Evolutionary Island Biogeography: Origins and Maintenance of Fish Biodiversity in Marine Lakes

For over 150-years, insular environments have played a key role in biological research, as they provide an explicit spatial and temporal context in which to study the processes behind biodiversity.

Traditionally, the origin and maintenance of biodiversity in islands has been studied from the ecological aspects of biogeography such as immigration, colonization and extinction, while microevolutionary processes such as adaptation were ignored.

Biodiversity in islands depends not only on colonization, but also on the successful establishment via biological adaptations, and on speciation. The integration of microevolution with Island Biogeography Theory (IBT) is a crucial next step.

Here I propose to use marine lakes –islands of seawater surrounded by land– to shed light on the origin and maintenance of fish biodiversity by understanding the interaction between colonization, extinction and adaptation.

To achieve this, I will compare marine lakes of similar ages, sizes and environmental conditions, but differing in the level of isolation to the sea, in Raja Ampat, Indonesia.

First, I will examine how isolation and fish dispersal-related traits affect species diversity and composition in marine lakes.

I will document marine lakes biodiversity patterns using video camera recordings and I will collate information on traits from public data repositories.

Second, I will test how isolation affects colonization and extinction by documenting historic colonization-extinction dynamics (750-years before the present) using eDNA from sediment cores.

Finally, I will test how isolation affects local adaptation by examining signatures of adaptation in marine lakes with different levels of connectivity to the sea using population genetics.

This unique combination of study system, data, and novel analyses to integrate microevolution with IBT, will provide a more comprehensive understanding of the process responsible for the origin and maintenance of biodiversity.