The significance of postreproductive lifespans in killer whales: A comment on Robeck et al.

Robeck et al. (2015) claim that reproductive and actuarial senescence is common in mammalian species and therefore not an unexpected finding in killer whales. However, in most mammals, reproductive and somatic senescence are aligned, and reproduction gradually declines with age. In contrast, there is a substantial evidence that reproductive senescence is unusually accelerated relative to somatic senescence in resident killer whales, resulting in a prolonged postreproductive lifespan. We demonstrate that a postreproductive lifespan is a key component of resident killer whale life history, and is robust to reasonable error in age estimates.