Dispersal, Coral reef fish, Microsatellite, Genetic structure, Temporal, Spatial
Dispersal in marine systems is a critical component of the ecology, evolution, and conservation of such systems; however, estimating dispersal is logistically diYcult, especially in coral reef fish. Juvenile bicolor damsel-fish (Stegastes partitus) were sampled at 13 sites along the Mesoamerican Barrier Reef System (MBRS), the barrier reefs on the east coast of Central America extending from the Yucatan, Mexico to Honduras, to evaluate genetic structure among recently settled cohorts. Using genotype data at eight microsatellite loci genetic structure was estimated at large and small spatial scales using exact tests for allele frequency diVerences and hierarchical analysis of molecular variance (AMOVA). Isolation-by-distance models of divergence were assessed at both spatial scales. Results showed genetic homogeneity of recently settled S. partitus at large geographic scales with subtle, but signiWcant, genetic structure at smaller geographic scales. Genetic temporal stability was tested for using archived juvenile S. partitus collected earlier in the same year (nine sites), and in the previous year (six sites). The temporal analyses indicated that allele frequency diVerences among sites were not generally conserved over time, nor were pairwise genetic distances correlated through time, indicative of temporal instability. These results indicate that S. partitus larvae undergo high levels of dispersal along the MBRS, and that the structure detected at smaller spatial scales is likely driven by stochastic eVects on dispersal coupled with microgeographic eVects. Temporal variation in juvenile cohort genetic signature may be a fundamental characteristic of connectivity patterns in coral reef fishes, with various species and populations diVering only in the magnitude of that instability. Such a scenario provides a basis for the reconciliation of conXicting views regarding levels of genetic structuring in S. partitus and possibly other coral reef fish species.
Hepburn, R. I.; Sale, P. F.; Dixon, B.; and Heath, Daniel D.. (2009). Genetic structure of juvenile cohorts of bicolor damselfish (Stegastes partitus) along the Mesoamerican barrier reef: chaos through time. Coral Reefs, 28, 277-288.
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