Where are the beachmasters? Unexpectedly weak polygyny among southern elephant seals on a South Shetland Island. (24th November 2021)

• Record Type: Journal Article
• Authors: Nichols, H. J.; Fuchs, B.; Paijmans, A. J.; Lewis, G.; Bonin, C. A.; Goebel, M. E.; Hoffman, J. I.
• Is Part Of: Journal of zoology. Volume 316:Number 2(2022)
• Page Start: 104
• Page End: 117
• Publication Date: 2021-11-24
• Subjects: beachmaster -- mating system plasticity -- Mirounga leonina -- polygyny -- reproductive skew -- Southern elephant seal; Zoology -- Periodicals; Zoologie -- Périodiques; 590.5
• DOI: 10.1111/jzo.12936
• Languages: English
• ISSNs: 0952-8369

Abstract

Abstract: Intraspecific variation in animal mating systems can have important implications for ecological, evolutionary and demographic processes in wild populations. For example, patterns of mating can impact social structure, dispersal, effective population size and inbreeding. However, few species have been studied in sufficient detail to elucidate mating system plasticity and its dependence on ecological and demographic factors. Southern elephant seals ( Mirounga leonina ) have long been regarded as a textbook example of a polygynous mating system, with dominant 'beachmaster' males controlling harems of up to several hundred females. However, behavioural and genetic studies have uncovered appreciable geographic variation in the strength of polygyny among elephant seal populations. We, therefore, used molecular parentage analysis to investigate patterns of parentage in a small satellite colony of elephant seals at the South Shetland Islands. We hypothesised that dominant males would be able to successfully monopolise the relatively small numbers of females present in the colony, leading to relatively high levels of polygyny. A total of 424 individuals (comprising 33 adult males, 101 adult females and 290 pups) sampled over 8 years were genotyped at 20 microsatellites and reproductive success was analysed by genetically assigning parents. Paternity could only be assigned to 31 pups (10.7%), despite our panel of genetic markers being highly informative and the genotyping error rate being very low. The strength of inferred polygyny was weak in comparison to previous genetic studies of the same species, with the most successful male fathering only seven pups over the entire course of our study. Our results show that, even in a species long regarded as a model for extreme polygyny, male reproductive skew can vary substantially among populations. Abstract : Elephant seals are a textbook example of a highly polygynous mating system, with dominant 'beachmaster' males controlling harems of up to several hundred females. We used molecular parentage analysis to investigate patterns of parentage over an 8‐year period in a small satellite colony of southern elephant seals at the South Shetland Islands. We found that polygyny was weaker than in previous genetic studies, with the most successful male being assigned just 7 pups, suggesting that, even in a species long regarded as a model for extreme polygyny, male reproductive skew can vary substantially among populations