Children of the same age can differ remarkably in terms of physical appearance and performance. These individual differences arise from various sources such as genetics, upbringing and environment which can be carried over into adulthood. The same can be seen for various traits in other vertebrate species.

For polygynous males, specific individual traits and performances are crucial for ensuring breeding success. A new publication in the journal Oikos, led by MIMMP’s recent PhD graduate, Kyle Lloyd, examined individual differences (heterogeneity) among pre-breeding male southern elephant seals at Marion Island using 34-years of mark-recapture data.

Pre-breeders expressed individual differences in survival and recruitment for most age classes, likely related to density-dependent effects experienced during early life. These stark differences in pre-breeder vital rates illustrate that the majority of dominant breeders were likely robust in quality during development. Few frail pre-breeders ever obtained social dominance as adults.

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