The genomic origin of species: a comparative study in the Australian Meliphagoidea
A project undertaken at CSIRO National Research Collections Australia and supervised by Leo Joseph
Unraveling the mechanisms underlying the process of speciation has been pursuit of evolutionary biologists since Darwin. The rich continental-scale Australian vertebrate biodiversity provides a powerful framework to take a comparative approach in studying this process. Although it takes millions of years for speciation to complete, many pairs of populations are currently exists at different stages of this trajectory: incipient species. This provides the perfect setting to study how incompatibilities accumulate between populations through time to the point where they may be considered full species. Understanding the process of speciation provides insight on how different factors influence species formation and, ultimately, how biodiversity has, and will be, formed.
Conveniently, the speciation process can leave footprints throughout the genome. By observing the movement of genomic regions between incipient species pairs at different stages of speciation, we will understand the accumulation of barriers to gene flow. The project will focus 13 incipient species pairs within the avian group meliphagoidea; comprising of fairywrens, honeyeaters, pardalotes, etc. The focal pairs have a shared zone of contact in northern Queensland, dividing the Cape York and central Queensland populations. To compliment the genomic data, morphology and plumage data will be collected to understand the interplay between genomic and phenotypic differentiation. Taking an intrinsic (genomic) and extrinsic (phenotypic) perspective provides an integrative approach to studying the process of speciation in an iconic Australian avian group.
Initial results have shown wide variation in genetic divergence and genetic exchange between bird populations from the Cape York Peninsula and central Queensland. This region in Australia is an example where many populations at various stages of speciation co-occur. Sampling throughout the region has also showed that genetic exchange between some populations are localized while others are geographically broad and rampant. This sets up further questions regarding the interplay between the external environment and intrinsic genetic incompatibilities and how it influences variation in gene exchange throughout the genome. Also, by developing a high quality genome of the Superb Fairy-wren, we have a genomic resource to apply to all Meliphagoidea and so understand the genetic shifts in speciation right down to the level of which genes are most affected.
Peñalba, J. V., Mason, I. J., Schodde, R., Moritz, C., & Joseph, L. Characterizing divergence through three adjacent Australian avian transition zones. Journal of Biogeography. 2017;00:1–12. https://doi.org/10.1111/jbi.13048