title: Adaptive prolonged postreproductive life span in killer whales.
abstract: Prolonged life after reproduction is difficult to explain evolutionarily unless it arises as a physiological side effect of increased longevity or it benefits related individuals (i.e., increases inclusive fitness). There is little evidence that postreproductive life spans are adaptive in nonhuman animals. By using multigenerational records for two killer whale (Orcinus orca) populations in which females can live for decades after their final parturition, we show that postreproductive mothers increase the survival of offspring, particularly their older male offspring. This finding may explain why female killer whales have evolved the longest postreproductive life span of all nonhuman animals.
authors.affiliation: Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QG, UK.
authors.forename: Emma A
authors.initials: EA
authors.lastname: Foster
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Franks
authors.forename: Sonia
authors.initials: S
authors.lastname: Mazzi
authors.forename: Safi K
authors.initials: SK
authors.lastname: Darden
authors.forename: Ken C
authors.initials: KC
authors.lastname: Balcomb
authors.forename: John K B
authors.initials: JK
authors.lastname: Ford
authors.forename: Darren P
authors.initials: DP
authors.lastname: Croft
mesh_terms: D000818:Animals; D005260:Female; D008136:Longevity; D008297:Male; D016016:Proportional Hazards Models; D012098:Reproduction; D050685:Whale, Killer / Q000502:physiology*