Biology subjects

Moiron, M.

Publications and source records attributed to Moiron, M..

9 recordsLinked to original sources

bioRxiv2026

Individual variation in glucocorticoid plasticity to temperature is not associated with reproductive success in a wild songbird population

Vertebrates cope with rapid temperature fluctuations by plastically adjusting their behaviour and physiology. This phenotypic plasticity is partly mediated by plastic changes in glucocorticoid levels; however, whether individual differences in endocrine plasticity are associated with fitness remains unknown. Here, we examined the relationship between individual variation in glucocorticoid plasticity in response to air temperature changes and reproductive success in a wild great tit population (Parus major). Over nine years, we collected repeated measurements of baseline and stress-induced corticosterone during nestling rearing. We found consistent reaction norm patterns in hormone response to temperature variation -- as shown in a previous study conducted over a shorter period. This provides robust evidence of individual differences in average hormone levels (intercepts) and the strength of the plastic response (slopes), indicating potential for evolution. However, neither intercepts nor slopes were associated with reproductive success (fledgling number or brood mass), suggesting that individual variation in endocrine plasticity was not under natural selection, at least within the environmental conditions experienced. This study provides a first empirical test of the evolutionary implications of endocrine plasticity in the wild and highlights the need to assess its fitness relevance under more extreme conditions, such as those expected under future climate scenarios.

evolutionary biology↗

bioRxiv2024

Indirect genetic effects increase the heritable variation available to selection and are largest for behaviours: a meta-analysis

The evolutionary potential of traits is governed by the amount of heritable variation available to selection. While this is typically quantified based on genetic variation in a focal individual for its own traits (direct genetic effects, DGEs), when social interactions occur, genetic variation in interacting partners can influence a focal individuals traits (indirect genetic effects, IGEs). Theory and studies on domesticated species have suggested IGEs can greatly impact evolutionary trajectories, but whether this is true more broadly remains unclear. Here we perform a systematic review and meta-analysis to quantify the amount of trait variance explained by IGEs and the contribution of IGEs to predictions of adaptive potential. We identified 180 effect sizes from 47 studies across 21 species and found that, on average, IGEs of a single social partner account for a small but statistically significant amount of phenotypic variation (0.03). As IGEs affect the trait values of each interacting group member and due to a typically positive - although statistically nonsignificant - correlation with DGEs (rDGE-IGE = 0.26), IGEs ultimately increase trait heritability substantially from 0.27 (narrow-sense heritability) to 0.45 (total heritable variance). This 66% average increase in heritability suggests IGEs can increase the amount of genetic variation available to selection. Furthermore, whilst showing considerable variation across studies, IGEs were most prominent for behaviours, and to a lesser extent for reproduction and survival, in contrast to morphological, metabolic, physiological, and development traits. Our meta-analysis therefore shows that IGEs tend to enhance the evolutionary potential of traits, especially for those tightly related to interactions with other individuals such as behaviour and reproduction. Lay SummaryPredicting evolutionary change is important for breeding better livestock and crops, for understanding how biodiversity arises and how populations respond to environmental change. Normally, these predictions are based on how the genetic variants in an organism influence its own traits (characteristics). However, when organisms socially interact, for instance by fighting or cooperating, then the genes in one individual can influence the traits of others, therefore affecting the potential for evolutionary change. We compared 47 studies across 21 animal species and found that the effect of the genes of a single social partner is small but statistically significant, while the total contribution of social genetic effects to evolutionary potential is large. These effects are particularly important for the evolution of animals behaviours and reproductive traits, but less so for other traits such as body size and physiology. We also found that, because an individual can interact with many others and influence them all, social interactions can substantially increase the potential for a population to evolve from generation to generation. Our results show how social interactions can potentially alter the evolution of those traits known to respond to social interactions in comparison to standard expectations.

evolutionary biology↗

bioRxiv2023

Rapid decline of prenatal maternal effects with age is independent of postnatal environment in a precocial bird

