The effects of mode of development on phylogeography and population structure of North Atlantic Crepidula (Gastropoda: Calyptraeidae)

Abstract

The mode of development of marine invertebrates is thought to influence levels of population structure and the location of species range endpoints via differences in dispersal ability. To examine these effects, populations of three sympatric clades of sedentary, marine gastropods in the genus Crepidula were sampled along the Atlantic and Gulf coasts of North America. A haplotype tree was constructed for each clade based on 640 bp sequences of mitochondrial cytochrome oxidase c subunit I. Examination of the tree topology, and AMOVA analysis show that species with direct development (those hatching as benthic juveniles) have higher levels of population structure than do species with planktonic development. Both species in the direct-developing C. convexa clade have high levels of geographical differentiation, with most populations representing a discrete clade of haplotypes. The planktotrophic species C. fomicata contains two major haplotype clades, both of which include samples from throughout the Atlantic coast. In this species there is no geographical differentiation among haplotypes but AMOVA analysis detects a small but statistically significant level of geographical structure. The population structure within the C. plana species complex appears also to vary with mode of development: C. atrasolea, a direct-developing species, has higher levels of population structure than does C. depressa, a sympatric planktotrophic species. The coincident occurrence of range endpoints and genetic breaks along the east coast of Florida in both direct-developing species and species with planktonic development indicates that this biogeographic break is not due to development-specific mechanisms such as hydrographic effects on larval recruitment.

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).…”

“…In contrast, the apparent lack of physical barriers, coupled with high dispersal potential, suggests that evolutionary mechanisms differ in diverse marine communities (Palumbi 1994;Myers 1997). However, as history, mode of development, and biogeographic zones appear to explain population structure in coastal areas, they may also play an important role in the determination of patterns of marine biodiversity (Engle and Summers 1999;Collin 2001;Wares 2002;Graham et al 2003). Indeed, glaciation has caused increased diversification and lineage extinction in northern coastal habitats (Hewitt 2000;Edmands 2001;Wares and Cunningham 2001;Marko 2004).…”

Genetic population structure of Neptune whelk in northern Japan inferred from microsatellite DNA variation

“…However, the correlation between dispersal ability estimated by the length of planktonic larval period and population structure is still controversial. For example, levels of geographic differentiation are elevated in species without planktonic larval stage in marine gastropods (Collin 2001, Lee & Bouldings 2009). Hair crab, Erimacrus isenbeckii (Brandt) (Azuma et al 2007) and Japanese scallop, Patinopecten yessoensis (Jay) (Nagashima et al 2003), both having inshore planktonic stages for a month or more, show indistinct genetic differentiation.…”

“…Also, poor correlation between pelagic larval duration and genetic structure has been suggested by an extensive literature survey of marine species (Weersing & Toonen 2009). These discrepant observations likely indicate that the length of planktonic larval stage may not be a sole determinant for the current and recent gene flow in marine organisms in general, as population structure may also be influenced by other factors, such as the whole life history and evolutionary history in a species concerned (Kyle & Bouldings 2000, Collin 2001, Lee & Bouldings 2009). Neptune whelk, Neptunea arthritica (Bernardi, 1857) (Gastropoda: Buccinidae), is distributed in the intertidal zone to 100-m depth in the Pacific Ocean, the Sea of Japan, and the Sea of Okhotsk along the coasts of northern Japan (Okutani 2000) and is commercially important in coastal fisheries.…”

Larval metamorphic competence in four species of Phestilla (Gastropoda; Opisthobranchia)

“…On the opposite end of the spectrum C. pennaceus has larvae that metamorphose into juveniles hours after hatching (Perron, 1981). The opisthobranch Alderia modesta has a range of larval types including planktotrophic and lecithotrophic veligers within the same egg clutches (Krug, 1998), and the potential biogeographic and genetic consequences of planktotrophic versus direct-development larval ecology is illustrated in three species of Crepidula (Collin, 2001).…”