Population genetic structure of New Zealand's endemic corophiid amphipods: evidence for allopatric speciation

Abstract

Allozyme electrophoresis was used to examine population genetic structure at inter-and intraspecific levels for the New Zealand endemic corophiid amphipods, Paracorophium lucasi and P. excavatum. Individuals were collected from estuarine and freshwater habitats from North, South and Chatham Islands. Analyses of genetic structure among interspecific populations indicated clear allelic differentiation between the two Paracorophium species (Nei's genetic distance, D = 1.62), as well as considerable intraspecific substructuring (D = 0.15-0.65). These levels of divergence are similar to interspecific levels for other amphipods and it is proposed that at least two groups from the P. lucasi complex and three from the P. excavatum complex correspond to sibling species. In most cases allopatry can account for the differentiation among the putative sibling species. For populations that share a common coastline we found low levels of differentiation and little or no correlation with geographical distance, suggesting that gene flow is adequate to maintain homogeneous population genetic structure. By contrast, populations on separate coastlines (i.e. isolated by land) showed moderate levels of geographical differentiation indicating restricted gene flow. The juxtaposition of population genetic and biogeographical data for Paracorophium in conjunction with the geological record infers past histories of glacial extirpation, and possible isolating effects of sea-level and landmass changes that have occurred throughout the Plio-Pleistocene.

Vicariance and Dispersal Effects on Phylogeographic Structure and Speciation in a Widespread Estuarine Invertebrate

“…3) with the break occurring across Cape Hatteras, where steep temperature gradients and currents converge at the Virginian and Carolinian provincial boundaries (Palumbi 1994; Engle and Summers 1999). Here, breaks or range point ends in other species are linked to dispersal ability and the physical conditions (Saunders et al 1986;Bastrop et al 1998;Jones and Quattro 1999;Collin 2001), which likely preclude gene flow through vicariance or selection (Palumbi 1994;Sotka et al 2004;Stevens and Hogg 2004).…”

Colonisation and connectivity by intertidal limpets among New Zealand, Chatham and Sub-Antarctic Islands. I. Genetic connections

“…Today, the complexity arises through mixing of Sub-Tropical and Sub-Antarctic water (Fig. 1) (Emberson 1995, Stevens & Hogg 2004, McGaughran et al 2006, Liggins et al 2008.In the present study 3 mitochondrial genes were used to assess the genetic structure of the Cellana strigilis complex from mainland New Zealand, the Chatham Islands and 4 Sub-Antarctic islands: Auckland Island, Campbell Island, Bounty Island, and Antipodes Island (Fig. 2).…”

Allozyme and mitochondrial DNA variability within the New Zealand damselfly generaXanthocnemis, Austrolestes, andIschnura(Odonata)

“…in the case of the recently-arrived I. aurora, minimal variation is consistent with a founder effect (Rowe 1987). However, the absence of variation for A. colensonis even among widely separated sites (e.g., chatham islands versus North and South islands), was surprising given that at least some differences were expected based from previous work (e.g., Trewick 2000;Hogg et al 2002;Stevens & Hogg 2004;mcgaughran et al 2006). accordingly, these available data suggest Ischnura.…”