Research Projects

Understanding how species rapidly evolve variations in traits like body size, which are controlled by many genes, is critical to the core of genetics. Body size is a polygenic trait, influenced by at least a hundred genes, and evolves under various ecological factors, such as life history traits and competition. Despite its importance, the genetic basis of body size variation remains poorly understood. It is expected that traits like body size will vary across genera over time as differences accumulate in the genome. However, closely related species with extreme trait variation might evolve by accumulating changes in specific genomic regions, while the rest of the genome remains relatively conserved. This creates opportunities to better distinguish the genetic mechanisms involved. In this study, we aim to explore the genetic basis of body size divergence in monitor lizards (Varanus spp.), which exhibit a wide range of body sizes, from the 25 cm short-tailed pygmy monitor to the 3-meter-long Komodo dragon. These species provide a model for studying body size evolution in the wild. We seek to test whether extreme variation in body size in monitor lizards arises from: (a) epigenetic modifications like DNA methylation, (b) changes in protein and regulatory RNA sequences through point mutations, (c) gene duplications affecting dosage, or (d) genomic rearrangements altering gene regulation. We hypothesize that closely related species may evolve size differences primarily through epigenetic changes and point mutations (a and b), while more distantly related species might experience changes across multiple genomic mechanisms (a-d). To investigate these hypotheses, we will assemble whole genomes of at least 20 monitor lizard species, categorized by body size (small, medium, large), using long-read PacBio sequencing technology. The genome assemblies will be annotated with RNA sequencing data, and gene duplications and predictions will be assessed. We will overlay DNA methylation data from PacBio reads onto these annotations. Using candidate genes linked to body size, we will examine mutation rates in closely and distantly related species, accounting for environmental variables obtained from iNaturalist and GBIF databases, as well as bioclimatic factors. A pairwise syntenic analysis will be performed between species to identify conserved and divergent genomic regions. By correlating phenotypic changes (body size) with genomic alterations, we aim to understand how specific genetic changes contribute to body size variation. The findings from this study will provide valuable insights into the genetic basis of body size evolution and polygenic traits more broadly. We will explore how large phenotypic changes can arise rapidly, offering potential for discovering novel genomic regions, both coding and non-coding, that regulate body size. This research may also trigger conservation genetic studies, particularly for endangered or data-deficient species.