Sibship reconstruction demonstrates the extremely low effective population size of striped bass Morone saxatilis in the Santee–Cooper system, South Carolina, USA

Abstract

For organisms with great fecundity and high mortality in early life stages, such as shellfish or fishes, the need to match reproductive activity with environmental conditions conducive to spawning, fertilization, larval development and recruitment may result in extreme variance in reproductive success among individuals. The main objective of this study was to investigate evidence of large variance in the reproductive success of the striped bass Morone saxatilis in the Santee-Cooper system, South Carolina, USA. Seven microsatellite loci were analysed in 603 recruits representing three yearly cohorts from 1992 to 1994, and a group analysis was performed to identify full-sib families. Large variance in reproductive success was detected, with a few large, full-sib families contributing disproportionately to each of the cohorts. The severity of sweepstakes reproductive success varied among cohorts depending on environmentally imposed mortality. Estimations of the effective number of breeders in these long-lived fish ranged from 24 in 1992 to 44 in 1994. Furthermore, the estimated genetic effective population size (N(e) = 93) is approximately four orders of magnitude lower than estimates of adult census size (N = 362 000). Furthermore, the presence of large full-sib families indicates that striped bass engage in pair mating in the wild. Heterogeneity in genetic composition was also observed among cohorts, suggesting that genetically different adults contribute to different cohorts and that chance rather than fitness variation determines reproductive success.

Siblingship tests connect two seemingly independent farmed Atlantic salmon escape events

“…In the present study, we implemented siblingship tests for the first time, which led to an increase in the accuracy and confidence of assignment of the salmon escapees back to their farm(s) of origin. The identification of the relationships among siblings, either those that share 1 (half sibling) or both (full sibling) parents, has formerly been utilised to address a wide variety of questions in biology and ecology, such as elucidating fine-scale patterns of larval dispersal for a rocky reef fish on the open coast (Schunter et al 2014), determining individual variability in reproductive success (Hudy et al 2008, Liu & Ely 2009 and dispersal (Hudy et al 2008), providing some insight into the mating systems by inferring genotypes of unknown parents (Wang 2004, Kanno et al 2011) and tracing market product to the farm of origin in the event of detection of disease or toxins in the market fish (Hayes et al 2005).…”

Temporal genetic homogeneity among shore crab (Carcinus maenas) larval events supplied to an estuarine system on the Portuguese northwest coast

“…Several cases of temporal genetic heterogeneity among larval or recruit cohorts have been reported previously (Kordos and Burton, 1993;Ruzzante et al, 1996;Li and Hedgecock, 1998;Moberg and Burton, 2000;Pujolar et al, 2006;Liu and Ely, 2009), but such differences can be apportioned to variation in the adult reproductive contribution through random genetic drift within a single population only when immigration is ruled out (Li and Hedgecock, 1998;Liu and Ely, 2009). For instance, temporal variation of megalopal allelic frequencies of the blue crab Callinectes sapidus in the Gulf of Mexico suggested changes in larval source populations throughout the recruitment season that were attributed to seasonal changes in coastal current patterns or to timing differences in spawning season (Kordos and Burton, 1993), rather than to transitory effects of variance in reproductive success.…”

“…According to the sweepstakes hypothesis, relatively few adults in each generation succeed in reproducing, as a result of stochastic processes leading to their reproductive activity coinciding with the correct oceanographic conditions conducive to spawning, fertilization, larval survival and recruitment (Hedgecock, 1994). Sweepstakes reproduction has been described in both invertebrates and fishes (Li and Hedgecock, 1998;Pujolar et al, 2006;Hedgecock et al, 2007b;Liu and Ely, 2009;Christie et al, 2010). Large discrepancies between the effective (N e ) and the census (N) population sizes usually resulting in very low N e /N ratios, are often reported among marine species (reviewed in Hauser and Carvalho, 2008) and are explained mainly by high variance in reproductive success.…”

Coastal upwelling is linked to temporal genetic variability in the acorn barnacle Balanus glandula

“…Lundy et al 2000, Chapman et al 2002, McPherson et al 2003, Dannewitz et al 2005, Burford & Larson 2007, Liu & Ely 2009, Christie et al 2010 to invertebrates (e.g. Colgan 1981, Hedgecock 1994b, David et al 1997, Li & Hedgecock 1998, Johnson & Wernham 1999, Moberg & Burton 2000, Hedgecock et al 2007).…”