Biology subjects

Komdeur, J.

Publications and source records attributed to Komdeur, J..

16 recordsLinked to original sources

bioRxiv2026

Inbreeding depression by polygenic load following a severe population bottleneck

It is poorly understood how populations survive extreme bottlenecks despite severe inbreeding. We investigate the genomic architecture of inbreeding in the once critically endangered Seychelles warbler (Acrocephalus sechellensis) using 37 years of individual-based monitoring and 1.8 million SNPs. Linkage disequilibrium patterns reveal a historical effective population size of [~]270 that plummeted to [~]13 coinciding with human colonisation events of the Seychelles archipelago. Contemporary genomes are over one-third inbred from recent inbreeding measured by runs of homozygosity (ROH) formed since human colonisation of the Seychelles, 50 generations ago (mean FROH < 50 generations ago = 0.38), and we identify significant inbreeding depression across cross key fitness traits. On average, a 17.9% reduction in lifespan and a 15.1% reduction in lifetime offspring production were associated with each 10% increase in individual inbreeding. Genome-wide scans reveal this depression is caused by a polygenic load. Our results suggest that a history of small population size could have facilitated the selective purging of severe genetic load, while mildly deleterious alleles escaped selection via drift. A partitioned genetic load architecture potentially enabled species recovery despite the inbreeding depression that followed near-extinction.

evolutionary biology↗

bioRxiv2026

A Seychelles warbler genomic toolkit

Understanding evolutionary processes is greatly facilitated by high-quality data on genetic variation. We report the development of a genomic toolkit for a recently bottlenecked, long-term studied species, the Seychelles warbler (Ptimerl dezil; Acrocephalus sechellensis). This toolkit comprises a reference genome assembled into 31 chromosomes, together with functional annotations and reference-panel-free imputation of whole-genome sequences from 1,935 individuals. The genomic data have been used to assign the sequenced individuals into a genetic pedigree. Individual genomic data are associated with a suite of phenotypic metadata, amassed from three decades of fieldwork in this closed, long-term monitored population. We compared sex and parentage assigned using the genomic data with the previously recorded sex and parentage metadata to identify and correct 41 sample DNA samples labelled with the wrong identity. This population resource enables a wide range of analyses, that include, but are not limited to phylogenetics, metabarcoding, recombination rates, linkage patterns, adaptation, heritability, demographic history, selection, and inbreeding estimates. We wish to encourage interest from researchers seeking to collaborate on future analyses and data collection. Overall, our methods demonstrate the potential of next generation sequencing and statistical tools to provide dense genomic datasets at large sample sizes for wild populations.

genomics↗

bioRxiv2026

Adaptation to climate driven environments in a Patagonian suboscine passerine

Climate change has altered global climatic conditions, which is affecting the reproductive strategies, offspring development, breeding biology and development of birds. We looked at the impact of different climatic variables (temperature, rainfall and wind speeds) before and during the nestling development phase on nestling development (i.e. nestling hatch weights, nestling growth rates and pre-fledging weights) in the Thorn-tailed Rayadito (Aphrastura spinicauda). We studied two populations. One is situated in a temperate rainforest on the northern border of Patagonia called Pucon which we studied in 2018 and 2019, with mild temperatures (12.5 degrees Celsius), high rainfall (636ml) and low wind speeds (6.3km/h). The other is in a sub-Antarctic old growth forest in southern Patagonia called Navarino island which we studied in 2018, 2019 and 2023, which is comparatively drier (138ml), colder (8.3 degrees Celsius) and has higher average wind speeds (16.6km/h). Embryonic development is key in ensuring individual future fitness. It is important that this is not interrupted and individuals are therefore vulnerable to damage during early development and it can have carry over effects into adulthood. Exposure to extreme climatic conditions can interrupt this development. Therefore, we expect to find that the climate during incubation to be important in predicting nestling hatch weights, growth rates and pre-fledgling weights. Climatic conditions are known to effect nestling development and extremes in climatic conditions have negative consequences on nestling development. We therefore expect that highly variable climatic conditions will have a negative effect on nestling development. We analysed populations separately because we expect populations to have developed different reaction norms to climatic factors. We found in both locations that hatching weights become lower each year, but growth rates and pre-fledging weights are unchanged. In Navarino, medium sized clutches produced the largest hatchlings whilst large and small clutches produced the smallest hatchlings and high or low rainfall during the egg laying and incubation phase produces smaller nestlings. No other climatic factors impacted hatch weights in Navarino. We also found that high or low average ambient temperatures during incubation and early nestling development in Navarino result in lower overall growth rates. Whilst in Pucon, lower rainfall and high or low wind speeds during incubation produce smaller hatchlings, but neither climatic nor biotics factors could explain growth rates in Pucon. We found pre-fledging weights could not be explained by climatic or biotics factors in either location. This is the first study of its kind to examine the environmental drivers of nestling hatch weights in birds in the wild. By better understanding how climate predicts nestling development, we can understand the potential future threats to fitness and development in birds with greater accuracy as conditions continue to change.

