Cheating males erode the reproductive payoff of weapons, capping their evolution

Evidence

To use the same basic equation I allude to in the text, the benefits of having big weapons (B), representing the offspring produced by the females they guard, are offset by production, maintenance, and fighting costs (C). When B − C > 0, then selection drives the evolution of weapons toward ever greater size. What’s not shown is our assumption that males are gleaning 100 percent of the fertilizations of the females they defend: (1 * B) − C > 0. Cheating males erode the rewards to dominant males, so that they reap only a fraction of the sired offspring that they otherwise would have. In the hypothetical beetle example where sneak males, on average, steal one-fourth of the fertilizations, the new equation would be: (0.75 * B) − C > 0. Benefits are devalued by the proportion of fertilizations stolen by cheaters (1 − 0.25 = 0.75). At some point, if cheaters steal enough, the realized benefits may be low enough that they no longer exceed the costs, even for the most successful guarding males. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 851

Categorization

• XREF: The cost-benefit balance point and cheater dynamics echo themes in evolutionary game theory and work on cooperation versus defection. — connects to: Extreme skew in mating success drives arms-race escalation in weaponry; Arms races inevitably stall as weapon costs neutralize reproductive benefits — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 432; Successful cheaters can reverse selection so big weapons collapse (+10 more)

Related

• Successful cheaters can reverse selection so big weapons collapse (similarity 0.95)
• Extreme skew in mating success drives arms-race escalation in weaponry (similarity 0.92)
• Weapon costliness keeps signals honest by excluding weaker males (similarity 0.92)
• Weapon escalation ends when costs outweigh benefits and cheaters invade (similarity 0.91)
• Monopolized reproduction drives males of many species to cheat (similarity 0.89)
• Sexual selection drives weapons to extremes because payoffs for winners are enormous. (similarity 0.88)
• Reproductive success, not survival, drives the largest animal weapons (similarity 0.86)
• Sexual selection can be far stronger than natural selection and drives weapon extremes (similarity 0.85)
• Weapons evolve only when reproductive benefits exceed costs (similarity 0.85)
• Bigger weapons usually fail because their costs outweigh their benefits (similarity 0.85)
• Deterrence amplifies the evolutionary payoff of extreme weapon size. (similarity 0.85)
• Balancing selection normally curbs weapon size until some lineages escape into runaway arms races (similarity 0.84)
• Poor-quality males pay steeper costs for large weapons and so invest less (similarity 0.84)
• Competition for reproduction drives evolution of nature’s biggest weapons (similarity 0.84)
• Male combat for mating access frequently causes serious wounds and sometimes death (similarity 0.84)

Broader Connections

• Weapons evolve only when reproductive benefits exceed costs #expands (0.70) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 199
• Competition for reproduction drives evolution of nature’s biggest weapons #qualifies (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 136
• Sexual selection can be far stronger than natural selection and drives weapon extremes #qualifies (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 177
• Deterrence amplifies the evolutionary payoff of extreme weapon size. #complicates (0.50) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 387