Phylogeography of the Patelloida profunda group (Gastropoda: Lottidae): diversification in a dispersal‐driven marine system

Abstract

In the last decade, greater than expected levels of genetic structure have been reported for many marine taxa with high dispersal capabilities. Although little-studied to date, it is predicted that taxa with poor dispersal abilities would exhibit even more genetic differentiation than high dispersal taxa. These systems may track biogeographical processes better than more dispersive taxa and, more critically, function as the 'lowest common denominators' in MPA design initiatives. We investigate phylogeographical patterns in the poorly dispersing, yet widely distributed Patelloida profunda group and related congeners across the Indo-west Pacific region. One hundred and twenty-five individuals were sequenced for COI mtDNA [593 base pairs (bp)] and 44 individuals were sequenced for 16S mtDNA (539 bp). Identified P. profunda group lineages are highly geographically structured, with 12 reciprocally monophyletic lineages reported from 13 localities. Divergences within Indian and Pacific basins range from d = 0.013 to 0.127 and between basins from d = 0.147 to 0.197. The latter split is ancient (> 15 Myr) and cannot be related to Plio-Pleistocene sea-level fluctuations, characteristic of previously reported divergences in the same region. Juxtaposed against this structure is genetic connectivity between two widely separated P. profunda populations that share a common haplotype (phiST = 0.001). This finding contrasts with previous work in the same geographical region and cautions strongly against single taxon indicators for designing conservation priorities or marine protected areas (MPAs). Historical and/or biological factors may play more significant roles than oceanography alone in determining the genetic structuring of taxa. In light of these findings, we discuss the difficulty in deriving biogeographical process or directionality from phylogenetic trees in dispersal-driven systems. Even with a well-resolved, highly supported topology, many equally parsimonious scenarios are possible.

Placing the Floridian Marine Genetic Disjunction Into a Regional Evolutionary Context Using the Scorched Mussel, Brachidontes Exustus, Species Complex

“…Or might they be best described as open systems (Mora and Sale 2002)? Evidence can be found for a spectrum of connectivity, from extensive (in the absence of biogeographic barriers) for species with broad larval dispersal potential (Lessios et al 2001;Rocha et al 2002) to almost nonexistent in many nominal taxa with reduced pelagic larval development (Kirkendale and Meyer 2004;Meyer et al 2005). Of particular interest are taxa, such as the scorched mussel species complex, in which pronounced latent genetic structuring persists despite extended pelagic larval development (Barber et al 2002;Taylor and Hellberg 2003a;Williams and Reid 2004).…”

Phylogeny and Genetic Diversity of Palolo Worms (Palola, Eunicidae) from the Tropical North Pacific and the Caribbean

“…Only a small percentage of the haplotypes (7.7% for COI; 12.5% for 16S) are shared among locations, but they represent a large percentage of the sampled individuals (40% for both markers) and cover six of the nine collecting locations (Tables 7 and 8). Several recent studies have shown strong geographic population structure in marine shallow-water invertebrates, even in taxa with high dispersal capabilities (e.g., Kirkendale and Meyer, 2004, and references therein). It is therefore surprising to find widespread, in some cases extremely widespread, haplotypes and clades in Palola, especially considering that all known eunicid larvae are short-lived and lecithotrophic (Richards, 1967).…”

Mitochondrial DNA variation and cryptic speciation within the free-living marine nematode Pellioditis marina

“…Such complexes are especially prominent in small invertebrates with few taxonomically diagnostic characters (Rocha-Olivares et al 2001). This taxonomic confusion evidently complicates the interpretation of distribution and dispersal patterns in the marine environment (Kirkendale & Meyer 2004).In this study, we investigate the population genetic structure of the free-living marine nematode Pellioditis marina Andrassy, 1983 (syn. Rhabditis marina Bastian, 1865) over a fairly small geographic area.…”