Why are intertidal fishes prone to amphibious behaviour?

Presented by Elizabeth Surovic

PhD Candidate, University of NSW

Supervisors: Associate Prof Terry Ord (UNSW), Prof Paul Gribben (UNSW)

Does entering a new environment encourage adaptive change, or do certain species’ exaptations help them succeed in diversifying into new environments? Family Blenniidae is a group of small, cryptic, benthic tropical fish with species in all three stages of the water-to-land transition: aquatic, amphibious, and terrestrial. The intertidal regions of tropical islands in the Pacific and Indian Oceans are home to a large population of blennies. With tides rising and falling, temperatures, oxygen levels, and resources are constantly changing in these intertidal zones. This offers a rare chance to investigate whether these fish use facilitated adaptive change when they move to land or if they have exaptations that make the move easier.

This study measured various morphological characteristics that were anticipated to be important for shifting from water to land in 72 species. It also includes a series of phylogenetic analyses, aiming to find exaptive traits and traits that have evolved due to land colonisation. This study not only looks at general adaptive habitat transitions but, more specifically, at how fish make such drastic transitions. This can relate back to the early Devonian transition and give scientists a new outlook on exaptations and adaptive change during that time.