Data for: Lack of intergenerational reproductive conflict, rather than lack of inclusive fitness benefits, likely explains absence of post-reproductive lifespan in long-finned pilot whales

Life history theory suggests that individuals should reproduce until
death, yet females of a small number of mammals live for a significant
period after ceasing reproduction, a phenomenon known as post-reproductive
lifespan. It is thought that the evolution of this trait is facilitated by
increasing local relatedness throughout a female’s lifetime. This allows
older females to gain inclusive fitness through helping their offspring
(known as a mother effect) and/or grandoffspring (known as a grandmother
effect), rather than gaining direct fitness through reproducing. However,
older females may only benefit from stopping reproducing when their direct
offspring compete with those of their daughters. Here, we investigate
whether a lack of post-reproductive lifespan in long-finned pilot whales
(Globicephala melas) results from minimal benefits incurred from the
presence of older females, or from a lack of costs resulting from
mother-daughter co-reproduction. Using microsatellite data, we conducted
parentage analysis on individuals from 25 pods and find that younger
females were more likely to have offspring if their mother was present in
their pod, indicating that mothers may assist inexperienced daughters to
reproduce. However, we found no evidence of reproductive conflict between
co-reproducing mothers and daughters, indicating that females may be able
to reproduce into old age whilst simultaneously aiding their daughters in
reproduction. This highlights the importance of reproductive conflict in
the evolution of a post-reproductive lifespan and demonstrates that mother
and grandmother effects alone do not result in the evolution of a
post-reproductive lifespan.