developmental biology↗

bioRxiv2026

Climatic conditions predict embryonic development in thorn tailed Rayadito (Aphrastura spinicauda)

Rapid changes to weather caused by climate change have a negative effect on much of the worlds animal populations and species. Some populations are more vulnerable than others to the effects of climate change, and individuals are particularly vulnerable during early development. Good embryonic development is important for vertebrate species because this can dictate their breeding success and survival rates, and disruptions to this phase can have far reaching fitness effects that can last into adulthood and beyond. We looked at the impact of weather (ambient temperature, rainfall and wind speed) on the embryonic development of thorn-tailed Rayadito (Aphrastura spinicauda) at two different latitudes in Patagonia, Chile. We measured the heart rate of embryos just before hatching using an egg buddy machine to determine embryonic development. Optimum development of nestlings is important for fledging, so it is essential that embryonic development is successful. We studied two populations. One is situated in a temperate rainforest on the northern border of Patagonia called Pucon which we studied in 2018 and 2019, with mild temperatures (12 degrees Celsius), high rainfall (636ml) and low wind speeds (6.3km/h). The other is in a sub-Antarctic old growth forest in southern Patagonia called Navarino island which we studied in 2018, 2019 and 2023, which is comparatively drier (138ml), colder (8.3 degrees Celsius) and has higher average wind speeds (16.6km/h). We found that embryonic development was better in the south compared to the north, indicated by higher embryo heart rates near hatching in the south. Development of embryos in the northern site was slower when conditions were cold and windy. Development of embryos in the southern site was unaffected by temperature, rainfall or wind speeds. In northern Patagonia, when minimum temperatures were low and wind speeds high during the period encompassing clutch completion, initiation of full incubation and during incubation, have a negative impact on embryonic development. In contrast, when Rayaditos in the southern population experience slow embryonic development, they extend the incubation period allowing embryos more time to develop before hatching. Our study shows that in the north of Patagonia embryonic development declines over years and that Rayaditos seem not to have adapted to dealing with climate change. On the other hand, in the south of Patagonia, embryonic development is unaffected by climatic factors, suggesting that Rayaditos are adapting to climate change through extending their incubation periods, allowing embryos to fully develop before hatching. It appears that Rayaditos in the northern population are not extending their incubation periods and are not adapting to the threats posed by climate change. To our knowledge, this is the first study of its kind to examine embryonic development in the field and to associate this to changing weather patterns whilst highlighting specific days on which development is influenced.

ecology↗

bioRxiv2025

Life-history traits as predictors of expected genetic contributions 15 years later in a cooperatively breeding bird

