Uncovering endemism in a lake of invasive species introgression.
In this issue of Molecular Ecology, Blackwell et al. (2020) explored the history of divergence and admixture between the highly invasive Nile tilapia, Oreochromis niloticus, and a recently discovered Oreochromis lineage that is endemic to the coastal lakes of southern Tanzania. Combining microsatellite genotyping and whole genome resequencing with morphological analyses, Blackwell et al. (2020) show that southern populations of Oreochromis korogwe within lakes Rutamba, Nambawala and Mitupa are genetically distinct from allopatric O. korogwe populations in northern Tanzania, as well as other Oreochromis congeners studied within the region. Blackwell et al. (2020) provide evidence that recent introductions of invasive Nile tilapia, O. niloticus, into isolated southern watersheds have resulted in repeated hybridisation with endemic O. korogwe populations at various degrees among sampled lakes. The study by Blackwell et al. (2020) illustrates how genomic data from few sampled individuals can uncover endemic lineages at risk of losing diversity and provides a first glimpse of how anthropogenic hybridisation has shaped their evolution.