The genomic and phenotypic basis of a biological invasion

Human impact has altered the adaptive landscape and has shifted the evolutionary trajectories of a huge number of species. Many species are able to survive, persist and adapt to a human niche, yet our knowledge of how humans indirectly alter traits, genes and the evolutionary processes involved is limited. The house sparrow (P. domesticus) is a widespread, charismatic and well-known example of a human-commensal bird. We have previously shown that the house sparrow spread from its native range in the Middle East into Europe alongside the movement of early agricultural societies during the Neolithic. However, due to deliberate introductions during the 19th Century, house sparrows have established in North America, South America and Australia. Has this more recent spread to new regions been facilitated by the same morphological and metabolic changes that led to the original shift to a human-dependent niche during the Neolithic? Or has it been driven by new adaptations such as changes in cognition or immune response? Fortunately, house sparrow introductions are well-documented and museum collections contain specimens sampled from the time of introduction to contemporary periods. This makes it possible to quantify changes in allele frequencies and phenotypes across the temporal scale that tracks the recent spread of this commensal species, providing evidence of selection and insight into adaptive mechanisms.
We have established a dataset of house sparrows sampled from 5 locations (Melbourne, Rio de Janeiro, New York, Toronto and San Francisco) at 20, 50 and 100-years post-introduction (15-20 samples per time period). Using whole genome resequencing, this project will first seek to test the hypothesis that modern house sparrow introductions have been founded by multiple independent evolutionary lineages. The second part of the project will be to identify genomic signatures of selection in populations from the introduced range of the house sparrow. In particular, we hope to use our unique time-series data to reconstruct allele frequency changes during the course of the introduction, focusing on a set of candidate genes involving cognition, beak shape, immune response and digestion. Combined with our contemporary dataset of >400 genomes from across the native range of the species, it will be possible to explicitly test whether selection has occurred on the same genes in the more recent spread. In addition to genomic data, we have access to museum collections with 1974 house sparrow individuals collected over the last 141 years. The project will use 3D morphometrics and photogrammetry to identify phenotypic evolution in house sparrows following introduction, focusing on craniofacial morphology.
The overarching aim of this project is to understand the spread of anthrodependent taxa in an evolutionary context and to shed light on the genomic and phenotypic basis of a biological invasion.