An individuals life history plays an important role in how successful individuals are in passing on their genes to future generations. However, exactly which life-history traits best approximate an individuals long-term genetic contributions remains poorly studied, especially in cooperative breeders. Here, we use a genetic pedigree and long-term data of the closed population of the Seychelles warbler (Acrocephalus sechellensis) to calculate the expected individual genetic contributions (IGC) after 15 years (or [~]3 generations) across 11 cohorts. Using a Bayesian analysis we then quantified and compared how well six important life-history traits predict IGC in each sex of this cooperatively breeding species. The life-history traits compared were: acquisition of a dominant breeding position, age at first breeding attempt, tenure as a dominant breeder, lifespan, and LRS (measured as both the number of independent [surviving 3 months+] and recruited [surviving 1 year+] offspring produced over an individuals lifetime). An individuals lifetime reproductive success (LRS) was the strongest predictor of IGC and this predictive power did not differ across the different measurements used. However, this predictive power did differ between sexes, explaining [~]61-62% of IGC variation in males versus [~]47-49% in females owing to the larger variation among males in their annual reproductive success. Across other life-history traits the predictive power of IGC was similar across both sexes but differed between life-history traits considerably (2-37%). Comparing these predictive powers suggested that lifespan and the duration of a dominant breeding position are far more important in shaping long-term genetic contributions than if and when in their life they acquired dominance. Overall, these findings give insight into the individual and population-level processes influencing future gene pools and illustrate how life-history evolution is shaped by sex-specific reproductive patterns and cooperative breeding dynamics.

evolutionary biology↗

bioRxiv2025

Flexible parental care in a songbird correlates with sex-specific responses to seasonal phenology, mating opportunity and reproductive success

O_LISpecies with diverse parental care patterns often exhibit flexibility in response to environmental changes. Such changes can influence parental care decisions by altering the trade-offs between current and future reproduction. While previous studies have revealed correlations between specific social and ecological factors and parental care patterns, the joint effects of multiple factors could be rather complex and may result in different outcomes within and across populations, and between sexes. C_LIO_LIIn this study, we revealed parental care systems and their seasonal variations across three geographic populations in a polygamous species, the Chinese penduline tits (Remiz consobrinus), by monitoring breeding events over years. To investigate how local conditions (including social and ecological conditions) correlate with sex-specific parental care patterns, we compared breeding phenology and local conditions (including season length, mating opportunity and reproductive success) across the populations. C_LIO_LIStriking population differences in parental care strategies are found in this species: biparental care predominated in one population, whereas female-only care was more common in the other two. Our analyses reveal that, despite a large difference in season length, the time of egg-laying peaked similarly across the three populations. Female penduline tits determined the breeding phenology, which varies male mating opportunities dramatically over the season. For all populations, male Chinese penduline tits were more likely to desert the clutch when male mating opportunities were high. In contrast, females consistently provided care, regardless of variation in female mating opportunities. C_LIO_LIWe also found that fitness costs on the current brood resulting from offspring desertion differed across populations. This desertion cost on brood fitness matters more than achieving a high reproductive reward in driving the emergence of uniparental care, contrary to the theory that uniparental care only occurs when single parents can efficiently raise nestlings alone. C_LIO_LIOur study demonstrates that similar parental care patterns across populations could result from different underlying factor interactions and highlights the consistent sex-specific responses to local conditions in parental care. C_LI

ecology↗

bioRxiv2024

Sociality shapes the adaptive response of breeders to harsh thermal environments? An experiment in a burying beetle

O_LIThe rapid pace of environmental change seems to outstrip the evolutionary response rates of many species. Physiological, morphological, and behavioral plasticity alone may also not suffice to cope with environments drastic changes, potentially hindering individuals ability to adapt. Therefore, it has been proposed that social flexibility may be a powerful mechanism for fast adaptation, but empirical evidence is lacking. C_LIO_LIWe investigated the combined effects of manipulated social conditions and ambient temperature during the reproductive phase on parental care, reproductive success, and offspring performance of the burying beetle (Nicrophorus vespilloides), a facultative social breeding insect. C_LIO_LIWe conducted a mixed factorial design experiment, establishing four categories of social conditions during breeding (no-care, unifemale-care, biparenta-care, and multiple-care) alongside two thermal conditions (benign: 20{degrees}C and harsh: 23{degrees}C). Additionally, dispersed larvae produced from each of these breeding conditions were allocated to climate rooms maintained at either 20{degrees}C or 23{degrees}C for pupation. Data on brood size, brood mass, dispersed larval weight, larval development duration, body size and lifespan of newly eclosed beetles, and parental care were collected C_LIO_LIOur results showed that (1) harsh temperature and the without-care condition (i.e., no-care compared to the other three social conditions) reduced brood size, brood mass, body size of newly eclosed beetles; (2) social and ambient thermal conditions had interactive effects on dispersed larval weight, larval development duration, and newly eclosed beetles lifespan; and (3) harsh temperature reduced both individual and total parental care, whereas sociality had opposing effects: individual care decreased, but total care increased from unifemale-care to biparental-care and multiple-care conditions. C_LIO_LIOur findings shed light on the critical role of sociality in modulating the adaptive response of individuals to harsh thermal environments, one of the ecological problems exacerbated by ongoing global warming. C_LI

