Effects of aging on timing of hibernation and reproduction

Claudia Bieber,Thomas Ruf,Christopher Turbill

doi:10.1038/s41598-018-32311-7

Claudia Bieber, Thomas Ruf + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-32311-7

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Abstract

Small hibernators are long-lived for their size because seasonal dormancy greatly reduces predation risk. Thus, within a year, hibernators switch between states of contrasting mortality risk (active season versus hibernation), making them interesting species for testing the predictions of life-history theory. Accordingly, we hypothesized that, with advancing age and hence diminishing reproductive potential, hibernators should increasingly accept the higher predation risk associated with activity to increase the likelihood of current reproductive success. For edible dormice (Glis glis) we show that age strongly affects hibernation/activity patterns, and that this occurs via two pathways: (i) with increasing age, dormice are more likely to reproduce, which delays the onset of hibernation, and (ii) age directly advances emergence from hibernation in spring. We conclude that hibernation has to be viewed not merely as an energy saving strategy under harsh climatic conditions, but as an age-affected life-history trait that is flexibly used to maximize fitness.

Highlights

Small hibernators are long-lived for their size because seasonal dormancy greatly reduces predation risk
The prediction from our model showed an increasing probability to invest into reproduction in males, from 0.31 at age 1 to 0.85 at age 10, and in females from 0.03 at age 1 to 0.64 at age 10
The probability of reproduction increased with increasing age, and reproductively active animals of both sexes delayed the onset of hibernation significantly

Summary

Introduction

Small hibernators are long-lived for their size because seasonal dormancy greatly reduces predation risk. Certain traits that reduce mortality risk, such as flight, arboreality or eusociality, can lead to the evolution of relatively slow life histories even in small mammals[2,3,4]. Hibernators are often well hidden in underground burrows, motionless, cold, and with minimal release of odour[7], which increases their average monthly survival to nearly 100%6,8–10 In accordance with their higher annual survival rates, small hibernators reproduce at a slow rate with long generation times, and exhibit life histories comparable to mammals of much larger size, e.g., small ungulates[6,11]. Date leads to an increased body mass prior to hibernation in juveniles[34,35,36], which increases their probability to survive the first hibernation

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