Early life expenditure in sexual competition is associated with increased reproductive senescence in male red deer.

Jean-François Lemaître,Daniel H Nussey,Tim H Clutton-Brock,Josephine M Pemberton,Jean-Michel Gaillard

doi:10.1098/rspb.2014.0792

Abstract

The evolutionary theories of senescence predict that investment in reproduction in early life should come at the cost of reduced somatic maintenance, and thus earlier or more rapid senescence. There is now growing support for such trade-offs in wild vertebrates, but these exclusively come from females. Here, we test this prediction in male red deer (Cervus elaphus) using detailed longitudinal data collected over a 40-year field study. We show that males which had larger harems and thereby allocated more resources to reproduction during early adulthood experienced higher rates of senescence in both harem size and rut duration. Males that carried antlers with more points during early life did not show more pronounced declines in reproductive traits in later life. Overall, we demonstrate that sexual competition shapes male reproductive senescence in wild red deer populations and provide rare empirical support for the disposable soma theory of ageing in males of polygynous vertebrate species.

Highlights

The process of senescence is defined as a progressive deterioration of the physiological function of an organism, leading to a decline in survival or reproductive performance with age [1]
Our findings support the predictions of the disposable soma theory of ageing, which predicts a negative relationship between allocation to reproduction during early life and fitness-related traits in late life [34]
No physiological traits were measured on male red deer on low early harem size high early harem size age the Isle of Rum, the positive trend between time spent fighting and mass loss observed in fallow deer (Dama dama) [36] suggests that, at least in polygynous and size dimorphic deer species, somatic deterioration might be more pronounced in males controlling relatively large harems

Summary

Introduction

The process of senescence is defined as a progressive deterioration of the physiological function of an organism, leading to a decline in survival or reproductive performance with age [1]. We use the exceptionally detailed long-term monitoring of red deer on the Isle of Rum (Scotland) to test whether male expenditure in sexual competition during early life influences reproductive senescence in late life, as predicted by the disposable soma theory.

Results

Conclusion