evolutionary biology↗

bioRxiv2024

Ecological and social factors lead to variation in parental care between sexes in a burying beetle

Sexual conflict over parental care represents a divergence in the evolutionary interests between males and females, consequently leading to distinct sex roles in parental care and reproductive strategies. However, whether and how various ecological and social environments influence such sex differences remains largely unclear. In the present study, using the burying beetles Nicrophorus vespilloides, we experimentally investigated the impacts of resource availability and inter- and intra-specific competition pressure on individual parental care and reproduction in males and females. We manipulated the resource availability for the breeding pairs by providing them with either large or small mouse carcasses, and constructed the presence of intra- and inter-specific competition, by introducing an additional, small pair of beetles and blowfly maggots Calliphora, respectively. We expected that males would decrease their parental care, while females would increase theirs, in response to smaller carcass. We also expected that the presence of intra- and inter-specific competition differentially affected the cares of males and females. We found that, compared to males and females breeding on large carcasses, males did not change their care, whereas females increased their care, when breeding on small carcasses. In the presence of another pair of adults, both males and females increased their parental care, whereas in the presence of blowfly maggots they both decreased their parental care. Our results showed that males and females adjust their parental care based on resource availability and competition pressure, with sex-specific differences driven by ecological and social factors. Our study sheds light on the importance of sex-specific parental care in response to various external drivers which contributes to a better understanding of the evolution of sex conflict over parental care.

animal behavior and cognition↗

bioRxiv2024

A path analysis disentangling determinants of natal dispersal in a cooperatively breeding bird

Delayed offspring dispersal is an important aspect of the evolution of cooperative breeding. By applying a path-analysis approach to the long-term Seychelles warbler (Acrocephalus sechellensis) dataset, we studied whether and how delayed dispersal is affected by territory quality, the presence of helpers and non-helping subordinates, maternal breeding status, age and fecundity, and offspring sex ratio. We found that offspring are more likely to disperse when their genetic mothers are co-breeders, helpers are absent and territory quality is high. In contrast to earlier findings, our analysis does not support the idea that offspring sex ratio is affected by territory quality and helper presence. Our findings suggest that a complex interplay of ecological and social factors shapes dispersal decisions. Our study underscores the importance of considering proximate factors in understanding cooperative breeding dynamics, and it shows that path analyses offer valuable insights into dissecting the intricate relationships influencing dispersal in wild populations.

ecology↗

bioRxiv2023

A major myna problem; invasive predator removal benefits female survival and population growth of a translocated island endemic

Invasive predators are a major driver of extinctions and continue to threaten native populations worldwide. Island eradications of (mostly mammalian) invasive predators have facilitated the (re)establishment of numerous island-endemic populations. Other invasive taxa, such as some predatory birds, could pose a more persistent threat due to their ability to fly and actively re-invade even remote and isolated islands. However, the impact of invasive predatory birds has been largely overlooked. We report on a novel sex-specific impact of an invasive-nest predator, the common myna (Acridotheres tristis), on a reintroduced population of Seychelles warblers (Acrocephalus sechellensis); translocated from Cousin Island to Denis Island in 2004. Regular post-translocation monitoring revealed that female mortality was 20% higher than males, leading to a 60-70% male-biased population sex-ratio between 2005-2015. This was attributed to mynas inflicting severe injuries to incubating female warblers while attempting to prey upon eggs in their nests. These effects likely contributed to the slower-than-expected population growth observed (relative to previous translocations of Seychelles warblers to other islands) over the same period. An eradication programme beginning in 2011 removed all mynas from Denis by 2015. Subsequently, we observed a balancing of sex-specific survival and the population sex-ratio of Seychelles warblers and, consequently, accelerated population growth. This study demonstrates the importance of assessing the threat posed by all invasive taxa (not just mammals) to island conservation. Furthermore, we show how extended monitoring is needed to identify problems, and develop solutions, post-translocation.

