No evidence of host specialization in a parasitic pea-crab exploiting two echinoid hosts

Abstract

The pinnotherid crab Dissodactylus primitivus lives parasitically on 2 burrowing echinoid species, Meoma ventricosa and Plagiobrissus grandis. The fecundity of female crabs varies between hosts, and is higher when parasitizing P. grandis than M. ventricosa. Moreover, the hosts present great variations in morphology (size and density of spines). These characteristics suggest the potential to differentiate crabs according to host species. We investigated the genetic (microsatellites) and morphometric (outline analysis) differentiation of this parasitic crab between 2 host species at 1 Jamaican site (Western Lagoon, Discovery Bay), and compared it with geographic differentiation among 4 sites along the north coast of Jamaica.Greater genetic differences between parasites of the 2 sympatric hosts than between parasites of a single host at different geographic locations would indicate host differentiation. Genetic analyses (microsatellites) did not detect spatial differentiation (probably due to local hydrography) or differentiation according to host species. This lack of host differentiation could be explained by mobility of adult crabs between hosts. However, there was weak but significant morphological differentiation between female crabs from the 2 hosts. This morphological difference may reflect constraints due to host morphology.

Genetic Evidence Confirms Polygamous Mating System in a Crustacean Parasite with Multiple Hosts

“…This result is in agreement with a previous population genetics study on a larger data set from Discovery Bay [22].…”

“…A higher fertility in pea-crab females living on P. grandis was observed [13]. A population genetics analysis revealed no genetic differentiation among crabs living on the two different host species, suggesting a lack of host specialization [22]. Consequently, the higher fertility of females living on P. grandis remained unexplained.…”

Characterization of eight microsatellite loci for the sea urchin Meoma ventricosa (Spatangoida, Brissidae) through Next Generation Sequencing

“…Microsatellite markers have already been characterized and validated for this crab (Anderson et al, 2010;Jossart et al, 2013). A comparative study could reveal the factors that influence dispersal of each species and provide information about their potential for local adaptation (Greischar and Koskella, 2007).…”

A Review of Molecular Approaches for Investigating Patterns of Coevolution in Marine Host–Parasite Relationships

“…Whether patterns of congruent genetic signals from microsatellites of both hosts and parasites also hold for obligate marine species remains largely unexplored and requires future investigations. A recent study by Jossart et al (2013) applied microsatellites to investigate the potential host specialization in a parasitic pea crab (Dissodactylus primitivus) in two echinoid species from different geographic regions. However, microsatellite analyses did not detect spatial differentiation or differentiation according to host species, which points to random mating and high gene flow between parasitic crabs from the two hosts.…”