New expansions in old clades: population genetics and phylogeny of Gnatholepis species (Teleostei: Gobioidei) in the Pacific |
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Authors: | Christine E Thacker Andrew R Thompson Dawn M Roje Emily Y Shaw |
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Institution: | (1) Research and Collections—Ichthyology, Natural History Museum of Los Angeles County, 900 Exposition Blvd, Los Angeles, CA 90007, USA |
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Abstract: | Species of the reef goby genus Gnatholepis exhibit enormous geographic ranges with little evidence of population segregation detectable based on mitochondrial DNA.
To determine if genetic differentiation is evident with more rapidly evolving markers, seven microsatellite loci were screened
from the species Gnatholepis anjerensis and G. scapulostigma and population segregation was tested among fish from across the South Pacific. Both AMOVA and pairwise F
ST analyses showed that, in concordance with previous mitochondrial results, most genetic variance occurs within individual
populations, as population differentiation is evident only over the largest distances (>3,700 km). This result is contrasted
with previous studies demonstrating that despite their relatively long larval periods, some gobiid fishes exhibit population
differentiation on small (<100 km) geographic scales. Coalescence analysis showed that current Pacific populations of these
species originated in the Pleistocene, presumably related to sea level fluctuations associated with episodes of glaciation.
However, rate analysis based on a phylogeny of Gnatholepis species indicates that the species themselves are much older, consistent with a complex history of rapid, short-term population
contractions and expansions, with corresponding rapid dispersal. |
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