A project undertaken at the University of Melbourne, and supervised by Tyrone Lavery
In nature, where the same environments appear repeatedly (e.g. across a chain of islands), evolution is given repeat chances to solve the same problems. Sometimes, the responses are remarkably similar, and the same types of species evolve independently in different places (a phenomenon known as parallel evolution). Such examples can provide deep insights into how biodiversity forms.
This project uses the Solomon Islands archipelago, in one of the world’s global biodiversity hotspots, to explore how parallel evolution shapes wildlife. Across these islands are a group of leaf-nosed bats (Hipposideros) that look relatively similar from island to island, but vary greatly in body size. A medium-sized (H. diadema) and large species (H. dinops) co-occur through most of the archipelago, and a third, smaller species (H. demissus) is confined to the island of Makira. These bats have long been regarded as three distinct species, but our preliminary data have suggested a very different story.
By examining genetic data from bats on multiple islands, we found that large body size has evolved independently several times. Rather than one widespread species, the same “large bat” form has emerged repeatedly on different islands, shaped by similar environmental pressures. Even more surprising, on individual islands large and medium-sized bats are often very closely related, suggesting these differences arose recently. Despite the close relationships, the bats do not appear to interbreed.
Our project will aim to identify the features of island environments that are driving the repeat evolution of large body size, how quickly these traits evolve, and how new species remain distinct even when they live side by side. To do this, we combine several approaches, conducting genetic analyses, collecting physical measurements, studying ecology and diet, and making behavioural observations. By revealing how evolution repeatedly generates new forms in island settings, this project will improve our understanding of how biodiversity arises and how best to protect it.