Biology subjects

Paijmans, A. J.

Publications and source records attributed to Paijmans, A. J..

7 recordsLinked to original sources

bioRxiv2026

Early-life environmental conditions shape demographic responses to climate change in male Antarctic fur seals

Climate change intensifies selection, driving population declines and eroding genetic diversity, yet the mechanisms linking environmental perturbations to long-term demographic and evolutionary outcomes remain elusive. In particular, deteriorating early-life environments can have lasting impacts on fitness and population dynamics, but detecting these carry-over effects requires multidecadal, individual-based datasets. Long-term monitoring of Antarctic fur seals at Bird Island, South Georgia, has revealed a decline in breeding female numbers associated with persistent positive phases of the Southern Annular Mode (SAM), when warmer sea surface temperatures reduce local krill abundance. However, male responses remain understudied as their large size and aggressiveness preclude conventional tagging. To investigate male population dynamics, we combined 27 years of field observations of nearly 2,000 individually paint-marked territorial males with genetic recapture analysis of over 11,000 tissue samples, testing for both direct effects of the SAM on male abundance and lagged effects operating through recruitment. Territorial male numbers declined by 61%, yet male abundance was decoupled from the contemporary SAM, reflecting a delayed recruitment strategy that allows resource accumulation over multiple years and buffers short-term environmental variation. By contrast, recruitment probability fell by 59% annually and was strongly linked to natal conditions. Males born during increasingly positive SAM phases were significantly less likely to recruit, whereas heavier and more heterozygous individuals showed higher recruitment success, indicating that adverse natal environments act as selective filters. These findings identify a pathway linking environmental variability to population decline through recruitment dynamics, highlighting the importance of accounting for early-life carry-over effects when predicting the resilience of long-lived species to rapid environmental change.

ecology↗

bioRxiv2024

Sustainability in the laboratory: evaluating the reuseability of microtiter plates for PCR and fragment detection

1.Single-use plastics (SUPs) are indispensable in laboratory research, but their disposal contributes substantially to environmental pollution. Consequently, reusing common SUP items such as microtiter plates represents a promising strategy for improving laboratory sustainability. However, the key challenge lies in determining whether SUP reuse can be implemented without sacrificing data quality. To investigate this, we conducted a simple experiment to assess the impact of reusing microtiter plates on microsatellite genotyping accuracy. Plates previously used for PCR and fragment detection were cleaned opting for an environmentally friendly approach using regular soap and then reused. Our results indicate that, while reusing PCR plates significantly increases genotyping error rates due to residual DNA contamination, detection plates can be reused without compromising data quality. Our approach offers laboratories a practical and sustainable option for reducing SUP waste and costs while maintaining research integrity.

molecular biology↗

bioRxiv2024

Little evidence for inbreeding depression for birth mass, survival and growth in Antarctic fur seal pups

Inbreeding depression, the loss of offspring fitness due to consanguineous mating, is generally detrimental for individual performance and population viability. We therefore investigated inbreeding effects in a declining population of Antarctic fur seals at Bird Island, South Georgia. Here, localised warming has reduced the availability of the seals staple diet, Antarctic krill, leading to a temporal increase in the strength of viability selection against inbred offspring, which are increasingly failing to recruit into the adult breeding population. However, it remains unclear whether viability selection operates before or after nutritional independence at weaning. We therefore used microsatellite data from 884 pups and their mothers, and SNP array data from 100 mother-offspring pairs, to quantify the effects of individual and maternal inbreeding on three important neonatal fitness traits: birth mass, survival and growth. We did not find any clear or consistent effects of inbreeding on any of these traits. This suggests that viability selection filters inbred individuals out of the population as juveniles during the time window between weaning and recruitment. Our study brings into focus a poorly understood life-history stage and emphasises the importance of understanding the ecology and threats facing juvenile pinnipeds.

evolutionary biology↗

bioRxiv2021

Low heritability and high phenotypic plasticity of salivary cortisol in response to environmental heterogeneity in fur seals

Individuals are unique in how they interact with and respond to their environment. Correspondingly, unpredictable challenges or environmental stressors often produce an individualized response of the hypothalamic-pituitary-adrenal axis and its downstream effector cortisol. We used a fully crossed, repeated measures design to investigate the factors shaping individual variation in baseline cortisol in Antarctic fur seal pups and their mothers. Saliva samples were collected from focal individuals at two breeding colonies, one with low and the other with high density, during two consecutive years of contrasting food availability. Mothers and pups were sampled concurrently at birth and shortly before weaning, while pups were additionally sampled every 20 days. We found that heritability was low for baseline cortisol, while within-individual repeatability and among-individual variability were high. A substantial proportion of the variation in baseline cortisol could be explained in pups and mothers by a combination of intrinsic and extrinsic factors including sex, weight, day, season, and colony of birth. Our findings provide detailed insights into the individualization of endocrine phenotypes and their genetic and environmental drivers in a wild pinniped. Furthermore, the strong associations between cortisol and life history traits that we report in fur seals could have important implications for understanding the population dynamics of species impacted by environmental change.

