Population genetic and phylogenetic insights into the adaptive radiation of Antarctic notothenioid fishes

• Main Author: Matschiner, Michael
• Other Authors: Salzburger, Walter, Hanel, Reinhold, Reusch, Thorsten
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: Antarctic; The Antarctic; Antarc*; Antarctica
• Online Access: http://edoc.unibas.ch/diss/DissB_9755; https://edoc.unibas.ch/1428/; https://edoc.unibas.ch/1428/1/Dissertation_Matschiner.pdf; https://doi.org/10.5451/unibas-005754102

Adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage, a phenomenon that is considered responsible for a great part of Earthʼs biodiversity. It occurs as a response to ecological opportunity in the form of competitor-free habitat, extinction of antagonists, or the emergence of a key innovation. One of the most spectacular adaptive radiations in the marine realm is the diversification of notothenioid fishes in the freezing waters of Antarctica. This radiation has led to a unique dominance of the Antarctic marine habitat by notothenioids, and is often assumed to result from the key innovation of freeze resistance. Antifreeze glycoproteins are present in blood and tissue of Antarctic notothenioids and enable them to survive in their sub-zero environment. Notothenioids are further characterized by prolonged pelagic larval stages, that have been suggested to contribute to high levels of inter-population gene flow with oceanic currents, which seems to contradict the high speciation rates observed in the notothenioid adaptive radiation. This doctoral work uses molecular tools to investigate the character of gene flow in notothenioids as well as the origin of their diversification. It is demonstrated that larval dispersal is a common agent of long-distance gene flow in many notothenioid species. The key innovation hypothesis is corroborated by an extensive molecular dating of the divergence events of notothenioids and related acanthomorph fishes. New tools for the analysis of microsatellite markers and for Bayesian divergence date estimation are developed.