canada, to help understand the recent population declines experienced by the Glaucous-winged Gull (Larus glaucescens) in North America's Salish Sea, a highly urbanized area. Because this long-lived species has also undergone regional long-term declines in reproductive investment via decreasing egg and clutch size, we assessed whether modern reproductive outcomes were similarly affected. Although our statistical power was hampered by small sample sizes, it appears that hatching success declined over time, from 0.83 (1960s) and 0.76 (1970s-1980s) to 0.60 (2008-2010). An apparent decline in nesting success, from 0.63 (1962) to 0.52 (this study), was not statistically significant. Recent clutch sizes showed intra-seasonal declines, a pattern unchanged from historical trends. In contrast, egg mass historically was constant within a given nesting season, but recent egg-mass data show intra-seasonal declines. We conclude that most gulls currently breeding on Mandarte Island cannot attain historical levels of reproductive success — perhaps because of declining environmental quality in the form of reduced availability of high-quality fish prey — although some high-quality pairs in this population are still able to maximize reproductive output. Our study highlights the importance of long-term study systems for identifying consequences of large-scale ecosystem changes; however, methodological clarity is essential to ensure data comparability through time. Ultimately, further study is needed to identify the drivers of reproductive changes in this population, something that could be used to inform future management decisions.

The aim of this study was to confirm the type of protandry adopted by M. rhizophorae and to describe the size at which sex change occurs in order to test predictions of sex allocation theory. The reproductive output also was investigated, based on fecundity and embryo volume. Specimens were collected cohabiting burrows built by mud shrimps Upogebia omissa in an estuary region in the northeast of Brazil. The body size (carapace length, CL) and sex of the shrimps were recorded. Observations were made developmental stages of the embryos, fecundity, and embryo volume. A total of 204 M. rhizophorae individuals was sampled, of which 170 (83.3%) male phase (MP) and 34 (16.7%) female phase (FP) individuals. The body size (mean ± SD) of the individuals in the MP was smaller than in the FP: 3.91 ± 0.78 and 6.18 ± 0.52 mm CL, respectively. The size at which 50% of the shrimps changed to FP (CL50) was 5.62 ± 0.01 mm CL. Reproductive output (fecundity and embryo volume) increased linearly with shrimp body size. An increase in embryo size during development and the loss of embryos during final stage of development were recorded. In this study, the behaviour exhibited by M. rhizophorae (share a burrow with another shrimp species) was recorded for the first time, expanding knowledge about the ecology of this semi-terrestrial shrimp. Our results indicate the adoption of strict protandric hermaphroditism by M. rhizophorae. Our study supports the prediction of sex allocation theory that sex ratio is significantly biased towards the first-sex in sequential hermaphrodites. We also found evidence of possible trade-offs between the size in which the sex change occurs and the reproductive strategy exhibited by M. rhizophorae. [ABSTRACT FROM AUTHOR]

Many animals adjust their reproductive investment in line with their current competitive abilities. High-quality individuals may breed in the peak breeding period because they have a greater probability of finding high-quality mates, whereas low-quality individuals may breed in the off-peak period to avoid competing with high-quality rivals. We observed a wild population of the fiddler crab Austruca perplexa to investigate the waving rate of large and small males towards large and small females in the peak and off-peak breeding periods. We predicted that large males would invest more in courtship in the peak breeding period and invest less in the off-peak period, whereas small males would invest more in courtship when large males invest less. It was observed that large males waved their major claws more frequently in the peak breeding period than in the off-peak period and waved more towards large females, while small males waved more in the off-peak breeding period and their waving rates were not different towards large or small females. For small males, investing more in courtship in the off-peak breeding period may offer a greater probability of acquiring females than competing against large rival males in the peak breeding period. [ABSTRACT FROM AUTHOR]

Brain size exhibits significant changes within and between species. Evolution of large brains can be explained by the need to improve cognitive ability for processing more information in changing environments. However, brains are among the most energetically expensive organs. Enlarged brains can impose energetic demands that limit brain size evolution. The expensive tissue hypothesis (ETH) states that a decrease in the size of another expensive tissue, such as the gut, should compensate for the cost of a large brain. We studied the interplay between energetic limitations and brain size evolution in small mammals using phylogenetically generalized least squares (PGLS) regression analysis. Brain mass was not correlated with the length of the digestive tract in 37 species of small mammals after correcting for phylogenetic relationships and body size effects. We further found that the evolution of a large brain was not accompanied by a decrease in male reproductive investments into testes mass and in female reproductive investment into offspring number. The evolution of brain size in small mammals is inconsistent with the prediction of the ETH. [ABSTRACT FROM AUTHOR]

In scramble competition mating systems, males do not guard females and females usually mate polyandrously, leading to high levels of sperm competition. Mathematical models predict that males facing sperm competition can either decrease or increase their reproductive effort. To test how male reproductive responses vary according to sperm competition risk, we ran two experiments using the polyandrous gift‐giving spider Paratrechalea ornata. First, we tested whether males prefer substrates containing silk of unmated females than substrates containing silk of once‐mated females, competitor males or without silk. Males spent more time on substrates containing silk of females but showed no preference for unmated females, which indicates that males may optimize mate search by prioritizing substrates containing cues of potential mating partners. The lack of preference for unmated females suggests that males cannot detect female mating status from silk or that the costs of searching preferentially for unmated females are high in the field. Second, we tested whether males adjust prey‐gift construction when facing sperm competition risk. Experimental groups (substrate containing silk of an unmated female and silk of another male vs. substrate containing only silk of an unmated female) did not differ in the frequency of gift construction, latency to gift construction and number of flies added to the gift. However, males facing sperm competition risk constructed gifts with less silk, suggesting the occurrence of a less evident form of male mate choice based on differential allocation of resources to prey‐gift. Additionally, given the trade‐off between investing in prey‐gifts quantity or quality, a lower silk investment should enable males to increase the number of gifts constructed and the number of courted females. Taken together, our results indicate that males detect female and male pheromones on substrate and adjust the construction of prey‐gifts in response to apparent sperm competition risk. [ABSTRACT FROM AUTHOR]

This study analysed differences in the timing of egg extrusion, reproductive investment and spatial distribution between primiparous and multiparous females of the southern king crab (SKC) Lithodes santolla. Early publications had reported that, in the San Jorge Gulf (SJG; 45–47°S), Argentina, SKCs mated annually, mainly in December. In this work, in coastal areas of SJG, we found small females in postmoult with recently extruded eggs in September–October. At the same time, one SKC female fraction was in intermoult with eggs close to hatching. Evidence suggests that females with recently extruded eggs were primiparous, while females with eggs close to hatching were multiparous. Primiparous females were less fecund than multiparous females of the same size, but no differences were found in the egg dry mass between these female fractions. The size-frequency distribution observed suggests a spatial segregation between primiparous and multiparous females, with the former being concentrated in the coastal areas of SJG. Differences in reproductive traits between primiparous and multiparous females have been widely reported in crab species with determinate growth, but rarely in crabs with indeterminate growth as lithodids. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)