What Darwin couldn't see: Island formation and historical sea levels shape genetic divergence and island biogeography in a coastal marine species

Oceanic islands play a central role in the study of evolution and island biogeography. The Galapagos Islands are one of the most studied oceanic archipelagos but research has almost exclusively focused on terrestrial organisms compared to marine species. Here we used the Galapagos bullhead shark (Heterodontus quoyi) and single nucleotide polymorphisms (SNPs) to examine evolutionary processes and their consequences for genetic divergence and island biogeography in a shallow-water marine species without larval dispersal. The sequential separation of individual islands from a central island cluster gradually established different ocean depths between islands that pose barriers to dispersal in H. quoyi. Isolation-by-resistance analysis suggested that ocean bathymetry and historical sea level fluctuations modified genetic connectivity. These processes resulted in at least three genetic clusters that exhibit low genetic diversity and effective population sizes that scale with island size and ..., Tissue samples were collected from Galapagos bullhead sharks from six islands in the Galapagos archipelago and stored in 96% EtOH.
DNA extraction, sequencing and SNP genotyping were conducted by Diversity Array Technologies (DArT, Canberra, Australia). Samples were processed using the proprietary DArT Pty Ltd analytical pipeline, which includes technical replicates from a subset of samples to assess genotyping reproducibility., R software
Packages:

radiator: https://thierrygosselin.github.io/radiator/

DartR: http://georges.biomatix.org/dartR