Extreme polygyny results in intersex differences in age-dependent survival of a highly dimorphic marine mammal
Developmental differences in vital rates are especially profound in polygamous mating systems. Southern elephant seals ( Mirounga leonina ) are highly dimorphic and extremely polygynous marine mammals. A demographic model, supported by long-term capturemarkrecapture records, investigated the influen...
| Published in: | Royal Society Open Science |
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| Main Authors: | , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
The Royal Society Publishing
2023
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| Subjects: | |
| Online Access: | https://doi.org/10.1098/rsos.221635 http://ecite.utas.edu.au/155982 |
| Summary: | Developmental differences in vital rates are especially profound in polygamous mating systems. Southern elephant seals ( Mirounga leonina ) are highly dimorphic and extremely polygynous marine mammals. A demographic model, supported by long-term capturemarkrecapture records, investigated the influence of sex and age on survival in this species. The study revealed clear differences between female and male age-dependent survival rates. Overall juvenile survival estimates were stable around 8085% for both sexes. However, male survival estimates were 510% lower than females in the same age classes until 8 years of age. At this point, male survival decreased rapidly to 50% 10% while female estimates remained constant at 80% 5%. Different energetic requirements could underpin intersex differences in adult survival. However, the species' strong sexual dimorphism diverges during early juvenile development when sex-specific survival rates were less distinct. Maximizing growth is especially advantageous for males, with size being a major determinant of breeding probability. Maturing males may employ a high-risk high-reward foraging strategy to compensate for extensive sexual selection pressures and sex-specific energetic needs. Our findings suggest sex-specific adult survival is a result of in situ ecological interactions and evolutionary specialization associated with being a highly polygynous marine predator. |
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