ecology↗

bioRxiv2022

Social tolerance as strategy to resolve group conflicts: an experimental study on tug-of-war competition of burying beetles

In animal groups with dominance hierarchies, there often occurs a tug-of-war competition over resources and reproduction between dominants and subordinates, because neither is able to fully control the other. Consequently, individuals may mitigate within-group conflict, either by fighting others or by signalling their willingness to tolerate others. Nevertheless, how such a tolerance interaction evolves remains unclear. Here, we addressed this knowledge gap and tested the tug-of-war competition hypothesis, by investigating whether subordinates pay to stay in the group by helping dominants (pay-to-stay), and whether dominants pay costs by living with subordinates in the group (pay-from-staying). We used the burying beetles, Nicrophorus vespilloides, which compete with intra- and inter-specifics for valuable carcasses that are needed for reproduction. Multiple conspecifics can reproduce together through communal breeding, thereby enhancing benefits in terms of reproduction and resource defence against competitors. In communal associations, larger individuals are often dominant in carcass use and reproduction, whereas subordinates have restricted access to the carcass. Our findings show that cooperative subordinates paid costs by helping dominant breeders in carcass preparation in order to be tolerated (i.e. increased access towards the carcass) by dominant breeders, but subordinates did not increase their reproductive success by helping. Such tolerance was eliminated by a high interspecific competition with blowfly maggots. Our results also show that dominant males, but not dominant females, benefitted more from the presence of subordinates, partly due to a sex difference in the compensation strategy of dominants. Overall, our study demonstrates that a social tolerance occurring in situations with a tug-of-war competition could be a common strategy to resolve conflicts in animal societies.

ecology↗

bioRxiv2022

A life-history perspective on the evolutionary interplay of sex ratios and parental sex roles

Parental care is one of the most diverse social behaviours, and caring by the male, female or both parents is essential for successful reproduction of many organisms. Theoretical and empirical studies suggest that parental sex roles are associated with biased sex ratios. However, there is considerable debate on the causal relationship between parental sex roles and sex ratio biases and on the relative importance of the operational sex ratio (OSR), the adult sex ratio (ASR), and the maturation sex ratio (MSR). Here we use individual-based evolutionary simulations to investigate the joint evolution of sex-specific parental behaviour and the various sex ratios in several life history scenarios. We show that sex differences in maturation time or mortality rates at various life-history stages predict the evolution of parental sex roles relatively well: typically, but not always, parental care is biased toward the sex with the lower mortality or the faster maturation. The association of parental sex roles with the various sex ratios is more intricate. In our simulations, the operational sex ratio at evolutionary equilibrium was typically biased toward the less-caring sex. However, the direction and strength of OSR biases often changed drastically in the course of evolution, implying that, rather than being a driver of parental sex roles, OSR biases emerge as a consequence of sex-biases in parental care. When the MSR or the ASR is biased, this bias is generally associated with a bias in parental care: the overrepresented sex does most of the caring. However, the opposite pattern (that the underrepresented sex did most of the caring) also occurs in some scenarios. Moreover, pronounced parental sex roles may also evolve in the absence of an MSR or ASR bias. Taken together, we conclude that none of the sex ratios can be viewed as drivers of a parental care bias; they rather co-evolve with parental care bias in a subtle manner.

evolutionary biology↗

bioRxiv2022

Putting life history theory to the test - the estimation of reproductive values from field data

