Survival after arrival: the interplay between selection, dispersal, and connectivity in an intertidal fish

Marine organisms—especially those with planktonic dispersal—have been largely generalised as open systems, with high connectivity and panmixia. While this may be true at a broad scale we know now, however, that this is not necessarily the case and a variety of factors can work together to create population genetic structure at a fine scale. Furthermore, this structure is fluid in space and time, a phenomenon called “chaotic genetic patchiness”.

A lot of work on chaotic genetic patchiness in fish has focused on temperate and tropical reef fish. However, intertidal zone fish provide an excellent system to test hypotheses relating to the nature of population structure: (1) they are easily accessible; (2) patches of suitable rocky shore habitat are flanked by stretches of inhospitable sandy beach, creating a potential dispersal barrier; and (3) the intertidal is a dynamic, challenging environment, where selection is bound to play an important role in population processes.

My PhD uses Cocos frillgoby (Bathygobius cocosensis) as a model for intertidal fish along the east coast of Australia. I aim to address three research objectives that consider: (i) the role of biophysical factors in structuring populations; (ii) the roles of selection versus dispersal on realised connectivity and variable population structure; and (iii) the impact of local selection in creating fine-scale population structure. My methods include the utility of next-generation sequencing and population genomic techniques, otolith analysis, and seascape genetics.