Biology subjects

Rasteiro, R.

Publications and source records attributed to Rasteiro, R..

4 recordsLinked to original sources

bioRxiv2024

Life history traits influence the dynamics of genetic diversityin a refugium population undergoing expansion andcontraction

Species ranges are dynamic, experiencing expansions, contractions or shifts as a response to habitat changes induced by extrinsic factors such as climate change and, more recently, human activities. While the scientific literature has explored the genetic effects of spatial processes, published studies rarely incorporate life-history traits to study the effect of such changes on species living in the same environments. There is thus a gap in our understanding regarding the variation in genetic diversity patterns among species with distinct life-history traits such as growth rates and generation times, experiencing the same habitat change scenarios. In this study, we first used spatial simulations to investigate the temporal dynamics of genetic diversity within refugium populations experiencing a range expansion followed by a stationary and a contraction period. We explored different scenarios, varying both the speed of contraction and the life-history traits of the simulated species. In addition, we used a simpler panmictic model for which we derived analytical results. Altogether, we identified three temporal dynamics of genetic diversity in the refugium population during the contraction phase: scenarios where genetic diversity i) decreased throughout the contractions, ii) increased for periods that could be greater than thousands of years before plateauing and then decreasing or iii) followed a persistent increasing trend, without any visible effect of the expansion or contraction. We show that these different temporal dynamics can be predicted by comparing the observed expected heterozygosity (He) to the values expected if the species were at equilibrium within the refuge (He refuge) and within the whole landscape (He landscape). We also observe that there are scenarios where a rapid contraction maintains more diversity just at the end of the contraction, as widely believed and as reported in a previous simulation study. However, we also observe the opposite pattern for a wide range of parameters. The widespread idea that observing high diversity levels in a refugium population is due to a recent and rapid habitat loss is thus not necessarily true and will depend on various life history traits and how they relate to habitat change dynamics.

evolutionary biology↗

bioRxiv2022

The effect of habitat loss and fragmentation on isolation-by-distance and time

Throughout Earths natural history, habitats have undergone drastic changes in quality and extent, influencing the distribution of species and their diversity. In the last few hundred years, human activities have destroyed natural habitats at an unprecedent rate, converting continuous habitat into fragmented and isolated patches. Recent global metanalyses suggest that habitat loss and fragmentation (HL&F) has negatively impacted the genetic diversity of many taxa across the world. These conclusions have been drawn by comparing present-day genetic patterns from populations occurring in continuous and fragmented landscapes. In this work, we attempted to go beyond pattern and investigate through simulations some of the processes that influence genetic variation in the context of HL&F. Since most species have a geographically restricted dispersal (known as "isolation-by-distance", IBD), we studied the impact of HL&F on isolation-by-distance. We characterised the behaviour of IBD in the case of i) instantaneous HL&F, ii) gradual (two-steps) HL&F, and iii) instantaneous HL&F following range expansion. In addition, we propose a spatially-explicit theoretical framework by modifying the original theoretical results on isolation-by-distance (Slatkin, 1991; Slatkin, 1993) and apply them to a toroidal stepping-stone model in the context of HL&F. Our results suggest that isolation-by-distance can be maintained for relatively long time after HL&F, thus pointing to the long-term importance of spatial genetic structure in species genetic diversity. In addition, our results may explain why present-day fragmented population still show significant IBD pattern although being disconnected.

evolutionary biology↗

bioRxiv2022

On the genetic consequences of habitat contraction: edge effects and habitat loss

Natural climate change and recent anthropogenic activities have largely contributed to habitat loss and fragmentation across the world, leading to 70% of worldwide remaining forests to be within 1 km of forests edges (Haddad et al., 2015). Ecological studies have shown that edge-effect influences ecological communities, species richness and abundance across many taxa, contributing to worldwide decline in biodiversity. Since edge-effect reduces species abundance and connectivity, it is also expected to negatively influence species genetic variation. In fact, previous theoretical studies had showed that populations closer to the edges of a finite stepping-stone model tends to have shorter coalescence times, and therefore, lower genetic diversity, than central populations. However, predicting the impact of edge effect on local genetic diversity remains challenging in realistic and more complex habitat fragments, where the additive effect of multiple edges is expected to take place. In the present study we explore the genetic consequence of habitat loss at the scale of a habitat fragment (patch-scale), looking at the interplay between patch-size and edge-effect on spatial genetic diversity. We propose a statistical approach to estimate edge-impacted effective population size from habitat cover information and use this measure to predict spatial genetic diversity in both equilibrium and non-equilibrium populations. We address these questions using spatially-explicit simulations and propose a spatially-explicit analytical framework able to model spatio-temporal changes in genetic diversity due to edge-effect and habitat loss.

evolutionary biology↗

bioRxiv2018

Evolution of the CLTCL1 Gene Encoding CHC22 Clathrin Reveals Selection Influencing CHC22’s Role in Human Glucose Metabolism

CHC22 clathrin plays a key role in intracellular membrane traffic of the insulin-responsive glucose transporter GLUT4 in humans. We performed population genetic and phylogenetic analyses of the CHC22-encoding CLTCL1 gene, revealing independent gene loss in at least two vertebrate lineages, after arising from gene duplication. All vertebrates retained the paralogous CLTC gene encoding CHC17 clathrin, which mediates endocytosis. For vertebrates retaining CLTCL1, strong evidence for purifying selection supports CHC22 functionality. All human populations maintained two high frequency CLTCL1 allelic variants, encoding either methionine or valine at position 1316. Functional studies indicated that CHC22-V1316, which is more frequent in farming populations than in hunter-gatherers, has different cellular dynamics than M1316-CHC22 and is less effective at controlling GLUT4 membrane traffic, attenuating its insulin-regulated response. These analyses suggest that ancestral human dietary change influenced selection of allotypes that affect CHC22s role in metabolism and have potential to differentially influence the human insulin response.

genetics↗