Assessing the role of genetic relatedness in white shark aggregations in Southern Australia

Résumé fourni par la source

Animal aggregation behaviours are often influenced by resource availability, reproduction, and predator avoidance, and to a less extent kinship. The Neptune Islands, located 60-70km off South Australia, hosts one of Australia’s largest adult white shark (Carcharodon carcharias) aggregations sites, where shark abundances peak during the winter alongside prey abundance. However, non-random associations among individuals, forming four distinct communities differing in sex composition and visitation timing, suggest that factors beyond prey abundance may influence aggregation. This study tested whether genetic relatedness contributes to the co-occurrence and visitation patterns of white sharks at the Neptune Islands, a question not previously examined for this species. To achieve this, we genotyped 147 individual white sharks using reduced-representation sequencing, generating >8,000 single nucleotide polymorphisms (SNPs), after which pairwise relatedness was estimated using co-ancestry coefficients and likelihood-based methods, and correlations with location, residency, and seasonality were assessed. Overall, relatedness among shark pairs was low, with no significant associations between genetic relatedness and spatial or temporal visitation patterns. These findings indicate that kinship does not drive aggregation in Australian white sharks, highlighting the need to investigate alternative ecological or social mechanisms underlying their aggregatory behaviour to inform management of this key marine predator.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.