Biology subjects

Pilakouta, N.

Publications and source records attributed to Pilakouta, N..

8 recordsLinked to original sources

bioRxiv2026

Same-sex sexual behaviour reduces reproductive success but mitigates aggression in a subsocial insect

Same-sex sexual behaviour (SSB) is widely observed across taxa, yet its evolutionary maintenance remains debated and its fitness consequences remain surprisingly understudied. Here, we quantified the fitness consequences of male SSB in the burying beetle Nicrophorus vespilloides and tested three prominent hypotheses about its function: (i) that it provides practice for future mating, (ii) that it reduces tension through dominance assertion, and (iii) that it arises indirectly from indiscriminate mating. Males were observed in same-sex pairings to quantify SSB and then paired with females to measure their subsequent mating behaviour and reproductive success. Same-sex sexual behaviour was common, occurring in 55% of same-sex pairs, and was associated with reduced reproductive success driven by higher brood failure rates. Both males that initiated, and those that received, mounting attempts from other males suffered reduced fitness. Contrary to the practice hypothesis, SSB did not increase mating speed with females and was associated with reduced mating frequency. However, SSB was associated with reduced aggression, supporting the hypothesis that SSB reduces tension through dominance establishment. Our findings show that SSB can reduce reproductive success but may be maintained due to a beneficial reduction in aggression.

animal behavior and cognition↗

bioRxiv2026

From individuals to ecosystems: carrion beetle responses to heatwaves impact nutrient cycling

Climate extremes, such as heatwaves, are becoming more frequent and severe, leading to significant disruptions in key ecosystem processes. The direct effects of heatwaves on these processes have thus received increasing attention, yet the indirect effects of heatwaves, as mediated through animal behavioural responses, are still unknown. Insects play a fundamental role in carrion decomposition by modifying carcasses and regulating nutrient transfer to soils. Understanding how insect responses to climate extremes scale up to ecosystem processes is therefore crucial. In this study, we used a widespread carrion beetle, the burying beetle Nicrophorus vespilloides, to experimentally investigate the direct and indirect effects of a simulated heatwave on carrion decomposition dynamics, and the consequences for soil nutrient cycling. We found that burying beetle presence increased carcass mass loss by 355% under ambient temperatures, and that this was accompanied by significant increases in dissolved organic carbon (+86%), ammonium (+71%), and nitrate (+47%) concentrations. However, the positive effects of burying beetle presence on carcass mass loss were severely diminished by heat stress. Path analyses revealed that this was related to marked reductions in certain beetle behaviours, such as carcass preparation, as well as a reduction in brood size. These behavioural and reproductive shifts were, in turn, linked to decreased soil nitrate concentrations and soil moisture. Together, these findings demonstrate that the indirect effects of heatwaves on decomposition processes, as mediated by shifts in the behaviour and traits of animal ecosystem engineers, can be as important as their direct effects. Such indirect effects must therefore be incorporated into our understanding of how key ecosystem processes respond to climate extremes.

ecology↗

bioRxiv2026

Mixed signals: heat stress alters chemical profiles and increases same-sex sexual behaviour in an insect

Rising temperatures linked to global climate change can disrupt the chemical communication that animals rely on for reproduction. Arthropods are particularly vulnerable due to their limited ability for thermoregulation and their reliance on cuticular hydrocarbons (CHCs), which have a dual role in social communication and heat protection. Heat-induced changes in cuticular composition may therefore lead to mate recognition errors. We tested this in the burying beetle Nicrophorus vespilloides, by exposing males to either benign temperatures (20{degrees}C) or a simulated 3-day heatwave (26{degrees}C). We recorded the frequency of same-sex sexual behaviour under these contrasting thermal conditions and examined associated changes in the males' cuticular profiles. Our results show a higher rate of same-sex mounting under heat stress, with the CHCs of heat-stressed males shifting toward more saturated, longer-chained compounds and more female-like compounds. We also found a positive association between chain length and the frequency of same-sex mounting, suggesting a trade-off between the social communication and waterproofing functions of CHCs. Overall, our findings provide evidence for a causal effect of heat on same-sex sexual behaviour, which may be partly explained by changes in cuticular lipids. Such disruption of chemical communication could have major consequences for animal reproduction in a warming world.

