Global climate change: The impact of El Niño on Galápagos marine iguanas

December 11, 2007

New Haven, Conn. -- A before-and-after study led by Yale biologists, of the effects of 1997 El Niño on the genetic diversity of marine iguanas on the Galápagos Islands, emphasizes the importance of studying populations over time and the need to determine which environmental and biological factors make specific populations more vulnerable than others.

According to the authors, recurring El Niño events provide an ideal system to study the impact of human-mediated climate change on ecosystems worldwide, by allowing observation of changes in populations associated with individual events.

"Since global warming is expected to cause an increase in the strength and frequency of El Niño events, it is important to evaluate the impact of El Niño on natural populations and their capacity to respond to environmental stresses," said Gisella Caccone, senior research scientist in ecology and evolutionary biology at Yale, and senior author of the paper published this week in the Public Library of Science (PLoS) One.

In this study, the researchers investigated the effect of sea surface warming associated with the single, intense El Niño event of 1997 to 1998 on genetic diversity in Galápagos marine iguana populations. They found that populations within the same species responded very differently.

Collaboration between German scientists who fortuitously collected and archived samples between 1991 and 1993 and Yale researchers who sampled the iguanas in 2004 enabled these unique before-and after comparisons. More than 800 samples from 11 Galápagos marine iguana populations were evaluated.

The researchers looked for changes in levels of genetic variation in nuclear microsatellite DNA and mitochondrial DNA markers of samples collected before and after this El Nino event. Changes in microsatellite frequency are sensitive enough to detect low population sizes before there is a significant loss of diversity in a population, whereas mitochondrial markers only show losses of diversity.

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 Niño-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 Niño, 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."
-end-
Other authors on the study are Deborah Lanterbecq at Yale, Cruz Marquez at the Charles Darwin Research Station, Santa Cruz, Galápagos, Ecuador and Kornelia Rassmann in Germany. Granting from the National Geographic Society, the German Research Community, the Belgian American Educational Foundation, and the Yale Institute for Biospheric Studies supported the research.

Citation: Public Library of Science (PLoS): December 12, 2007.

Available on line at http://www.plosone.org/doi/pone.0001285

Yale University

Related Genetic Diversity Articles from Brightsurf:

In the Cerrado, topography explains the genetic diversity of amphibians more than land cover
Study shows that a tree frog endemic to a mountainous region of the Brazilian savanna is unable to disperse and find genetically closer mates when the terrain is rugged, potentially endangering survival of the species

New DNA sequencing technique may help unravel genetic diversity of cancer tumors
Understanding the genetic diversity of individual cells within a cancer tumor and how that might impact the disease progression has remained a challenge, due to the current limitations of genomic sequencing.

Researchers uncover the arks of genetic diversity in terrestrial mammals
Mapping the distribution of life on Earth, from genes to species to ecosystems, is essential in informing conservation policies and protecting biodiversity.

Seahorse and pipefish study by CCNY opens window to marine genetic diversity May 08, 2020
The direction of ocean currents can determine the direction of gene flow in rafting species, but this depends on species traits that allow for rafting propensity.

Study helps arboreta, botanical gardens meet genetic diversity conservation goals
In a groundbreaking study, an international team of 21 scientists evaluated five genera spanning the plant tree of life (Hibiscus, Magnolia, Pseudophoenix, Quercus and Zamia) to understand how much genetic diversity currently exists in collections in botanical gardens and arboreta worldwide.

Study reveals rich genetic diversity of Vietnam
In a new paper, Dang Liu, Mark Stoneking and colleagues have analyzed newly generated genome-wide SNP data for the Kinh and 21 additional ethnic groups in Vietnam, encompassing all five major language families in MSEA, along with previously published data from nearby populations and ancient samples.

Coastal pollution reduces genetic diversity of corals, reef resilience
A new study by researchers at the University of Hawai'i at Mānoa School of Ocean and Earth Science and Technology found that human-induced environmental stressors have a large effect on the genetic composition of coral reef populations in Hawai'i.

New world map of fish genetic diversity
An international research team from ETH Zurich and French universities has studied genetic diversity among fish around the world for the first time.

Texas A&M study reveals domestic horse breed has third-lowest genetic diversity
A new study by Dr. Gus Cothran, professor emeritus at the Texas A&M School of Veterinary Medicine & Biomedical Sciences, has found that the Cleveland Bay horse breed has the third-lowest genetic variation level of domestic horses, ranking above only the notoriously inbred Friesian and Clydesdale breeds.

Genetic diversity facilitates cancer therapy
Cancer patients with more different HLA genes respond better to treatment.

Read More: Genetic Diversity News and Genetic Diversity Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.