A PhD Journey

You are what you eat, and the same applies for coral reef fishes. These fishes constitute one of the most diverse vertebrate assemblages on Earth, spanning a broad range of dietary strategies. But would it be possible that fish diets could influence their evolution and, as a consequence, their diversity? This was the main question of my PhD thesis, in which I combined information from fossils, DNA, geographical distributions and ecology to understand the evolution of trophic groups in coral reef fishes from multiple viewpoints. First, I showed that evolutionary trophic innovations (i.e., the rise of new dietary strategies) are closely related to the rate at which new reef fish species originate. Relative to all other trophic groups, herbivores diversified remarkably fast, a pattern that is particularly pronounced in larger species. Second, I found a unique trophic link in coral reef fish diversity patterns. Planktivores are far more diverse within the global marine biodiversity hotspot – disproportionally so when compared to other dietary groups. Finally, I focused on herbivorous species to describe their large-scale biogeographical patterns. This analysis revealed historic geological events as critical drivers of the global composition of reef fish herbivores. In conjunction, the results of my thesis highlight historical contingencies and the evolution of novel trophic strategies as major determinants of present-day distribution patterns in coral reef fishes.

The journey throughout these discoveries was extremely rewarding, although quite unusual for the typical marine biologist. Usually, people picture marine biologists as fortunate humans that get to spend most of their time underwater in tropical islands studying fascinating living creatures. In fact, we tend to be fortunate people for being able to work with what we love. But the tropical paradise stereotype represents more of an exception than a rule amongst us, which was also my case. My PhD thesis was entirely developed based on data that was already available in public repositories, so most of my time was spent finding, cleaning, curating, and finally analysing data. This is certainly not a complaint from my part, because even though I would have loved to spend time on tropical islands, I feel like I learnt essential skills for becoming a scientist.

Another fundamental part of my personal journey was the opportunity to be part of a very collaborative and supportive research group. Science is a collective endeavour and being able to share my thoughts, doubts and achievements during long coffee-break sessions with my colleagues was essential to keep me on track and motivated. Today, I am lucky enough to keep working within the same research group in a postdoctoral position, diving deeper into the fascinating world of coral reef evolution. Although challenging at times, this is a fulfilling path that will hopefully lead me to my ultimate goal of becoming a university lecturer.

Originally published in the James Cook University GRS Update April 2021.