title: Isolation and differentiation of Rivulus hartii across Trinidad and neighboring islands.
abstract: Diversification of freshwater fishes on islands is considered unlikely because the traits that enable successful colonization-specifically, broad salinity tolerances and the potential for oceanic dispersal-may also constrain post-colonization genetic differentiation. Some secondary freshwater fish, however, exhibit pronounced genetic differentiation and geographic structure on islands, whereas others do not. It is unclear what conditions give rise to contrasting patterns of differentiation because few comparative reconstructions of population history have been carried out for insular freshwater fishes. In this study, we examined the phylogeography of Hart's killifish (Rivulus hartii) across Trinidad, with reference to neighboring islands and northern South America, to test hypotheses of colonization and differentiation derived from comparable work on co-occurring guppies (Poecilia reticulata). Geographic patterns of mitochondrial DNA haplotype variation and microsatellite genotype variation provide evidence of genetic differentiation of R. hartii among islands and across Trinidad. Our findings are largely consistent with patterns of geographically structured ancestry and admixture found in Trinidadian guppies, which suggests that both species share a history of colonization and differentiation and that post-colonization diversification may be more common among members of insular freshwater fish assemblages than has been previously thought.
authors.affiliation: Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Walter
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Blum
authors.forename: Sunny B
authors.initials: SB
authors.lastname: Snider
authors.forename: Ian G
authors.initials: IG
authors.lastname: Paterson
authors.forename: Paul
authors.initials: P
authors.lastname: Bentzen
authors.forename: Brad A
authors.initials: BA
authors.lastname: Lamphere
authors.forename: James F
authors.initials: JF
authors.lastname: Gilliam
mesh_terms: D000818:Animals; D003532:Cyprinodontiformes / Q000145:classification / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D005618:Fresh Water; D049810:Genetic Speciation; D014644:Genetic Variation; D006239:Haplotypes; D018895:Microsatellite Repeats / Q000235:genetics; D058974:Phylogeography; D011036:Poecilia / Q000145:classification / Q000235:genetics; D011157:Population Dynamics; D014300:Trinidad and Tobago; D014900:West Indies
chemical_list: D004272:DNA, Mitochondrial