Biology subjects

Vangestel, C.

Publications and source records attributed to Vangestel, C..

4 recordsLinked to original sources

bioRxiv2022

Progressive spread of chromosomal inversions blends the role of colonization and evolution in a parallel Galapagos beetle radiation

Archipelago island fauna include some of the most compelling examples of parallel adaptation to ecological gradients. However, despite the insuslar nature of these systems, the possibility that repeated instances of within-island divergence resulted from independent (in situ) evolutionary rather than repeated colonization events remains most often unclear. Here, we investigated the genomic underpinning of a progressive adaptive radiation of caterpillar-hunter beetles (Calosoma) in the low- and highland habitats from the Galapagos. These Calosoma beetles have evolved only partially reduced wings in the highland of the youngest islands but evolved to distinct short-winged species in the highland of the oldest islands. In support of independent evolutionary events, the extent of genome-wide divergence between long-winged lowland and short-winged highland populations decreased towards younger islands. However, in support of repeated colonization events, adaptation to highland habitats was driven by repeated selection of alleles that are shared across all highland species and populations. These alleles comprised extensive chromosomal inversions whose origin was traced back to an initial high-lowland divergence event on the oldest island. Moreover, we found evidence that after this initial divergence event, highland alleles spread to younger islands through dispersal of highland individuals as well as dispersal of lowland individuals that were polymorphic at adaptive loci, both providing the opportunity for the establishment of highland populations on the younger islands. These findings highlight the importance of an old divergence in driving repeated adaptation to ecological gradients. Complex histories of colonization and introgression may thus result in a mixed contribution of inter-island dispersal and within-island evolution in shaping parallel species communities on islands.

evolutionary biology↗

bioRxiv2022

DNA barcoding echinoderms from the East Coast of South Africa. The challenge to maintain DNA data connected with taxonomy

Echinoderms are marine water invertebrates that are represented by more than 7000 extant species, grouped in five classes and showing diverse morphologies (starfish, sea lilies, feather stars, sea urchins, sea cucumbers, brittle and basket stars). In an effort to further study their diversity, DNA barcodes (DNA fragments of the 5 end of the cytochrome c oxidase subunit I gene, COI) have been used to complement morphological examination in identifying evolutionary lineages. Although divergent clusters of COI sequences were reported to generally match morphological species delineations, they also revealed some discrepancies, suggesting overlooked species, ecophenotypic variation or multiple COI lineages within one species. Here, we sequenced COI fragments of 312 shallow-water echinoderms of the East Coast of South Africa (KwaZulu-Natal Province) and compared morphological identifications with species delimitations obtained with four methods that are exclusively based on COI sequences. We identified a total of 103 morphospecies including 18 that did not exactly match described species. We also report 46 COI sequences that showed large divergences (>5% p-distances) with those available to date and publish the first COI sequences for 30 species. Our analyses also identified discordances between morphological identifications and COI-based species delimitations for a considerable proportion of the morphospecies studied here (49/103). For most of them, further investigation is necessary to keep a sound connection between taxonomy and the growing importance of DNA-based research.

zoology↗

bioRxiv2021

A masculinizing supergene underlies an exaggerated male reproductive morph in a spider.

In many species, individuals can develop into strikingly different morphs, which are determined by a simple Mendelian locus. How selection shapes loci that control complex phenotypic differences remains poorly understood. In the spider Oedothorax gibbosus, males either develop into a hunched morph with conspicuous head structures or as a fast developing flat morph with a female-like appearance. We show that the hunched-differs from the flat-determining allele by a hunch-specific genomic fragment of approximately 3 megabases. This fragment comprises dozens of genes that duplicated from genes found at different chromosomes. All functional duplicates, including doublesex - a key sexual differentiation regulatory gene, show male-specific expression, which illustrates their combined role as a masculinizing supergene. Our findings demonstrate how extensive indel polymorphisms and duplications of regulatory genes may contribute to the evolution of co-adapted gene clusters, sex-limited reproductive morphs, and the enigmatic evolution of exaggerated sexual traits in general.

evolutionary biology↗

bioRxiv2018

Evolution at two time frames: polymorphisms from an ancient singular divergence event fuel contemporary parallel evolution

When species occur in repeated ecologically distinct habitats across their range, adaptation may proceed surprisingly fast and result in parallel evolution. There is increasing evidence that such cases of rapid parallel evolution are fueled by standing genetic variation, but the origin of this genetic variation remains poorly understood. In Pogonus chalceus beetles, short- and long-winged ecotypes have diverged in response to contrasting hydrological regimes and can be repeatedly found along the Atlantic European coast. By analyzing genomic variation across the beetles distribution, we reveal that genomically widespread short-wing selected alleles evolved during a singular divergence event, estimated at ~0.19 Mya. The ancient and differentially selected alleles are currently polymorphic in all populations across the range, allowing for the fast evolution of one ecotype from a small number of random individuals, as low as 5 to 15, of the populations of the other ecotype. Our results suggest that cases of fast parallel ecological divergence might be the result of evolution at two different time frames: divergence in the past, followed by repeated selection on the divergently evolved alleles after admixture. We suggest that this mechanism may be common and potentially further driven by periods of geographic isolation imposed by large-scale environmental changes such as glacial cycles.

evolutionary biology↗