My research interest lies in trait evolution both at macroevolutionary (comparative phylogenetics) and microevolutionary (experimental biology and transcriptomics) scales. My work is strongly focused (though not exclusively) on life history traits in amphibians with geographic ties to Africa and southeastern Europe.
Molecular Phylogenetics and Lineage Diversification
Understanding how organisms are related to each other is a central aspect of my research. Reconstructing fossil-calibrated molecular phylogenies (chronograms underpins our understanding of biogeographic patterns, trait evolution and lineage diversification. A major theme of my research has been to understand how species of African toads (family Bufonidae) have accumulated since their arrival on the continent some 20-30 million years ago.
Studying the patterns of lineage splitting on phylogenies can tell us a lot about how present diversity has arisen. For example, species colonizing new geographic areas are thought to be presented with an ‘Ecological Opportunity' to adapt and diversify into vacant niche-space. Indeed, a number of studies show that species take advantage of a competitor-free landscape on islands or insular systems and speciate at high rates until a saturation point is reached, at which point diversification rates stabilize in a diversity-dependent fashion. Whether the same patterns exist for continental radiations is less clear and does not seem to be the case for African toads.
Genome Size Evolution in Amphibians
Genomes of different organisms vary hugely in size. Most of this difference is not linked to organism complexity, but instead, in the amount of non-coding DNA. Whether or not life history traits affect the evolution of the physical size of genomes is unclear. On a cellular level, large genomes impose physiological rate limits and processes like cell proliferation and differentiation are significantly slower. This is particularly important for amphibians, which have some of the largest genomes of all known vertebrates and many undergo complex life history transitions that involve both rapid growth as well as cell and tissue differentiation. Using this interesting model system, we uncover some of the delicate interplays that might be shaping the evolution of genome size.
Developmental Plasticity in Pelobates cultripes
Developmental plasticity is a common adaptation to environmental heterogeneity and understanding the evolution of such plasticity is an important goal in evolutionary biology. Amphibian larvae are usually capable of accelerating their development in response to pond drying to avoid desiccation risk, with the Western Spadefoot toad (Pelobates cultripes) being an extreme example. This species can accelerate its development by more than 30%! The Gomez Mestre Group is currently working on uncovering the epigenetic network underlying this plasticity, by experimentally induce early development through simulated pond drying and screen the genome for nucleosome eviction and changes in methylation patterns, both of which are known epigenetic mechanisms.
African Amphibian Systematics and Natural History
A great deal of work needs to be done to update the taxonomy and systematics of African amphibians and to gain a deeper understanding about aspects of their natural history. Recent years, perhaps fueled by the proliferation of molecular barcoding techniques coupled with phylogenetic and coalescence species delimitation methods, have seen a surge in systematic revisions and newly described species. Together with many colleagues, I have contributed to furthering our understanding of species, their distributions and tadpole morphology for a number of African amphibians. Follow some of these stories here: