Biology subjects

Barratt, C. D.

Publications and source records attributed to Barratt, C. D..

6 recordsLinked to original sources

bioRxiv2026

A genomic baseline for long-term monitoring of economically important aquatic species in the Netherlands

Aquatic species of economic and ecological importance are increasingly threatened by environmental change, yet their genetic diversity and population structure remain poorly characterised, limiting effective conservation and management. To address this gap, we initiated a multi-species genomic monitoring programme in 2022, targeting key marine and freshwater taxa. A total of 2,420 individuals from 104 locations were sampled across six species: turbot (Scophthalmus maximus), zander (Sander lucioperca), European eel (Anguilla anguilla; both glass eel in the marine environment and adult eel in freshwater environments), blue mussel (Mytilus edulis), flat oyster (Ostrea edulis), and Pacific oyster (Magallana gigas). Using genotyping-by-sequencing (GBS) and SNP arrays, we generated genome-wide SNP datasets to assess population structure, genetic diversity, inbreeding, and relatedness. Among fish species, population structure was generally weak, consistent with high connectivity. However, significant variation in genetic diversity and kinship among localities indicates the presence of distinct source populations that may be critical for maintaining adaptive potential and guiding restoration efforts. In bivalves, cultured populations in the Oosterschelde and Waddenzee were genetically homogeneous, whereas wild populations in Grevelingen and Veerse Meer retained distinct genetic signatures, representing important reservoirs of diversity for conservation and breeding. Together, these results provide a genomic baseline for key aquatic species in the Netherlands and demonstrate the value of coordinated, multi-species genomic monitoring. The identification of genetically distinct and diverse populations offers direct guidance for conservation prioritisation, restoration strategies, and the sustainable management of aquatic genetic resources under ongoing environmental change, in the Netherlands but also applied in other national and transnational monitoring contexts.

evolutionary biology↗

bioRxiv2024

Local genetic adaptation to habitat in wild chimpanzees

How populations adapt to their environment is a fundamental question in biology. Yet we know surprisingly little about this process, especially for endangered species such as non-human great apes. Chimpanzees, our closest living relatives, are particularly interesting because they inhabit diverse habitats, from rainforest to woodland-savannah. Whether genetic adaptation facilitates such habitat diversity remains unknown, despite having wide implications for evolutionary biology and conservation. Using 828 newly generated exomes from wild chimpanzees, we find evidence of fine-scale genetic adaptation to habitat. Notably, adaptation to malaria in forest chimpanzees is mediated by the same genes underlying adaptation to malaria in humans. This work demonstrates the power of non-invasive samples to reveal genetic adaptations in endangered populations and highlights the importance of adaptive genetic diversity for chimpanzees. One-Sentence SummaryChimpanzees show evidence of local genetic adaptation to habitat, particularly to pathogens, such as malaria, in forests.

evolutionary biology↗

bioRxiv2023

Life on the edge: a new toolbox for population-level climate change vulnerability assessments

O_LIGlobal change is impacting biodiversity across all habitats on earth. New selection pressures from changing climatic conditions and other anthropogenic activities are creating heterogeneous ecological and evolutionary responses across many species geographic ranges. Yet we currently lack standardised and reproducible tools to effectively predict the resulting patterns in species vulnerability to declines or range changes. C_LIO_LIWe developed an informatic toolbox that integrates ecological, environmental and genomic data and analyses (environmental dissimilarity, species distribution models, landscape connectivity, neutral and adaptive genetic diversity and genotype-environment associations) to estimate population vulnerability. In our toolbox, functions and data structures are coded in a standardised way so that it is applicable to any species or geographic region where appropriate data are available, for example individual or population sampling and genomic datasets (e.g. RAD-seq, ddRAD-seq, whole genome sequencing data) representing environmental variation across the species geographic range. C_LIO_LIWe apply our toolbox to a georeferenced genomic dataset for the East African spiny reed frog (Afrixalus fornasini) to predict population vulnerability, as well as demonstrating that range loss projections based on adaptive variation can be accurately reproduced using data for two European bat species (Myotis escalerai, and M. crypticus). C_LIO_LIOur framework sets the stage for large scale, multi-species genomic datasets to be leveraged in a novel climate change vulnerability framework to quantify intraspecific differences in genetic diversity, local adaptation, range shifts and population vulnerability based on exposure, sensitivity, and range shift potential. C_LI

