Successful cheaters can reverse selection so big weapons collapse

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 (#corroborates, via linked claim)

In the end, the fate of all weapons comes back to benefits and costs. Early in arms races the payoffs for big weapons may soar. But circumstances change. Costs climb and cheaters invade, gouging profits until big weapons reach a point that’s unsustainable: the rewards no longer justify the expense. From that point forward, they’re just a liability. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 457 (#corroborates, via linked claim)

Categorization

• XREF: connects to: Weapon escalation ends when costs outweigh benefits and cheaters invade — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 457; Balancing selection normally curbs weapon size until some lineages escape into runaway arms races — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 22; Cheating males erode the reproductive payoff of weapons, capping their evolution — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 851 (+8 more)

Related

• Cheating males erode the reproductive payoff of weapons, capping their evolution (similarity 0.95)
• Weapon escalation ends when costs outweigh benefits and cheaters invade (similarity 0.93)
• 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)
• When balancing selection fails, bigger weapons win every round and escalate the race. (similarity 0.89)
• Sexual selection drives weapons to extremes because payoffs for winners are enormous. (similarity 0.89)
• Balancing selection normally curbs weapon size until some lineages escape into runaway arms races (similarity 0.88)
• Bigger weapons usually fail because their costs outweigh their benefits (similarity 0.87)
• Deterrence amplifies the evolutionary payoff of extreme weapon size. (similarity 0.86)
• Reproductive success, not survival, drives the largest animal weapons (similarity 0.86)
• Extreme weapon size faces stabilizing, not open-ended, selection in real populations (similarity 0.86)
• Monopolized reproduction drives males of many species to cheat (similarity 0.85)
• Balanced selection keeps most animal weapons modest rather than extreme. (similarity 0.85)
• Arms races inevitably stall as weapon costs neutralize reproductive benefits (similarity 0.85)
• Weapon size in animal species is under stabilizing selection, not open-ended directional selection (similarity 0.85)

Broader Connections

• Cheating males erode the reproductive payoff of weapons, capping their evolution #corroborates (0.80) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 851
• Weapon escalation ends when costs outweigh benefits and cheaters invade #corroborates (0.70) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 457
• Extreme weapon size faces stabilizing, not open-ended, selection in real populations #complicates (0.70)
• Balancing selection normally curbs weapon size until some lineages escape into runaway arms races #corroborates (0.65) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 22
• Deception in warfare escalates against counter-deception at heavy cost #expands (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 454
• Predators evolve counter-tactics that exploit weapon-costly prey #corroborates (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 306
• When balancing selection fails, bigger weapons win every round and escalate the race. #qualifies (0.55)
• Extreme skew in mating success drives arms-race escalation in weaponry #expands (0.55)
• Weapon evolution and deterrence form a self-accelerating spiral. #complicates (0.55) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 390
• Sexual selection drives weapons to extremes because payoffs for winners are enormous. #complicates (0.50)