PhD Project Overview

Notothenioid fishes, which dominate the species diversity, abundance, and biomass of the Antarctic continental shelf ichthyofauna, are an iconic example of adaptive radiation in an extreme marine environment. Interestingly, however, one of the most species-rich notothenioid subclades occurs almost entirely outside of Antarctic waters. Patagonotothen comprises ~15 species distributed in marine habitats around southern South America and the Falkland Islands. Only one species, Patagonotothen guntheri, has a distribution that extends south of the Antarctic Polar Front. Given their high species richness and recent evolutionary origin (3-6 Ma), Patagonotothen is considered a rapid evolutionary radiation nested within the larger notothenioid adaptive radiation, but the drivers of diversification in this clade remain unclear. Persistent uncertainty in species boundaries and phylogenetic relationships has prevented development of a robust evolutionary framework in which to investigate patterns of diversification. The broader objective of this project is to describe existing patterns of lineage, morphological, and ecological diversity of Patagonotothen fishes and to understand how this diversity evolved.

Project Objectives

• To use molecular and morphological data to delimit species boundaries and to infer evolutionary relationships among delimited species of Patagonotothen
• To integrate data on phylogeny, phenotype, and ecology in order to characterize evolutionary dynamics of trait disparity within the radiation

Year in review: July 2020 - June 2021

• 1 month placement at SAERI in the Falkland Islands, which provided opportunity for collection of whole fish specimens needed for quantification of phenotypic and ecological traits and tissue samples needed for DNA sequence data collection
• Extracted whole genomic DNA from tissue samples representing eight species of Patagonotothen; DNA will be sequenced for use in downstream species delimitation and phylogenetic analyses
• Collected data on body shape variation from whole specimens representing eight Patagonotothen species