ecology↗

bioRxiv2021

Where are the beachmasters? Unexpectedly weak polygyny among southern elephant seals on a South Shetland Island

Intraspecific variation in animal mating systems can have important implications for ecological, evolutionary and demographic processes in wild populations. For example, patterns of mating can impact social structure, dispersal, effective population size and inbreeding. However, few species have been studied in sufficient detail to elucidate mating system plasticity and its dependence on ecological and demographic factors. Southern elephant seals (Mirounga leonina) have long been regarded as a textbook example of a polygynous mating system, with dominant beachmaster males controlling harems of up to several hundred females. However, behavioural and genetic studies have uncovered appreciable geographic variation in the strength of polygyny among elephant seal populations. We therefore used molecular parentage analysis to investigate patterns of parentage in a small satellite colony of elephant seals at the South Shetland Islands. We hypothesised that dominant males would be able to successfully monopolise the relatively small numbers of females present in the colony, leading to relatively high levels of polygyny. A total of 424 individuals (comprising 33 adult males, 101 adult females and 290 pups) sampled over eight years were genotyped at 20 microsatellites and reproductive success was analysed by genetically assigning parents. Paternity could only be assigned to 31 out of 290 pups (10.7%), despite our panel of genetic markers being highly informative and the genotyping error rate being very low. The strength of inferred polygyny was weak in comparison to previous genetic studies of the same species, with the most successful male fathering only seven pups over the entire course of the study. Our results show that, even in a species long regarded as a model for extreme polygyny, male reproductive skew can vary substantially among populations.

animal behavior and cognition↗

bioRxiv2020

A 90K SNP array uncovers inbreeding and cryptic relatedness in an Antarctic fur seal breeding colony

High density single nucleotide polymorphism (SNP) arrays allow large numbers of individuals to be rapidly and cost-effectively genotyped at large numbers of genetic markers. However, despite being widely used in studies of humans and domesticated plants and animals, SNP arrays are lacking for most wild organisms. We developed a custom 90K Affymetrix Axiom array for an intensively studied pinniped, the Antarctic fur seal (Arctocephalus gazella). SNPs were discovered from a combination of genomic and transcriptomic resources and filtered according to strict criteria. Out of a total of 85,359 SNPs tiled on the array, 75,601 (88.6%) successfully converted and were polymorphic in 274 animals from a breeding colony at Bird Island in South Georgia. Evidence was found for inbreeding, with three genomic inbreeding coefficients being strongly intercorrelated and the proportion of the genome in ROH being non-zero in all individuals. Furthermore, analysis of genomic relatedness coefficients identified multiple second and third order relatives among a sample of ostensibly unrelated individuals. Such "cryptic relatedness" within fur seal breeding colonies may increase the likelihood of consanguinous matings and could therefore have implications for understanding fitness variation and mate choice. Finally, we demonstrate the cross-amplification potential of the array in three related species. Overall, our SNP array will facilitate future studies of Antarctic fur seals and has the potential to serve as a more general resource for the wider pinniped research community.

evolutionary biology↗

bioRxiv2018

Recent demographic histories and genetic diversity across pinnipeds are shaped by anthropogenic interactions and mediated by ecology and life-history

A central paradigm in conservation biology is that population bottlenecks reduce genetic diversity and negatively impact population viability and adaptive potential. In an era of unprecedented biodiversity loss and climate change, understanding both the determinants and consequences of bottlenecks in wild populations is therefore an increasingly important challenge. However, as most studies have focused on single species, the multitude of potential drivers and the consequences of bottlenecks remain elusive. Here, we used a comparative approach by integrating genetic data from over 11,000 individuals of 30 pinniped species with demographic, ecological and life history data to elucidate the consequences of large-scale commercial exploitation by 18th and 19th century sealers. We show that around one third of these species exhibit strong genetic signatures of recent population declines, with estimated bottleneck effective population sizes reflecting just a few tens of surviving individuals in the most extreme cases. Bottleneck strength was strongly associated with both breeding habitat and mating system variation, and together with global abundance explained a large proportion of the variation in genetic diversity across species. Overall, there was no relationship between bottleneck intensity and IUCN status, although three of the four most heavily bottlenecked species are currently endangered. Our study reveals an unforeseen interplay between anthropogenic exploitation, ecology, life history and demographic declines, sheds new light on the determinants of genetic diversity, and is consistent with the notion that both genetic and demographic factors influence population viability.

evolutionary biology↗