Offspring sex ratio increases with paternal reproductive success in a colony of southern elephant seals

• Published in: Marine Mammal Science
• Main Authors: Allegue, Hassen, Guinet, Christophe, Patrick, Samantha, C, Ribout, Cécile, Bichet, Coraline, Lepais, Olivier, Réale, Denis
• Other Authors: Université du Québec à Montréal = University of Québec in Montréal (UQAM), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), School of Environmental Sciences Liverpool, University of Liverpool, Biodiversité, Gènes & Communautés (BioGeCo), Université de Bordeaux (UB)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: Mirounga leonina; offspring sex ratio; polygyny; reproductivesuccess; [SDE]Environmental Sciences; Elephant Seals; Southern Elephant Seals
• Online Access: https://hal.inrae.fr/hal-04640059; https://hal.inrae.fr/hal-04640059/document; https://hal.inrae.fr/hal-04640059/file/Marine%20Mammal%20Science%20-%202024%20-%20Allegue%20-%20Offspring%20sex%20ratio%20increases%20with%20paternal%20reproductive%20success%20in%20a%20colony%20of.pdf; https://doi.org/10.1111/mms.13108

International audience In polygynous species, male reproductive success is often determined by their ability to dominate female harems. Harem‐holders sire a disproportionate number of offspring. Male dominance tends to correlate with age, but intense competition and early male mortality limit most males from achieving high social status. To maximize reproductive success despite low rank, offspring sex ratio adjustment may have evolved, favoring the sex with higher fitness. If traits influencing dominance are heritable and confer reproductive advantages, we expect fathers with higher reproductive success to produce more sons, as they are more likely to become dominant. In contrast, subordinate males with lower success may benefit from siring more daughters. We tested this hypothesis on a colony of southern elephant seals breeding on the Kerguelen Archipelago. We used genetic markers to link the paternity of 540 pups to 58 breeding males. We found that the probability of siring a son increases from 43% to 54% with paternal relative reproductive success, supporting the offspring sex ratio adjustment hypothesis. Given that various factors influence sex ratio in a population, future studies should tease apart these ecological processes (e.g., paternal dominance, maternal condition, local density, or adult sex ratio) and investigate how they interact with each other.