Maternal effects are an important source of phenotypic variation with potentially large fitness consequences, but how their importance varies with the quality of the environment across an individuals ontogeny is poorly understood. We bred Japanese quail (Coturnix japonica) of known pedigree and experimentally manipulated the quality of offspring diet, to estimate the importance of prenatal maternal effects in shaping variation in body mass from hatching to adulthood. Maternal genetic effects on body mass at hatching were strong, and largely caused by variation in egg mass, but their importance rapidly declined with age. Whereas there was a large effect of diet on growth, this did not affect the decline of maternal effects variance. The importance of additive genetic and residual variance increased with age, with the latter being considerably larger in the poor diet treatment. Hence, we found no evidence for prenatal maternal effect by postnatal environment interactions, and that prenatal maternal effects are rapidly replaced by direct additive genetic and residual effects when offspring start to develop outside the egg. Thereby these results shed new light on the dynamics of the role of maternal versus offspring genes across ontogeny and environments.

evolutionary biology↗

bioRxiv2022

Partitioning variance in a signaling trade-off under sexual selection reveals among-individual covariance in trait allocation

Understanding the evolution of traits subject to trade-offs is challenging because phenotypes can (co)vary at both the among- and within-individual levels. Among-individual covariation indicates consistent, possibly genetic, differences in how individuals resolve the trade-off, while within-individual covariation indicates trait plasticity. There is also the potential for consistent among-individual differences in behavioral plasticity, although this has rarely been investigated. We studied the sources of (co)variance in two characteristics of an acoustic advertisement signal that trade off with one another and are under sexual selection in the gray treefrog, Hyla chrysoscelis: call duration and call rate. We recorded males on multiple nights calling spontaneously and in response to playbacks simulating different competition levels. Call duration, call rate, and their product, call effort, were all repeatable both within and across social contexts. Call duration and call rate covaried negatively, and the largest covariance was at the among-individual level. There was extensive plasticity in calling with changes in social competition, and we found some evidence for among-individual variance in call rate plasticity. The significant negative among-individual covariance in trait values is perpendicular to the primary direction of sexual selection in this species, indicating potential limits on the response to selection.

animal behavior and cognition↗

bioRxiv2022

Great tits differ in glucocorticoid plasticity in response to spring temperature

Fluctuations in environmental temperature affect energy metabolism, stimulating the expression of phenotypic plasticity in behavioral and physiological traits. Vertebrate hormonal signals like glucocorticoids underpin environmentally-induced phenotypic plasticity, with changes in circulating concentrations orchestrating plastic changes in diverse traits. Climate change is predicted to alter temperature variation globally, making it imperative to evaluate whether free-living animal populations can cope adaptively. To evaluate their potential to respond to ongoing global change, we quantified individual variation in glucocorticoid plasticity to ambient temperature in wild great tits (Parus major). Using a reaction norm approach, we repeatedly sampled individuals for circulating glucocorticoid concentrations across five years. As expected, baseline and stress-induced glucocorticoid concentrations increased with lower ambient temperatures at the population and within-individual level. Moreover, we provide unique evidence that free-living individuals differ significantly in their plastic responses to temperature variation for both glucocorticoid traits, with some displaying greater plasticity than others. Average concentrations and degree of plasticity covaried for baseline glucocorticoids, indicating that these two reaction norm components are linked. Hence, individual variation in glucocorticoid plasticity to an important environmental factor exists in a wild population, representing a crucial step to assess the adaptive potential of vertebrates to endure current temperature fluctuations.

physiology↗

bioRxiv2022

Sexual selection moderates heat stress response in males and females

A widespread effect of climate change is the displacement of organisms from their thermal optima. The associated thermal stress imposed by climate change has been argued to have a particularly strong impact on male reproduction but evidence for this postulated sex-specific stress response is equivocal. One important factor that may explain intra- and interspecific variation in stress responses is sexual selection, which is predicted to magnify negative effects of stress. Nevertheless, empirical studies exploring the interplay of sexual selection and heat stress are still scarce. We tested experimentally for an interaction between sexual selection and thermal stress in the red flour beetle Tribolium castaneum by contrasting heat responses in male and female reproductive success between setups of enforced monogamy versus polygamy. We found that polygamy magnifies detrimental effects of heat stress in males but relaxes the observed negative effects in females. Our results suggest that sexual selection can reverse sex differences in thermal sensitivity, and may therefore alter sex-specific selection on alleles associated with heat tolerance. We argue that these findings have important implications for predicting the role of sexual selection for the adaptation to current global warming and increased frequency of extreme climatic events.

