As a result of the study, the researchers recommend that the genetically distinct population of franciscanas to the north of Buenos Airesprobably created in part by oceanographic conditionsshould be protected as part of a larger effort to save the species.
The research team started its investigation on the molecular level, one of the most efficient ways of determining the structure of marine animal populations. Working at the American Museum of Natural History's Sackler Institute for Comparative Genomics, researchers compared 275 genetic samples from dolphins that had been stranded, entangled in fishing gear, or captured and released in six locations along coastal Argentina (the southern portion of the animal's full range). Using genetic markers to statistically gauge the geneflow between dolphin groups at different sites, the scientists discovered that there are twoand possibly threedistinct populations of franciscanas in Argentina's coastal waters.
What really sets the study apart is the use of region-wide satellite data that shows how environmental differencestemperature, turbidity, and chlorophyll levelsare probably involved in creating those genetically distinct populations. The oceanographic data was provided by NASA's SeaWiFS and MODIS, two satellites designed to gather information on oceanic conditions.
The combination of genetic and environmental information allowed the scientists to examine the effects of detectable habitat differences on population structure in franciscanas. Specifically, researchers were able to test the role of two biological hypotheses on population formation, one based on the assumption that geneflow between two groups decreases with distance, and one based on decreased geneflow as a result of environmental barriers (the latter of which is easy to detect with terrestrial species separated by mountains, and usually undetectable in marine environments over wide areas).
|Contact: John Delaney|
Wildlife Conservation Society