evolutionary biology↗

bioRxiv2023

Genomic signatures of past megafrugivore-mediated dispersal in Malagasy palms

O_LISeed dispersal is a key process in the generation and maintenance of genetic diversity and genetic differentiation of plant populations in tropical ecosystems. During the Last Quaternary, most seed-dispersing megafauna was lost globally, but whether this has caused dispersal limitation, loss of genetic diversity, and increased genetic differentiation between plant populations with large, megafaunal fruits (i.e., > 4 cm - megafruits) remains unclear. C_LIO_LIHere, we assessed whether megafrugivore extinctions in Madagascar (e.g., giant lemurs, elephant birds) have affected the genetic diversity and genetic differentiation of four animal-dispersed Malagasy palm (Arecaceae) species with large (Borassus madagascariensis), medium-sized (Hyphaene coriacea, Bismarckia nobilis), and small (Chrysalidocarpus madagascariensis) fruits. We integrated double-digest restriction-site-associated DNA sequencing (ddRAD) of 167 individuals from 25 populations with (past) distribution ranges for extinct and extant seed-dispersing animal species, climate and human impact data, and applied linear mixed-effects models to explore the drivers of variation in genetic diversity and genetic differentiation across Malagasy palm populations. C_LIO_LIWe detected higher genetic diversity in species with megafruits than in the species with small fruits, and genetic differentiation was lowest for the human-used medium-sized megafruit species. Furthermore, we found that a higher number of shared extinct megafrugivore species between palm population pairs was associated with less genetic differentiation, indicating higher gene flow, whereas no relationship with extant frugivores - that are not able to swallow and disperse the seeds - was found. Finally, genetic diversity decreased with road density, whereas genetic differentiation decreased with increasing human population density, but only for populations with megafruits. C_LIO_LIOur results suggest that the legacy of megafrugivores regularly achieving long dispersal distances is still reflected in the genetic diversity and genetic differentiation of palms that were formerly dispersed by such large animals. Furthermore, high genetic diversity and low genetic differentiation were possibly maintained after the megafauna extinctions through human-mediated dispersal, long generation times, and long lifespans of these palms. Our study illustrates how integrating genetics with ecological data on species interactions, climate, and human impact, provides novel insights into the consequences of megafauna extinctions for plants with megafruits. C_LI

evolutionary biology↗

bioRxiv2020

Late Quaternary habitat suitability models for chimpanzees (Pan troglodytes) since the Last Interglacial (120,000 BP)

AimPaleoclimate reconstructions have enhanced our understanding of how past climates may have shaped present-day biodiversity. We hypothesize that habitat stability in historical Afrotropical refugia played a major role in the habitat suitability and persistence of chimpanzees (Pan troglodytes) during the late Quaternary. We aimed to build a dynamic model of changing habitat suitability for chimpanzees at fine spatio-temporal scales to provide a new resource for understanding their ecology, behaviour and evolution. LocationAfrotropics. TaxonChimpanzee (Pan troglodytes), including all four subspecies (P. t. verus, P. t. ellioti, P. t. troglodytes, P. t. schweinfurthii). MethodsWe used downscaled bioclimatic variables representing monthly temperature and precipitation estimates, historical human population density data and an extensive database of georeferenced presence points to infer chimpanzee habitat suitability at 62 paleoclimatic time periods across the Afrotropics based on ensemble species distribution models. We mapped habitat stability over time using an approach that accounts for dispersal between time periods, and compared our modelled stability estimates to existing knowledge of Afrotropical refugia. Our models cover a spatial resolution of 0.0467 degrees (approximately 5.19 km2 grid cells) and a temporal resolution of every 1,000-4,000 years dating back to the Last Interglacial (120,000 BP). ResultsOur results show high habitat stability concordant with known historical forest refugia across Africa, but suggest that their extents are underestimated for chimpanzees. We provide the first fine-grained dynamic map of historical chimpanzee habitat suitability since the Last Interglacial which is suspected to have influenced a number of ecological-evolutionary processes, such as the emergence of complex patterns of behavioural and genetic diversity. Main ConclusionsWe provide a novel resource that can be used to reveal spatio-temporally explicit insights into the role of refugia in determining chimpanzee behavioural, ecological and genetic diversity. This methodology can be applied to other taxonomic groups and geographic areas where sufficient data are available.

ecology↗

bioRxiv2018

Sexual Dichromatism Drives Diversification Within a Major Radiation of African Amphibians

Theory predicts that sexually dimorphic traits under strong sexual selection, particularly those involved with intersexual signaling, can accelerate speciation and produce bursts of diversification. Sexual dichromatism (sexual dimorphism in color) is widely used as a proxy for sexual selection and is associated with rapid diversification in several animal groups, yet studies using phylogenetic comparative methods to explicitly test for an association between sexual dichromatism and diversification have produced conflicting results. Sexual dichromatism is rare in frogs, but it is both striking and prevalent in African reed frogs, a major component of the diverse frog radiation termed Afrobatrachia. In contrast to most other vertebrates, reed frogs display female-biased dichromatism in which females undergo color transformation, often resulting in more ornate coloration in females than in males. We produce a robust phylogeny of Afrobrachia to investigate the evolutionary origins of sexual dichromatism in this radiation and examine whether the presence of dichromatism is associated with increased rates of net diversification. We find that sexual dichromatism evolved once within hyperoliids and was followed by numerous independent reversals to monochromatism. We detect significant diversification rate heterogeneity in Afrobatrachia and find that sexually dichromatic lineages have double the average net diversification rate of monochromatic lineages. By conducting trait simulations on our empirical phylogeny, we demonstrate our inference of trait-dependent diversification is robust. Although sexual dichromatism in hyperoliid frogs is linked to their rapid diversification and supports macroevolutionary predictions of speciation by sexual selection, the function of dichromatism in reed frogs remains unclear. We propose that reed frogs are a compelling system for studying the roles of natural and sexual selection on the evolution of sexual dichromatism across both micro- and macroevolutionary timescales.

evolutionary biology↗