evolutionary biology↗

bioRxiv2021

Stronger net selection on males across animals

Sexual selection is considered the major driver for the evolution of manifold sex differences. However, the eco-evolutionary dynamics of sexual selection and their role for a populations adaptive potential to respond to environmental change have only recently been explored. Theory predicts that sexual selection promotes adaptation at a low demographic cost only if net selection is stronger on males compared to females. We used a comparative approach to show that net selection is indeed stronger in males in species prone to intense sexual selection. Given that both sexes share the vast majority of their genes, our findings corroborate the notion that the genome is often confronted with a more stressful environment when expressed in males. Collectively, our study supports a long-standing key assumption required for sexual selection to bolster adaptation, and intense sexual selection may therefore enable some species to track environmental change more efficiently. One sentence summaryComparative study finds support for stronger net selection in males.

evolutionary biology↗

bioRxiv2021

Die hard in Lake Bourget! The case of Planktothrix rubescens

Blooms of Planktothrix rubescens have been recorded for 15 years in Lake Bourget (France), from 1995 to 2009. Then, the presence of this filamentous and toxic cyanobacterium became anecdotic between 2010 and 2015 and it was clearly thought that such a proliferation was over. However, against all odds, blooms occurred again in 2016 and 2017 despite apparent very low phosphorus concentrations in surface waters of the lake. Aims of this study were thus to explain the reasons of this come back in order to propose scenarios likely to be helpful to stakeholders who need to know if such proliferations may occur again in the future. We show that phosphorus input, both from the main tributaries to the lake and possibly from the sediments, were likely the triggers of the new development of the cyanobacterium since a minimum autumn/winter inoculum of P. rubescens was detected the year before. Then, the bloom, that was observed deeper than previous years, was associated to a conjunction of factors already well-known to favour the development of this very competitive species (i.e. mild winter temperature, water column stability, available light at depth, surface water transparency, low predation, etc...). Although many factors and processes could account for the occurrence and bloom of the cyanobacterium, not observed, measured or taken into account here, a plausible scenario could be proposed and may be useful to deciders. One thing remains unclear: where do the cyanobacterium hides when it is not observed during the routine monitoring survey and thus from which place it could initiate its development (nearshore, in the pelagic zone, from the sediment?), unless it is simply not sampled and observed due to methodological bias.

ecology↗

bioRxiv2020

Defending as a unit: sex- and context-specific territorial defence in a duetting bird

Behaviours such as territorial defence represent functionally integrated traits that underlie multiple behavioural variables such as physical and acoustic responses. Characterizing the multivariate structure of such traits is fundamental to understand their evolution. In bird species that form stable pair bonds and are territorial year-round, both sexes are expected to defend their territory; however, the role that each sex plays in defending their shared territory remains largely unknown. Evidence for the sex-roles during territorial defence is mixed and sex- and context-specific characterizations of territorial defence embracing the multivariate nature of the trait are currently lacking. Here we investigated sex- and context-specific variation in a hypothesised latent variable called "territorial defence" and tested whether duets were part of territorial defence in a wild population of rufous hornero (Furnarius rufus). To do so, we combined a simulated territorial intrusion approach during nest building and provisioning contexts with a structural equation modelling approach. Our results showed that, in males and females, the six measured behavioural variables were linked by a single latent trait, territorial defence, in both contexts. Flights over the decoy and duet songs were equally good proxies of territorial defence. Although males were defending more the territory than females, pair members showed a positive correlation in their behaviour. The structural equation modelling framework enabled us to capture a complex correlation pattern among behavioural variables, expanding upon a classic body of research on territorial defence. Thus, the combination of classical behavioural approaches with sophisticated statistical analyses brings new exciting possibilities to the field of behavioural ecology. Significance statementTerritorial defence is a key behaviour in territorial species as it plays a major role in an individuals reproductive success and survival. Additionally, territorial defence has been proposed as one possible evolutionary driver of duetting behaviour, one of the most fascinating vocal behaviours in birds. As behaviours are evolutionary characters, they must be studied in a multivariate framework. In this study we focused on characterizing territorial defence during a simulated territorial intrusion in an integrative manner using a classical territorial intrusion framework. We did so in male and female rufous horneros (Aves: Furnaridae) across two breeding contexts, while simultaneously testing theoretical predictions about the role of duetting behaviour as key part of territorial defence. Overall, our study provides for the first time a sex- and context-comparison of the multivariate, latent variable "territorial defence" in duetting birds, while highlighting the potential of combining field behavioural approaches with structural equation modelling.

animal behavior and cognition↗