Evolutionary causes and consequences of human-commensalism in Eurasian Passer sparrows
Humans have drastically altered the planet and are continuing to do so. Though the impact of these changes on biodiversity are generally negative, some species have rapidly adapted to novel niches opened up by human activity. The house sparrow (Passer domesticus) is a successful human commensal that thrives in human created niches. It has adapted to urban and agricultural habitats almost everywhere humans are present. Intriguingly, a number of other Passer sparrows are also human commensals having likely experienced similar selective pressures. Has anthrodependency arisen just once and spread via introgressive hybridization, or has it evolved in parallel in these birds? Are similar genes and phenotypes involved in independent adaptation to a human niche? What are the consequences of human commensalism for morphology, physiology, and behaviour and species interactions?
We will investigate these questions in an innovative and ambitious project addressing three objectives. (1) Multiple divergent lineages of the house sparrow occur in Central Asia, its native range and historically overlapped with distinct early agricultural civilizations. We will reconstruct the evolutionary history of the house sparrow to test whether human commensalism has a single origin or has arisen multiple times in this species. (2) Next, we will investigate the origins of human commensalism in the tree sparrow (Passer montanus), a distantly related species that replaces the house sparrow in the commensal niche across Eastern Asia. In particular, we will ask whether the tree sparrow also evolved alongside early agricultural society in China and whether there is evidence of parallel evolution of adaptation to a human niche. (3) Finally, we turn our attention towards the consequences of human commensalism and its impact on interactions among anthrodependent species and their wild counterparts where they co-occur, testing explicitly for competition for resources, assortative mating and reproductive isolation.