Male parental care can invert the direction of sexual selection and weaponry

Evidence

Female jacanas still produce the larger gametes (eggs are bigger than sperm), and it takes them a few weeks to recover between clutches. But this is where female investment stops. Male jacanas spend up to three months tending to eggs and chicks and, as a result, their turnaround time is longer than the females’ (seventy-eight days, on average, compared with twenty-four). At any point in time, roughly half of the males in a population are tied down with existing eggs or chicks, leaving just a few of them free to start new broods, while most of the females are yolked up and ready to go. They could lay eggs immediately if only they had access to a territory-holding, reproductively ready male. In jacanas, there simply are not enough receptive males to go around, and females battle it out for the chance to breed. Sexual selection, rather than selection from predators or prey, drove the evolution of blazing yellow spurs in jacana females. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 160

Categorization

• XREF: The jacana case is the animal mirror-image of the human reversal toward female-competition and should be held against the human knights account. — connects to: Sexual selection can be far stronger than natural selection and drives weapon extremes — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 177; Extreme skew in mating success drives arms-race escalation in weaponry; Males evolve big weapons to defend resources that females visit (+5 more)

Related

• Polygynous male primates evolved larger canines than monogamous ones (similarity 0.90)
• In nearly all weaponed species, males carry the weapons, not females. (similarity 0.87)
• Among jacanas, females are the armed, aggressive sex defending breeding territories. (similarity 0.85)
• Jacana females only breed when dominant enough to hold territory. (similarity 0.84)
• Males evolve big weapons to defend resources that females visit (similarity 0.83)
• Sexual selection can be far stronger than natural selection and drives weapon extremes (similarity 0.82)
• Sexual selection drives weapons to extremes because payoffs for winners are enormous. (similarity 0.81)
• Extreme skew in mating success drives arms-race escalation in weaponry (similarity 0.80)
• Male combat for mating access frequently causes serious wounds and sometimes death (similarity 0.80)
• Reproductive success, not survival, drives the largest animal weapons (similarity 0.79)
• Weapon size is favored when males defend resources females need (similarity 0.79)
• Sexual selection stays directionally constant while physical natural selection oscillates (similarity 0.79)
• Social competition environments evolve in tandem with weapons, unlike fluctuating physical environments (similarity 0.79)
• Parentage certainty drives why females, not males, typically provide parental care (similarity 0.79)
• Higher female reproductive investment explains why females usually provide offspring care. (similarity 0.79)

Broader Connections

• Males evolve big weapons to defend resources that females visit #qualifies (0.70)
• Weapon size is favored when males defend resources females need #qualifies (0.65) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 960
• Sexual selection can be far stronger than natural selection and drives weapon extremes #corroborates (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 177
• Sexual selection stays directionally constant while physical natural selection oscillates #contradicts (0.60) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 185
• Extreme skew in mating success drives arms-race escalation in weaponry #corroborates (0.55)