Genetic parentage assessment in the crayfish Orconectes placidus, a high‐fecundity invertebrate with extended maternal brood care

Abstract

Microsatellite data have recently been introduced in the context of genetic maternity and paternity assignments in high-fecundity fish species with single-parent-tended broods. Here we extend such analyses to an aquatic invertebrate, the crayfish Orconectes placidus, in which gravid females carry large numbers of offspring. Genetic parentage analyses of more than 900 progeny from 15 wild crayfish broods revealed that gravid females were invariably the exclusive dams of the offspring they tended (i.e. there was no allomaternal care), and that most of the females had mated with multiple (usually two) males who contributed sometimes highly skewed numbers of offspring to a brood. Within any multiply sired brood, the unhatched eggs (or the hatched juveniles) from different fathers were randomly distributed across the mother's brood space. All of these genetic findings are discussed in the light of observations on the mating behaviours and reproductive biology of crayfish.

Genetic parentage in the squat lobsters Munida rugosa and M. sarsi (Crustacea, Anomura, Galatheidae)

“…The logistical difficulties in characterising genotypes of the high number produced by some crustacean species has resulted in studies (e.g. Urbani et al 1998, Walker et al 2002, Gosselin et al 2005) implementing a pooling approach. The drawback of such an approach is that the true number of males can be significantly underestimated, particularly if the male contribution is highly skewed; therefore, we elected to screen individual eggs.…”

“…rock shrimp), are characterised by multiple mating. While it is still unknown as to whether multiple mating behaviour translates into multiple genetic paternity in rock shrimp, this has been confirmed for crayfish (Walker et al 2002). Thus, we hypothesised that genetic multiple paternity is the mating strategy of the galatheid species investigated.…”

“…This simulation takes into consideration the potential number of sires, degree of paternal skew and brood size analysed under a range of possible mating scenarios across both species. Mating scenarios, which take into consideration equal, moderately skewed and highly skewed male breeding success, were chosen to reflect both information available from crustacean mating system studies (Walker et al 2002, Bilodeau et al 2005, Yue et al 2010) and recommendations by Neff & Pitcher (2002). Allelic frequency population data for Munida rugosa and M. sarsi samples from the same area were available from a parallel study into the population structure of both species, which was carried out within our research group.…”

“…More recently, attention has shifted towards the examination of female behaviour. These studies have addressed questions related to mate selection (Sainte-Marie et al 1997), convenience polyandry (Thiel & Hinojosa 2003) and cryptic female choice (Walker et al 2002, Thiel & Hinojosa 2003.…”

“…With a few exceptions, focusing on brachyuran crabs (Urbani et al 1998, McKeown & Shaw 2008, the majority of other studies on marine crustaceans have reported on the incidence of multiple paternity, e.g. porcelain crab Petrolisthes cinctipes (Toonen 2004), crayfish Orconectes placidus (Walker et al 2002), American lobster Homarus americanus (Gosselin et al 2005) and ghost shrimp Callichirus islagrande (Bilodeau et al 2005). Knowledge of mating strategies is particularly relevant for species subject to intense fishing exploitation.…”