A genetic study of island lizards shows that even those that have been geographically isolated for many millions of years have not evolved into separate species as predicted by conventional evolutionary theory. Professor Roger Thorpe and colleagues Yann Surget-Groba and Helena Johansson, at Bangor University, UK, reveal their findings April 29 in the open-access journal PLoS Genetics.
Since Darwin's study of the Galapagos Islands, archipelagos have played a central role in understanding how new species evolve from existing ones (speciation). Islands epitomize allopatric speciation, where geographic isolation causes individuals of an original species to accumulate sufficient genetic differences to prevent them breeding with each other when they are reunited.
Current day Martinique in the Lesser Antilles is composed of several ancient islands that have only recently coalesced into a single entity. The phylogeny and geology show that these ancient islands have had their own tree lizard (anole) species for about six to eight million years.
Capitalizing on the islands' meeting, the authors genetically tested the lizards for reproductive isolation from one another. In using selectively neutral genetic markers, the authors saw that these anoles are freely exchanging genes and therefore not behaving as separate species. Indeed, there is more genetic isolation between conspecifics from different habitats than between those lizards originating from separate ancient islands.
The findings reject allopatric speciation in a case study from a system thought to exemplify it, and suggest the potential importance of speciation due to differences in ecological conditions (ecological speciation). "The next step is to identify the genes controlling the traits influencing the process of speciation", said Roger Thorpe.
FINANCIAL DISCLOSURE: This research was primarily supported by the BBSRC (BB/C500544/1) with additional fellowship (YSG, RST) support from the EC (MEIF-CT-2005-009981) and studentship support (HJ, RST) from NERC (NER/S/A/2004/12449). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
COMPETING INTERESTS: The authors have declared that no competing interests exist.
CITATION: Thorpe RS, Surget-Groba Y, Johansson H (2010) Genetic Tests for Ecological and Allopatric Speciation in Anoles on an Island Archipelago. PLoS Genet 6(4): e1000929. doi:10.1371/journal.pgen.1000929
IN YOUR COVERAGE, PLEASE USE THIS URL TO LINK TO THE FREELY AVAILABLE ARTICLE (the link will go live when the embargo ends): http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1000929
+44 (0)1248 382312
This press release refers to an upcoming article in PLoS Genetics. The release is provided by the article authors and their institutions. Any opinions expressed in this release or article are the personal views of the journal staff and/or article contributors, and do not necessarily represent the views or policies of PLoS. PLoS expressly disclaims any and all warranties and liability in connection with the information found in the releases and articles and your use of such information.
About PLoS Genetics
PLoS Genetics (http://www.plosgenetics.org) reflects the full breadth and interdisciplinary nature of genetics and genomics research by publishing outstanding original contributions in all areas of biology.
About the Public Library of Science
The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world's scientific and medical literature a freely available public resource. For more information, visit http://www.plos.org.
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.