Birth weight and neonatal survival of harbour seal pups are positively correlated with genetic variation measured by microsatellites

Abstract

We examined the relations between ¢tness-related traits of wild harbour seal (Phoca vitulina) pups with microsatellite heterozygosity, and with a measure of genomic diversity based on the mean squared distance between microsatellite alleles within an individual, mean d 2 . Birth weight was positively in£uenced by maternal age, pup sex, and either mean d 2 or individual heterozygosity in separate multiple regression models. The association of birth weight with mean d 2 was stronger than that with heterozygosity, however. The factors maternal age, pup sex, and mean d 2 combined to account for 36.8% of the variation in birth weight, with mean d 2 accounting for the greatest explanatory power (52.3% of the variance explained). Pups which survived until weaning had signi¢cantly higher mean d 2 than pups which died, independent of birth weight. These e¡ects are consistent with heterosis resulting from recent population mixing, and/or inbreeding depression in this population. Mean d 2 thus provides (i) a better measure of individual genetic variability than heterozygosity for microsatellite data; and (ii) a convenient tool for assessing the e¡ects of inbreeding and outbreeding in natural populations.

Genomic signatures of population bottleneck and recovery in Northwest Atlantic pinnipeds

“…Samples from this region have been occasionally incorporated into worldwide or ocean basin analyses (Cammen et al., 2011; Klimova et al., 2014; Stanley et al., 1996), but within the Northwest Atlantic, most seal genetics studies have focused on a single colony (Coltman, Bowen, & Wright, 1998; Worthington Wilmer, Allen, Pomeroy, Twiss, & Amos, 1999). One of only two published regional analyses of gray seals in the Northwest Atlantic used mitochondrial and microsatellite markers to study population structure and recolonization and reported panmixia and migration from Canadian source populations to the growing colonies in the Northeast United States (Wood et al., 2011).…”

Heterozygosity and lungworm burden in harbour seals (Phoca vitulina)

“…The publication of the measure mean d-squared, an estimator of microsatellite allele similarity, and the demonstration that it predicts aspects of fitness in deer and seals (Coltman et al, 1998;Coulson et al, 1998) stimulated renewed interest in the link between heterozygosity and fitness (David, 1998). Subsequent studies have developed both new and more effective measures for estimating heterozygosity (Coltman et al, 1999;Amos et al, 2001;Aparicio et al, 2006) and confirmed that panels of as few as 10 presumed neutral microsatellite markers often reveal statistically significant correlations with fitness.…”

“…Subsequent studies have developed both new and more effective measures for estimating heterozygosity (Coltman et al, 1999;Amos et al, 2001;Aparicio et al, 2006) and confirmed that panels of as few as 10 presumed neutral microsatellite markers often reveal statistically significant correlations with fitness. Over the last decade, the list of fitness traits found to be associated with heterozygosity has expanded greatly, from the initial analyses based on juvenile survival (Coltman et al, 1998), now to cover parasite susceptibility (Coltman et al, 1999), reproductive success (Slate et al, 2000;Hoffman et al, 2004) and even behavioural traits, such as territory size (Seddon et al, 2004). Such apparent ubiquity makes these heterozygosity-fitness correlations (HFCs) a potentially important component of natural selection and suggests that understanding their prevalence and basis could help elucidate a number of evolutionary processes.…”

Genetic variability and viral seroconversion in an outcrossing vertebrate population

“…Much of the work that forms the basis for our understanding of relationships between genetic variability and parasitism derives from contrasting highly inbred individuals or populations with outbred (control) individuals or populations, captive experiments or from island populations or populations that have gone through bottlenecks [4][5][6][7][8][9]20,21]. These studies show that extreme loss of variability is associated with increased susceptibility to parasites.…”