"Our results highlight how sex-specific traits can drive disparity in mortality rates"
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Trade-offs between foraging reward and mortality risk drive sex-specific foraging strategies in sexually dimorphic northern elephant seals
Sex-specific phenotypic differences are widespread throughout the animal kingdom. Reproductive advantages provided by trait differences come at a cost. Here, we link sex-specific foraging strategies to trade-offs between foraging reward and mortality risk in sexually dimorphic northern elephant seals
(Mirounga angustirostris). We analyse a decadal dataset on movement patterns, dive behaviour, foraging success and mortality rates. Females are deep-diving predators in open ocean habitats. Males are shallow-diving benthic predators in continental shelf habitats. Males gain six times more mass and acquire energy 4.1 times faster than females. High foraging success comes with a high mortality rate. Males are
six times more likely to die than females. These foraging strategies and trade-offs are related to different energy demands and life-history strategies. Males use a foraging strategy with a high mortality risk to attain large body sizes necessary to compete for females, as only a fraction of the largest males ever mate. Females use a foraging strategy with a lower mortality risk, maximizing reproductive success by pupping annually over a long lifespan. Our results highlight how sex-specific traits can drive disparity in mortality rates and expand species’ niche space. Further, trade-offs between foraging rewards and mortality risk can differentially affect each sex’s ability to maximize fitness.
Source: Kienle SS, Friedlaender AS, Crocker DE, Mehta RS, Costa DP. 2022 Trade-offs
between foraging reward and mortality risk drive sex-specific foraging strategies in sexually
dimorphic northern elephant seals. R. Soc. Open Sci. 9: 210522. https://doi.org/10.1098/rsos.210522
Also read this article on The Guardian.
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