ecology↗

bioRxiv2025

Parallel adaptation to geothermally-warmed habitats due to common structural variation and functional developmental pathways

Climate change is causing rapid increases in temperature which drives genomic changes tied to adaptation. However, predicting the outcomes of climate change presents challenges as the anticipated conditions have yet to be experienced by natural populations. Modelling and lab experiments suggest that natural populations will experience shifts in life history, physiology, phenology, and ecology, but the underlying genomic mechanisms involved are unknown. However, some contemporary natural populations experience habitat warming through geothermal activity and can provide valuable insights into evolutionary responses. Geothermally warmed habitats should impose strong selection on ectotherms compared to ambient habitats as they increase metabolic demands, alter developmental processes, and offer novel ecological conditions. We leveraged Icelandic threespine sticklebacks (Gasterosteus aculeatus) from populations that have adaptively diverged along a geothermal/ambient habitat axis. We obtained 173,485 single nucleotide polymorphisms (SNPs) across four independent instances of population divergence using whole genome sequencing. While the majority of genomic differentiation between geothermal/ambient ecotypes was non-parallel, the MAPK signalling pathway appeared across all ecotype pairs. We also identified a putative inversion located on chromosome XXI which appears to drive parallel genomic differentiation between geothermal and ambient ecotypes. Candidate genes within the putative inversion correspond to metabolic adaptations, including regulation of appetite and fat content. Appetite level showed strong heritable divergence between ecotypes, while the rate of weight loss during starvation and fat levels differed between ecotypes. Overall, both polygenic adaptation and parallel structural variation appeared to be key genomic mechanisms for adaptation to geothermally warmed environments. While allelic divergence was largely unique across populations, it resulted in similar functional phenotypic outcomes. Thus, structural and allelic variation both operate to facilitate adaptation to warming environments. Therefore, while management from a genomic perspective will play a role in mitigating the effects of climate change, this study suggests that consideration of functional molecular pathways will be key to conservation but with precise changes being difficult to predict due to the highly polygenic nature of thermal adaptation.

evolutionary biology↗

bioRxiv2022

Effects of temperature on mating behaviour and mating success: a meta-analysis

O_LIIn light of global climate change, there is a pressing need to understand how populations will respond to rising temperatures. Understanding the effects of temperature changes on mating behaviour is particularly important, given its implications for population viability. C_LIO_LITo this end, we performed a meta-analysis of 53 studies to examine how temperature changes influence mating latency, choosiness, and mating success. We hypothesized that if higher temperatures make mate searching and mate assessment more costly due to an elevated metabolism, this may lead to a reduction in mating latency and choosiness, thereby increasing overall mating success. C_LIO_LIWe found no evidence for a global effect of temperature on mating latency, choosiness, or mating success. There was an increase in mating success when animals were exposed to higher temperatures during mating, but not when they were exposed before mating. C_LIO_LIInterestingly, in a subset of studies that measured both mating latency and mating success, there was a strong negative relationship between the effect sizes for these traits. This suggests that a decrease in mating latency at higher temperatures was associated with an increase in mating success and vice versa. C_LIO_LIIn sum, our meta-analysis provides new insights into the effects of temperature on mating patterns. The absence of a consistent directional effect of temperature on mating behaviours and mating success suggests it may be difficult to predict changes in the strength of sexual selection in natural populations in a warming world. Nevertheless, there is some evidence that (i) higher temperatures during mating may lead to an increase in mating success and that (ii) an increase in mating success is associated with a decrease in mating latency. C_LI

animal behavior and cognition↗

bioRxiv2019

Reduction in standard metabolic rate after multigenerational exposure to elevated temperatures in the wild