Quantifying fitness is important to understand adaptive evolution. Reproductive values are useful for making fitness comparisons involving different categories of individuals, like males and females. By definition, the reproductive value of a category is the expected per capita contribution of the members of that category to the gene pool of future generations. Life history theory reveals how reproductive values can be determined via the estimation of life-history parameters, but this requires intricate algebraic calculations. Recently, a more intuitive, pedigree-based method has become popular, which estimates the genetic contributions of individuals to future generations by tracking their descendants down the pedigree. Here we compare both methods. We implement various life-history scenarios (for which the "true" reproductive values can be calculated) in individual-based simulations, use the simulation data to estimate reproductive values with both methods, and compare the results with the true target values. We show that the pedigree-based estimation of reproductive values is either systematically biased (and hence inaccurate), or very imprecise. This holds even for simple life histories and under idealized conditions. In contrast, the traditional algebraic method estimates reproductive values with high accuracy and precision. Lay SummaryTo study evolution in empirical systems it is important to accurately and precisely measure fitness. Here, using simulations, we compare two methods for estimating fitness and test their accuracy and precision. One estimates life-history parameters and calculates a fitness proxy using complex algebra. The other method estimates genetic contribution to future generations by tracking descendants down the pedigree. We conclude that the pedigree method is unreliable, while the algebraic method is accurate and precise.

evolutionary biology↗

bioRxiv2022

The evolution of ageing in cooperative breeders

Cooperatively breeding animals live longer than their solitary counterparts. The traditional explanation for this is that cooperative breeding evolves more readily in long-lived species. Here, we reverse this argument and show that long lifespans are an evolutionary consequence of cooperative breeding. Natural selection favours a delayed onset of senescence in cooperative breeders, relative to solitary breeders, because cooperative breeders have a delayed age of first reproduction due to reproductive queueing. Especially long lifespans evolve in cooperative breeders with age-dependent reproductive queueing. Finally, we show that lower genetic relatedness among group members leads to the evolution of longer lifespans. This is because selection against higher mortality is weaker when mortality reduces competition between relatives. Our results link the evolutionary theory of ageing with kin selection theory, demonstrating that the evolution of ageing in cooperative breeders is driven by the timing of reproduction and kin structure within breeding territories.

evolutionary biology↗

bioRxiv2020

How do ecological and social environments reflect parental roles in birds? A comparative analysis

Parental roles are highly diverse in animal taxa. Since caring is an important determinant of fitness, understanding the origin and maintenance of various parental care strategies is a key question in evolutionary biology. Here we investigate parental care patterns in birds, which exhibit a remarkable diversity of parental sex roles. By means of phylogenetically informed comparative analyses we investigate whether and how care provisioning is predicted by ecology and social environment. Making use of the most comprehensive dataset including 1101 species that represent 126 avian families, we show that sex differences in parental care are neither related to food type nor to nest type, two key ecological factors. However, we found an effect of the social environment, as males tend to care relatively more in in colonial species than in non-colonial species. Taken together, these results highlight the importance of social effects for evolution of diverse parental sex roles.

evolutionary biology↗

bioRxiv2018

Compensatory and additive helper effects in the cooperatively breeding Seychelles warbler (Acrocephalus sechellensis).

O_LIIn cooperatively breeding species, helper aid may affect dominant breeders investment trade-offs between current and future reproduction. By compensating for the care provided by helpers, breeders can reduce the costs of reproduction and improve chances of survival. Also, helper care can be additive to that of dominants, resulting in higher success of the current brood.\nC_LIO_LIHowever, the influence of helpers on offspring care itself may be the by-product of group size and territory quality. Therefore to make conclusive inferences about causation of additive and compensatory care as a result of help per se requires disentangling the impact of helping from other factors determining parental investment.\nC_LIO_LIIn this study, we use 20 years of offspring provisioning data to investigate the effect of helping on breeder and overall offspring provisioning rates in the facultative cooperatively breeding Seychelles warbler (Acrocephalus sechellensis). Our extensive dataset allowed us to effectively control for the effects of living in a larger group and in territories with higher food availability.\nC_LIO_LIWe show compensatory and additive care in response to helper aid. Helpers lightened the provisioning load of the dominant male and female and increased the total provisioning to the nestlings. This was irrespective of group size or territory quality (food availability).\nC_LIO_LIOur results illustrate how multiple benefits of helping behaviour can simultaneously be fundamental to the evolutionary maintenance of cooperative behaviour.\nC_LI

animal behavior and cognition↗