HOLLAND, B.S.; COWIE, R.H.; Univ. of Hawaii; Univ. of Hawaii: Molecular phylogeography of a dry-land, ephemeral endemic Hawaiian snail (Succinea caduca)
The Succineidae represent a diverse land snail family in Hawaii, and a classic example of an adaptive radiation. Succineids have been successful at dispersing across geographic barriers, as evidenced by their circum-global distribution. In the Hawaiian Islands, they have colonized most habitat-types, including high mesic, arid coastal, and cloud forest areas. High growth rate and fecundity have led to several species faring well compared to most Hawaiian land snails due to habitat destruction and predation by alien species. Succineids offer a good model for testing evolutionary and biogeographic theories. We used fragments of the COI, 16S, and H3 genes to infer relationships among six lowland populations of Succinea caduca from Oahu and two morphologically similar species, S. konaensis and S. quadrata, from upland sites on Hawaii. Analysis of a preliminary global succineid dataset reveals a monophyletic clade of species from Oahu and Hawaii, with S. caduca representing a well-supported lineage, distributed across Oahu, with S. konaensis and S. quadrata sister to one another. Succinea caduca is not the oldest species in the lineage, though Oahu is older than Hawaii, and is relatively closely related to the S. konaensis/S. quadrata clade (maximum K2P distance 6.3 %). However, several morphologically divergent upland wet forest taxa from the island of Hawaii comprise a clade sister to the S. konaensis and S. quadrata clade, while the morphologically similar S. caduca is more distantly related, although within the Oahu-Hawaii clade. Interestingly, collection sites have been surveyed many times over the last 5 yr and S. caduca had not been found until recently, following excessive, protracted rainfall, when thousands of specimens were observed amassing in ephemeral pools and flowing water in low-lying normally dry areas at opposite ends of Oahu (Makapuu Point, Kaena Point).
