TY  - JOUR
AB  - Background: Marine iguanas (Amblyrhynchus cristatus) inhabit the coastlines of large and small islands throughout the Galapagos archipelago, providing a rich system to study the spatial and temporal factors influencing the phylogeographic distribution and population structure of a species. Here, we analyze the microevolution of marine iguanas using the complete mitochondrial control region (CR) as well as 13 microsatellite loci representing more than 1200 individuals from 13 islands. Results: CR data show that marine iguanas occupy three general clades: one that is widely distributed across the northern archipelago, and likely spread from east to west by way of the South Equatorial current, a second that is found mostly on the older eastern and central islands, and a third that is limited to the younger northern and western islands. Generally, the CR haplotype distribution pattern supports the colonization of the archipelago from the older, eastern islands to the younger, western islands. However, there are also signatures of recurrent, historical gene flow between islands after population establishment. Bayesian cluster analysis of microsatellite genotypes indicates the existence of twenty distinct genetic clusters generally following a one-cluster-per-island pattern. However, two well-differentiated clusters were found on the easternmost island of San Cristobal, while nine distinct and highly intermixed clusters were found on youngest, westernmost islands of Isabela and Fernandina. High mtDNA and microsatellite genetic diversity were observed for populations on Isabela and Fernandina that may be the result of a recent population expansion and founder events from multiple sources. Conclusions: While a past genetic study based on pure FST analysis suggested that marine iguana populations display high levels of nuclear ( but not mitochondrial) gene flow due to male-biased dispersal, the results of our sex-biased dispersal tests and the finding of strong genetic differentiation between islands do not support this view. Therefore, our study is a nice example of how recently developed analytical tools such as Bayesian clustering analysis and DNA sequence-based demographic analyses can overcome potential biases introduced by simply relying on FST estimates from markers with different inheritance patterns.
DA  - 2009
DO  - 10.1186/1471-2148-9-297
LA  - eng
IS  - 1
M2  - 297
PY  - 2009
SN  - 1471-2148
SP  - 297-
T2  - BMC Evolutionary biology
TI  - Progressive colonization and restricted gene flow shape island-dependent population structure in Galapagos marine iguanas (Amblyrhynchus cristatus)
UR  - https://nbn-resolving.org/urn:nbn:de:0070-pub-15889045
Y2  - 2024-11-22T09:05:40
ER  -