Sexually extravagant males age more rapidly

Area of Science:

• Evolutionary biology
• Gerontology
• Animal behavior

Background:

• Evolutionary theories suggest reproductive investment accelerates aging.
• Males often invest heavily in costly sexual traits and behaviors.
• Empirical evidence linking sexual trait expression to senescence in males is limited.

Purpose of the Study:

• To investigate if male investment in sexual displays causes physiological decline and senescence.
• To examine the relationship between male 'showiness,' reproductive investment, and aging in houbara bustards.
• To explore potential trade-offs between early-life reproductive effort and later-life fertility.

Main Methods:

• Studied long-lived houbara bustards (Chlamydotis undulata).
• Quantified male investment in extravagant sexual displays.
• Assessed senescent deterioration of spermatogenic function in relation to display investment.
• Controlled for selective disappearance of competitive phenotypes.

Main Results:

• Males with higher investment in sexual displays showed more rapid senescent deterioration of spermatogenic function at a younger age.
• The relationship between male display investment and fertility reversed in later life.
• Results were inconsistent with selective disappearance of phenotypes and supported an early vs. late life trade-off.

Conclusions:

• Male sexual selection and investment in costly displays can drive senescence.
• An early vs. late life trade-off in male reproductive competence may significantly influence aging rates.
• Sexual selection is a potentially significant factor in explaining the pace of aging.