What controls gene flow in the ocean? The lack of physical barriers should produce homogenous genetic populations world-wide, but this does not seem to be the case. This project investigates the environmental factors controlling species dispersal and gene flow.
Macroevolution is the generation, proliferation and removal of species. The lack of physical barriers and large population size of most marine species should allow for rapid dispersal and colonization of new habitats following speciation. However, evidence suggests gene flow is more limited than expected: diachronous first occurrence dates among and within ocean basins of many species of planktonic foraminifera suggest that populations are slow to become widely established geographically. These observations indicate that i) physical barriers to dispersion in the open ocean are stronger than commonly invoked, and ii) the identity of these barriers and their working mechanisms are poorly understood.
Planktonic foraminifera are ideally suited for in-depth studies of temporal dispersal dynamics because their detailed and highly complete fossil record in marine sediments allows for reconstructions of population dynamics across space and through time. Using sediments recovered during IODP Expedition 383, this project studies the environmental drivers of species dispersal and migration in the sub-polar Southern Pacific Ocean, a region that, via the Drake Passage, connects the Pacific and Atlantic Oceans but lies at the edge of many species' geographical ranges. We will document foraminifera evolution at three of these sites (U1539, U1540 and U1541) and compare their evolutionary histories to geochemical reconstructions of environmental variability in the Antarctic Circumpolar Current (ACC).
Funding dates: 17 May 2019 - 17 November 2020
Funding provider: The project is funded by a UK-IODP Moratorium Grant, which is awarded by the Natural Environment Research Council
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