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Adam D Leaché

Publications and source records attributed to Adam D Leaché.

3 recordsLinked to original sources
PubMed2026

The evolutionary origins of the parthenogenetic lizard Aspidoscelis tesselatus.

Most vertebrate species reproduce sexually. The whiptail lizards (Aspidoscelis) are a notable exception; at least 11 of the 45 recognized species are parthenogenetic. Here, we focus on one such species (Aspidoscelis tesselatus) as a case study to understand how parthenogenetic species originate and evolve. Using genome-wide sequence data and ecological niche modelling, we find that A. tesselatus likely arose from a single hybrid speciation event between A. scalaris and A. marmoratus less than 500,000 years ago. The geographic ranges of A. tesselatus and its parental species overlap currently, and niche modelling shows this zone of sympatry was even broader during the period when A. tesselatus likely formed. We additionally show evidence that A. tesselatus has a dynamic genome post-formation, with de novo mutations, introgression, and double-strand break associated events all contributing to variation within the species. These results show that asexual lineages can continue to be shaped by ongoing genomic and ecological dynamics, illuminating the processes that influence transitions in reproductive mode.

asexuality↗
PubMed2025

Ancient Introgression Explains Mitochondrial Genome Capture and Mitonuclear Discordance Among South American Collared Tropidurus Lizards.

Mitonuclear discordance-evolutionary discrepancies between mitochondrial and nuclear DNA phylogenies-can arise from various factors, including introgression, incomplete lineage sorting, recent or ancient demographic fluctuations, sex-biased dispersal asymmetries, among others. Understanding this phenomenon is crucial for accurately reconstructing evolutionary histories, as failing to account for discordance can lead to misinterpretations of species boundaries, phylogenetic relationships, and historical biogeographic patterns. We investigate the evolutionary drivers of mitonuclear discordance in the Tropidurus spinulosus species group, which contains nine species of lizards inhabiting open tropical and subtropical environments in South America. Using a combination of population genetic and phylogenomic approaches applied to mitochondrial and nuclear data, we identified different instances of gene flow that occurred in ancestral lineages of extant species. Our results point to a complex evolutionary history marked by prolonged isolation between species, demographic fluctuations, and potential episodes of secondary contact with genetic admixture. These conditions likely facilitated mitochondrial genome capture while diluting signals of nuclear introgression. Furthermore, we found no strong evidence supporting incomplete lineage sorting or natural selection as primary drivers of the observed mitonuclear discordance. Therefore, the unveiled patterns are most consistent with neutral demographic processes, coupled with ancient mitochondrial introgression, as the main factors underlying the mismatch between nuclear and mitochondrial phylogenies in this system. Future research could further explore the role of other demographic processes, such as asymmetric sex-biased dispersal, in shaping these complex evolutionary patterns.

Animals↗