Caccone said that although some populations had mortality rates of up to 90%, only one population from a single island showed strong evidence of a genetic bottleneck, suggesting that the El Nio-induced disturbance affected populations very differently even within the same species.
Our study points out that there was a low population size on the island of Marchena during the same period in which there was serious volcanic activity as well as the El Nino, said Yale graduate student Scott Glaberman, a principal author of the study. Since both of these forces could have acted on the population, it shows the importance of knowing the major forces influencing survival and reproduction to best interpret the results of genetic tests.
The most striking result of our study is that although marine iguanas on some islands had a rather high mortality due to El Nio, the genetic consequences were mostly absent, said author Sebastian Steinfartz a postdoctoral fellow. This unique study shows that natural populations may be able to balance even severe short term climatic disturbances, and that such fluctuations will not necessarily have long-term negative consequences on the population structure.
Basic surveys and ecology of organisms are not the most glamorous aspects of research, but if used together with the exciting genetic approach in our study, they make for a very powerful approach, said Glaberman.
This underscores the importance of having baseline studies for any population of interest, and the value of archiving samples for the use of future research, Caccone said. It sets the basis for future research to determine which environmental and biological factors make specific populations more vulnerable than others.
|Contact: Janet Rettig Emanuel|