O_LIIn light of global climate change, there is a pressing need to understand and predict the capacity of populations to respond to rising temperatures. Metabolic rate is a key trait that is likely to influence the ability to cope with climate change. Yet, empirical and theoretical work on metabolic rate responses to temperature changes has so far produced mixed results and conflicting predictions. C_LIO_LIOur study addresses this issue using a novel approach of comparing fish populations in geothermally warmed lakes and adjacent ambient-temperature lakes in Iceland. This unique natural experiment provides repeated and independent examples of populations experiencing contrasting thermal environments for many generations over a small geographic scale, thereby avoiding the confounding factors associated with latitudinal or elevational comparisons. Using Icelandic sticklebacks from three warm and three cold habitats, we measured individual metabolic rates across a range of acclimation temperatures to obtain reaction norms for each population. C_LIO_LIWe found a general pattern for a lower standard metabolic rate in sticklebacks from warm habitats when measured at a common temperature, as predicted by Kroghs rule. Metabolic rate differences between warm- and cold-habitat sticklebacks were more pronounced at more extreme acclimation temperatures, suggesting the release of cryptic genetic variation upon exposure to novel conditions, which can reveal hidden evolutionary potential. We also found a stronger divergence in metabolic rate between thermal habitats in allopatry than sympatry, indicating that gene flow may constrain physiological adaptation when dispersal between warm and cold habitats is possible. C_LIO_LIIn sum, our study suggests that fish may diverge toward a lower standard metabolic rate in a warming world, but this might depend on connectivity and gene flow between different thermal habitats. C_LI

physiology↗

bioRxiv2019

Temperature preference does not evolve in sticklebacks despite multigenerational exposure to elevated temperatures

Given the threat of climate change to biodiversity, a growing number of studies are investigating the potential for organisms to adapt to rising temperatures. Earlier work has predicted that physiological adaptation to climate change will be accompanied by a shift in temperature preferences, but empirical evidence for this is lacking. Here, we test whether exposure to different thermal environments has led to changes in preferred temperatures in the wild. Our study takes advantage of a natural experiment in Iceland, where freshwater populations of threespine sticklebacks (Gasterosteus aculeatus) are found in waters warmed by geothermal activity year-round (warm habitats), adjacent to populations in ambient-temperature lakes (cold habitats). We used a shuttle-box approach to measure temperature preferences of wild-caught sticklebacks from three warm-cold population pairs. Our prediction was that fish from warm habitats would prefer higher water temperatures than those from cold habitats. We found no support for this, as fish from both warm and cold habitats had an average preferred temperature of 13{degrees}C. Thus, our results challenge the assumption that there will be a shift in ectotherm temperature preferences in response to climate change. In addition, since warm-habitat fish can persist at relatively high temperatures despite a lower temperature preference, this suggests that preferred temperature alone may be a poor indicator of a populations adaptive potential to a novel thermal environment.

evolutionary biology↗

bioRxiv2019

Testing the predictability of morphological evolution in naturally warmed stickleback populations

In light of climate change, the ability to predict evolutionary responses to temperature changes is of central importance for conservation efforts. Prior work has focused on exposing model organisms to different temperatures for just one or a few generations under laboratory conditions. Using a natural experiment, we show that studying parallel evolution in wild populations from contrasting thermal environments presents a more powerful approach for understanding and predicting responses to climate change. More specifically, we used a unique study system in Iceland, where freshwater populations of threespine sticklebacks (Gasterosteus aculeatus) are found in waters warmed by geothermal activity, adjacent to populations in ambient-temperature water. We used three sympatric and three allopatric warm-cold population pairs to test for repeated patterns of morphological divergence in relation to thermal habitat. We found that thermal habitat explained over 50% of body shape variation: fish from warm habitats had a deeper mid-body, a shorter jaw, and smaller eyes. Our common garden experiment showed that most of these morphological differences between thermal habitats were heritable. Lastly, absence of gene flow seems to facilitate parallel divergence across thermal habitats: all three allopatric population pairs were on a common evolutionary trajectory, whereas sympatric pairs followed different trajectories. Our findings therefore suggest that morphological responses to rising temperatures can be predictable when there is limited gene flow. On the other hand, migration of individuals between different thermal habitats or microhabitats can exaggerate nonparallel evolution and reduce our ability to predict evolutionary responses.

evolutionary biology↗