Aim We investigate the origin and colonization of the West Indian endemic freshwater fish group Limia. We evaluate the leading hypotheses for the origins of West Indian life, including trans-oceanic dispersal, late Cretaceous vicariance, and the GAARlandia land bridge at the Eocene/Oligocene boundary.Location Greater Antilles, with extensive sampling in the Dominican Republic.Methods We obtained DNA from wild sampling and the aquarium trade. We sequenced three mitochondrial (12S, ND2 and Cytb) and two nuclear genes (Rh, MYH6) for a combined molecular phylogenetic analysis to evaluate species relationships and the timing of divergence events between islands and the mainland. We used Bayesian and likelihood approaches to build phylogenies, a BEAST analysis to establish the timing of colonization, and R package BioGeo-BEARS to perform a historical biogeographical reconstruction.Results Relaxed molecular clock results show that the ancestor to the West Indian clade, which includes the Limia and Hispaniolan Poecilia, diverged from a South American ancestor at the Eocene/Oligocene boundary. The basal Jamaican species, L. melanogaster, split from the rest of Limia at the Oligocene/ Miocene boundary. Cuban and Cayman taxa are sister to a diverse species group from Hispaniola. Historical biogeographical reconstruction supported the GAARlandia DEC+j model as the best fitting model for colonization. Main conclusionsOur results support a colonization model for Limia that is concordant with the timing of GAARlandia and climate change during the Eocene/Oligocene boundary. Limia colonization was most likely a result of facilitated dispersal during a period of lower sea levels and shorter passage along the Aves Ridge. These results are also consistent with other recent molecular clock studies of dispersal limited cichlids, toads and frogs, indicating a growing body of support for the significance of Eocene/Oligocene climate change for the historical biogeography of West Indian life.

We aim to show how a combination of molecular systematics and ecological niche modelling approaches can be used to test historical biogeographical hypotheses for species of conservation concern. We focus on the land snail genus Oreohelix (Oreohelicidae), a group found throughout the Rocky Mountains. In addition to its larger distribution, a group of Oreohelix is also found in the Black Hills of Wyoming and South Dakota, an isolated, easternmost extension of the Rocky Mountains. We determine the number, distribution, and relationships of Black Hills Oreohelicids, which are a current conservation concern due to their fragmented distribution. We compared Black Hills groups to those in the main part of the Rockies to test historical biogeographical patterns that explain current diversity. We collected mtDNA data (COI and 12S sequences) from multiple populations of Oreohelix throughout the Black Hills and in adjacent populations in the Rocky Mountains to construct phylogenetic hypotheses. To determine whether favourable environmental conditions currently exist between the Black Hills and the north-eastern Rocky Mountains, we used DesktopGARP to generate an ecological niche model for distinct lineages discovered in the molecular phylogenetic analysis. Results show that all Black Hills populations are likely Oreohelix cooperi and that little genetic differentiation exists within this clade. In addition, Black Hills groups are genetically similar or identical to populations found in the Judith Mountains and Bighorn Mountains (northeastern Rockies). Ecological niche models show that suitable environmental conditions may exist between eastern Rockies and Black Hills O. cooperi samples. Taken together, the phylogenetic and niche model data, along with the low vagility of the snails, support passive long-distance dispersal as a likely explanation for current arrangement of biodiversity.

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