Colourful conservation: genetic incompability and conservation genetics in the wild Gouldian finch (Erythrura gouldiae)
thesisposted on 28.03.2022, 02:56 by Peri Bolton
The distinct behavioural and physiological strategies associated with colour morphs can influence population dynamics, where antagonistic interactions and hybrid incompatibilities may be detrimental. Therefore, the covariation between colour and other traits will be relevant to species conservation, but the negative implications have never been explored. Molecular genetic tools allow the measurement of selection on functional genotypes, and place it in the wider context of effective population size (Ne) and gene flow. The Gouldian finch (Erythrura gouldiae) is an Australian threatened species, and sympatric head colour morphs associated with distinct strategies. Experiments on domesticated Gouldian finches have shown that interbreeding between morphs leads to significant offspring mortality, which may be detrimental to population recovery. This species has been embroiled in recent controversy regarding its conservation status as there are no robust estimates of population size or movement capacity across its vast and remote range. In this thesis, I use population genetic techniques using microsatelites, mitochondrial DNA and SNPs to quantify Ne and gene flow across the contemporary range, and a novel allele-specific test for head-colour to determine the extent of incompatibility in the wild. Guided by predictions derived from the experiments on domesticated birds, I do not find any evidence of incompatibility, or strategies to avoid it. Furthermore, population genetic evidence suggests the contemporary range supports a single genetically cohesive population, and suggests individuals are able to move vast distances (>700km). The contemporary Ne is likely large, but there is still uncertainty in these estimates due to the dearth of fundamental knowledge of this species' life-history. Together, this work suggests that incompatibility is unlikely to be a threatening process in the wild, and has identified key knowledge gaps that currently hinder effective conservation management of the Gouldian finch.