Phylogeography of the marine interstitial nemertean Ototyphlonemertes parmula (Nemertea, Hoplonemertea) reveals cryptic diversity and high dispersal potential
- First Online:
We conducted a phylogeographic study of the meiofaunal nemertean Ototyphlonemertes parmula, an apparent species complex from the littoral zone of coarse-grained beaches, using a 494-bp fragment of the mitochondrial cytochrome oxidase 3 gene (cox3). Six populations from the Gulf and Atlantic coasts of Florida, two from New England, and one from the Caribbean were sampled in March and August 2005. Three major lineages were identified, separated by cox3 sequence divergence of 16–18%, with partially overlapping ranges. Tests for hybridization using ISSR markers detected nuclear gene exchange within but not between the major mitochondrial lineages, indicating the presence of cryptic species. One lineage dominating the Atlantic coast of Florida shows no evidence of geographic structuring. Another lineage shows a phylogenetic break between the Atlantic and Gulf coasts, suggesting that unsuitable habitat may act as a barrier to dispersal. Long-distance migration is evidenced by shared haplotypes between Florida and the eastern Caribbean. Overall, the widespread distribution of individual haplotypes and lack of structuring within geographic regions contrast with O. parmula’s strongly sediment-bound lifestyle. We speculate that dispersal of adults by storms and/or sediment transport may be more important than few and potentially short-lived planktonic larvae to explain geographic diversity in O. parmula and may be important for meiofauna in general.