Development, characterisation, inheritance, and cross-species utility of American lobster (Homarus americanus) microsatellite and mtDNA PCR-RFLP markers

Abstract

Effective management of exploited species demands contemporary knowledge of population structure and mating patterns. Genetic markers can prove useful in providing this knowledge. Despite its commercial importance, genetic markers for American lobster (Homarus americanus) are limited. We developed 12 tetra- and 1 trinucleotide microsatellite loci for American lobster that exhibit little stuttering after PCR amplification. Gene diversity of these loci ranged from 0.516 to 0.929. A four-locus multiplex permits rapid genotyping of progeny in parentage experiments with a paternity exclusion probability over the four loci of 97.8%. We examined the loci for conformity to Hardy-Weinberg expectations (HWE) and linkage using individuals from one location and found that four loci deviated from HWE. We also tested inheritance and pairwise linkage using 48 embryos from each of two females. With the exception of two loci that were derived from the same clone and separated by 72 bp, no evidence of linkage was found. We, for the first time, demonstrate the occurrence of multiple paternity in American lobster. We also observed an apparent occurrence of dispermic androgenesis, possibly the first documentation of such an event within a species. Ten of the loci amplified in European lobster (Homarus gammarus), although two were monomorphic and one deviated significantly from HWE. We quantified mitochondrial DNA (mtDNA) sequence variation through the use of PCR amplification of two DNA fragments, followed by digestion with restriction enzymes; eight haplotypes were detected. One of the two fragments amplified in European lobster. Both sets of markers should prove useful for population discrimination purposes, and the microsatellites, in particular the four-locus multiplex, should prove highly amenable to rapidly addressing questions about mating patterns.

Stock structure and seasonal distribution patterns of American lobster, Homarus americanus, inferred through movement analyses

“…The greater movement variability among individuals originating in central LFA 25 is consistent with the hypothesis of a slight genetic separation at the population level (de Meeus et al, 1993;McLean and Taylor, 2001), although environmental factors are likely to contribute substantially (or totally) to this difference (Shaklee and Bentzen, 1998). Throughout the range of the American lobster, there is evidence for the existence of sub-populations attributable to morphological differences among geographical regions (Harding et al, 1993;Jones et al, 2003) as well as increased incidences of multiple paternity in heavily fished populations (Gosselin et al, 2005). However, for the Southern Gulf of St. Lawrence, studies of morphology, larval dispersal, allozymes, fishery landing patterns and population genetics all suggest that the lobster population in this region can be considered homogeneous (Tracey et al, 1975;Harding et al, 1997).…”

Pleistocene glaciation events shape genetic structure across the range of the American lobster, Homarus americanus

“…Isozyme (Tracey et al . 1975; Shaklee 1983), mitochondrial DNA (Kornfield & Moran 1989; Jones et al . 2003) and random amplified polymorphic DNA (RAPD) (Harding et al .…”

“…1997) approaches have previously been used to investigate population genetic structure of H. americanus and have all found comparatively low levels of genetic variability in this species. Microsatellite DNA markers, which are potentially more informative to quantify genetic diversity and to describe patterns of population structure, have recently been developed for the American lobster (Tam & Kornfield 1996; Jones et al . 2003; Hodgins‐Davis et al .…”

“…2007) but have not previously been applied over a large geographical scale. Jones et al . (2003) and Gosselin et al .…”

“…1987; Hewitt 2000). Given the low variability in mtDNA observed in H. americanus (Jones et al . 2003), typical of many marine species (Avise 2000), we have chosen to use microsatellite DNA markers to examine the large‐scale population structure of lobsters throughout eastern North America.…”