MBL, WOODS HOLE, MA -- Tiny larval fish living among Australia's Great Barrier Reef spend the early days of their lives swept up in ocean currents that disperse them far from their places of birth. Given such a life history, one might assume that fish populations would be genetically homogeneous within the dispersal area. Yet the diversity of reef fish species is high and individual reefs contain different fish populations. For such rich biodiversity to have evolved, some form of population isolation is required.
New research from MBL (Marine Biological Laboratory) Associate Scientist Gabriele Gerlach, MBL Adjunct Senior Scientist Jelle Atema, and their colleagues shows that some fish larvae can discriminate odors in ocean currents and use scent to return to the reefs where they were born. The olfactory imprinting of natal reefs sheds light on how such a wide diversity of species arose. The homing behavior of reef fishes, the researchers contend, could support population isolation and genetic divergence that may ultimately lead to the formation of new species.
Gerlach, Atema, and their team will present the results of their research in next week's online Early Edition of The Proceedings of the National Academy of Sciences. The scientists studied fish populations in five neighboring reefs (all part of the Great Barrier Reef) where genetic mixing would be expected. They used a multidisciplinary approach including hydrodynamic modeling to describe prevailing ocean current distribution patterns among the reefs; genetic markers to track the relatedness of three species of fishes which live among the reefs; and olfactory choice tests using flumes to test the larvae's ability to smell the difference between water from the five reefs.
Their genetic analyses showed that while some fish species do disperse, other species return to their home reef. One species in particular, the cardinal fish (Ostorinchus doederleini), showed significant gene
Contact: Gina Hebert
Marine Biological Laboratory