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Should females prefer old males?
Julia Carolina Segami1, Martin I Lind1, Anna Qvarnström1
1Department of Ecology and Genetics, Animal Ecology Uppsala University Uppsala SE-75236 Sweden.
Evolution Letters
|October 8, 2021
Summary
Female birds gain reproductive advantages from mating with older males. However, offspring sired by older males show lower quality, suggesting a trade-off between direct and genetic benefits in mate choice.
Area of Science:
- Evolutionary biology
- Behavioral ecology
- Animal reproduction
Background:
- Mate choice in females involves balancing direct benefits (e.g., resources) with genetic benefits for offspring.
- The impact of male age on offspring quality is debated, with potential trade-offs between germline aging and indicators of superior genes.
Purpose of the Study:
- To disentangle the effects of male age on female reproductive fitness using extra-pair young in collared flycatchers.
- To investigate the opposing direct and genetic benefits associated with mating with older males.
Main Methods:
- Utilized 18 years of long-term data from a natural population of collared flycatchers.
- Analyzed within-pair and extra-pair young to isolate paternal genetic effects from direct benefits.
- Compared offspring quality sired by older versus younger males.
Main Results:
- Females paired with older males experienced overall reproductive advantages.
- Offspring sired by older males were of lower genetic quality compared to extra-pair half-siblings.
- Offspring sired by younger males showed higher quality than their extra-pair half-siblings.
Conclusions:
- Direct benefits from older males may mask negative genetic effects on offspring quality.
- Offspring may benefit from being sired by younger males and raised by older males to maximize both genetic and direct benefits.
- Germline quality may decline with age before other senescence signs appear.
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