South Atlantic
Environmental Research
Institute

Investigating the drivers of diversification in a non-Antarctic notothenioid radiation

Funding Bodies: Yale University

Affiliations: Yale University, SAERI

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
Year in review : July 2022 - June 2023:

In early 2023, I conducted fieldwork in the Falkland Islands to sample the nearshore marine fish fauna, specifically targeting species of Patagonotothen and other non-Antarctic notothenioids. Voucher specimens collected during this trip were photographed for downstream quantification of body shape variation across Patagonotothen species, and tissue samples were used for the collection of DNA sequences for downstream molecular phylogenetic analyses of Patagonotothen.

I completed my PhD at Yale University in mid-2023 and started a postdoctoral fellowship at the University of Chicago, where I will continue to work on investigating the dynamics of diversification in Patagonotothen.
Year in review : July 2023 - June 2024:

In late May 2023, I defended my dissertation entitled “Drivers and dynamics of diversification in the Antarctic notothenioid adaptive radiation.” Dissertation was submitted to the University in August 2023, and doctoral degree was awarded in December 2023.
The rest of summer 2023 was spent photographing Patagonotothen specimens housed at the Yale Peabody Museum (including specimens collected during my 2020 and 2023 field trips to the Falkland Islands) for downstream landmark-based geometric morphometric analysis of body shape across the genus. I additionally extracted whole-genomic DNA from nearly 200 tissue samples representing nine species of Patagonotothen, and these extractions will be used in a molecular phylogenetic analysis of the genus to be completed before the end of 2024. In September 2023, I began a postdoctoral fellowship at the University of Chicago, where my research is focused on evaluating diversification in feeding biomechanics across all notothenioids, including the genus Patagonotothen. To this end, between April and June 2024, I collected computed tomography (CT) scans for a total of 19 specimens representing nine species of Patagonotothen. These scans will be used to generate a 3D landmark-based geometric morphometric dataset capturing variation in skull shape and feeding structures across the genus.

Elyse Parker

Dates: Jan 2020 - Dec 2023
Bio
Elyse is currently a PhD candidate at Yale University and has returned to studying Antarctic and sub-Antarctic notothenioids. Her dissertation is focused on investigating patterns of phenotypic, ecological and genetic diversity of notothenioids and understanding how this diversity evolved. To this end, she is working with Dr. Paul Brickle (SAERI) to investigate the evolutionary history of the notothenioid subclade Patagonotothen, which is distributed around the Falkland Islands and southern South America.
Sampling site at Camilla Creek, Falkland Islands.
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