Asian elephants exhibit post-reproductive lifespans

• Published in: BMC Evolutionary Biology
• Main Authors: Simon N. Chapman, John Jackson, Win Htut, Virpi Lummaa, Mirkka Lahdenperä
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2019
• Subjects: Asian elephant; Demography; Fertility; Long-term data; Post-reproductive life; Reproductive cessation; Evolution; QH359-425; toothed whale
• Online Access: https://doi.org/10.1186/s12862-019-1513-1; https://doaj.org/article/4f39265868ba4a359729f668a7e87813

Abstract Background The existence of extended post-reproductive lifespan is an evolutionary puzzle, and its taxonomic prevalence is debated. One way of measuring post-reproductive life is with post-reproductive representation, the proportion of adult years lived by females after cessation of reproduction. Analyses of post-reproductive representation in mammals have claimed that only humans and some toothed whale species exhibit extended post-reproductive life, but there are suggestions of a post-reproductive stage for false killer whales and Asian elephants. Here, we investigate the presence of post-reproductive lifespan in Asian elephants using an extended demographic dataset collected from semi-captive timber elephants in Myanmar. Furthermore, we investigate the sensitivity of post-reproductive representation values to availability of long-term data over 50 years. Results We find support for the presence of an extended post-reproductive stage in Asian elephants, and that post-reproductive representation and its underlying demographic rates depend on the length of study period in a long-lived animal. Conclusions The extended post-reproductive lifespan is unlikely due to physiological reproductive cessation, and may instead be driven by mating preferences or condition-dependent fertility. Our results also show that it is crucial to revisit such population measures in long-lived species as more data is collected, and if the typical lifespan of the species exceeds the initial study period.