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

Early life expenditure in sexual competition is associated with increased reproductive senescence in male red deer 
Jean-François Lemaître, Jean-Michel Gaillard, Josephine M. Pemberton, Tim H. Clutton-Brock and Daniel H. Nussey (2014)
Proceedings of the Royal Society B: Biological Sciences


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.

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"[Although] high reproductive expenditure in early adulthood is associated with an increased rate of decline in late life, this decline is not sufficient to negate the phenotypic superiority of these males until extreme old age."

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Distress about mating rivals

Distress about mating rivals
David M Buss et al.; 2000


Abstract

This research tested the evolutionary psychological hypothesis that men and women would be most distressed about threats from rivals who surpass them on sex-linked components of mate value. Six predictions were tested in samples from three cultures, the United States (N = 208), the Netherlands (N = 349), and Korea (N= 174). Five predictions were supported in all three cultures. Korean, Dutch, and American men, more than corresponding women, report greater distress when a rival surpasses them on financial prospects, job prospects, and physical strength. Korean, Dutch, and American women, in contrast, report greater distress when a rival surpasses them on facial and bodily attractiveness. The cultures differed on some variables. Korean women and men, for example, differed from Americans and Dutch in reporting more distress over rivals who had better financial prospects, better job prospects, and higher status and prestige. Americans exceeded Koreans in reporting distress when rivals had more attractive faces and bodies, whereas Dutch exceeded the other cultures in reporting more distress when rivals had a better sense of humor. Discussion focuses on possible proximate psychological mechanisms underlying distress over rivals and the theoretical importance of intrasexual competition.