Genomics and ecology of rapid adaptation: the expansion and evolution of the invasive common myna (Acridotheres tristis) and common starling (Sturnus vulgaris) in New Zealand
Invasive species are one of the main drivers of biodiversity loss and information on their ecology and genetics can provide useful insights for their management. Invasive species, while harmful to native ecosystems, constitute “natural experiments” and offer uniquely replicated model systems to study evolution. The common myna (Acridotheres tristis) and the common starling (Sturnus vulgaris), members of the Sturnidae family, are two of the most invasive bird species in the world and are invasive in New Zealand. This thesis aims to evaluate the evolution of the two species following introduction, with the common myna as the main focal species. Firstly, I used reduced representation sequencing data to identify the origin and structure of myna populations, with emphasis on New Zealand. Two sub-populations in New Zealand were identified, divided by the North Island axial mountain range, suggesting independent introductions. All mynas in New Zealand were likely introduced from Melbourne, Australia, which in turn were founded by birds from a sub-population from Maharashtra, India. Secondly, I utilised ecological data to characterise the niches of both the common myna and common starling. For both species, I found no evidence of niche divergence between the native range and New Zealand, but evidence of niche differences between the two species in New Zealand. Future suitable habitats were projected under different climate change scenarios and highlighted areas at risk of future invasions in New Zealand. Lastly, I utilised whole-genome resequencing data from 82 myna individuals from four native and seven invasive populations, representing two independent introduction pathways, to identify parallel signatures of selection associated with invasion. A strongly selected region was identified on chromosome 8, encompassing two copies of an alpha-amylase gene, a non-coding RNA, and a structural variant containing a transposable element. Variants were fixed or close-to-fixed in invasive populations but polymorphic in native populations. Genes in the alpha-amylase family have been associated with adaptation to high-starch diets in sparrows, humans, and dogs. In summary, by uncovering the unique invasion history, this thesis provides evidence of rapid adaptation, highlights areas at risk of future invasion and provides a basis for future ecological and genomic studies.
myna, population genomics, adaptation genomics, local adaptation, whole genome resequencing, DArTseq, Acridotheres, ecological niche modelling, genomics, ecology
Networked Digital Library of Theses and Dissertations