Where have all the fathers gone? An extensive microsatellite analysis of paternity in the grey seal (Halichoerus grypus)

Abstract

Microsatellites were used to conduct an extensive analysis of paternity of grey seals from two Scottish breeding colonies at North Rona (n = 1189) and the Isle of May (n = 694), spanning more than a decade. A maximum of 46% of pups at North Rona and 29% of pups at the Isle of May could be allocated a father, even though the majority of candidate males for specific study sites within each colony were believed to have been sampled. Based on the paternities which could be assigned, both colonies showed evidence of reproductive skew, apparently due to the presence of approximately five males who were exceptionally successful. Some males were assigned paternities at least 10 years before, and colleagues 10 years after, being sampled, implying a reproductive lifespan of at least 10 years, and there are indications that the real maximum lies in the range 15-20 years. Male grey seals appear to have at least two breeding strategies they can adopt. On land, some males benefit from a traditionally polygynous system. However, between 50 and 70% of grey seal pups born at a particular colony are not fathered by males who are likely to be sampled by us, implying that these males seldom venture ashore here. We conclude that aquatic mating may play a much larger role in the grey seal than has previously been thought.

Genomic signatures of population bottleneck and recovery in Northwest Atlantic pinnipeds

“…Yet, we know from prior studies that gray seals exhibit a polygynous mating system with relatively high reproductive skew (Worthington Wilmer et al., 1999), violating the first assumption. Furthermore, given the assumption of neutrality, it is unsurprising that the model does not have the capacity to accurately estimate outlier loci that change in allele frequency more than expected over the sampled study period.…”

“…The differences may also be due to the wider geographic range sampled for gray seals in comparison with harbor seals, but our findings of no significant structure or differences in diversity between gray seal colonies do not strongly support this potential explanation. Although differences in species diversity have not been previously observed in microsatellite markers assessed in both species (Goodman, 1998; Worthington Wilmer et al., 1999), one study of genetic diversity at the immune gene complex, MHC class I, in gray and harbor seals reports preliminary findings of greater diversity in gray seals in a small number of individuals (Hammond, Guethlein, Norman, & Parham, 2012). If harbor seals are truly less genetically diverse than gray seals at immune markers and/or more broadly across the genome, this may, in part, explain general observations of lower disease resistance among harbor seals than gray seals (Bogomolni, 2014), an avenue of research that requires further investigation of diversity in functional regions of the genome at a population or species‐wide scale.…”

“…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).…”

The breeding biology of lemon sharks at a tropical nursery lagoon

“…Amos et al 1993;Clapham & Palsbøll 1997;Kichler et al 1999;Worthingham Wilmer et al 1999). However, population genetic studies of elasmobranchs have lagged behind other classes of vertebrates (Heist 1999), in part due to low genetic variability seen at allozyme (Smith 1986;MacDonald 1988;Lavery & Shaklee 1989) and mitochondrial DNA loci (Heist et al 1995(Heist et al , 1996.…”

Reconstruction of Parental Microsatellite Genotypes Reveals Female Polyandry and Philopatry in the Lemon Shark, Negaprion Brevirostris

“…As with any large, mobile marine species, the temporal and spatial scopes of shark reproductive behaviors make direct observations challenging. Many aspects of shark mating systems will have to be inferred using genetic techniques, as has been the case for other marine organisms (Kichler et al 1999;Worthingham Wilmer et al 1999). Genetic studies have also been difficult, hampered by the slow development of highly variable mark-ers for elasmobranchs, such as microsatellites, needed for parentage studies.…”