In nearly all weaponed species, males carry the weapons, not females.

Evidence

In every way that matters for this book, jacanas are backward. Females are more aggressive than males, they are larger than males, they fight more viciously and frequently than males, and they have larger weapons. Usually it’s the other way around. In flies, beetles, mastodons, crabs, and elk, males are armed, not females. Jacanas excepted, in every species with weapons confined to a single sex, males have those weapons. Why should just one sex have weapons? And why is it (almost) always the males? — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 149

Categorization

• XREF: Connects to sexual selection theory (Darwin, bateman gradients) that this book’s later chapters on weapon evolution will build on. — connects to: Big weapons only benefit males with the reserves to wield them effectively — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 355; Weapon size is favored when males defend resources females need — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 960; Males evolve big weapons to defend resources that females visit

Related

• Among jacanas, females are the armed, aggressive sex defending breeding territories. (similarity 0.88)
• Males evolve big weapons to defend resources that females visit (similarity 0.88)
• Male parental care can invert the direction of sexual selection and weaponry (similarity 0.87)
• Weapon size is favored when males defend resources females need (similarity 0.87)
• Sexual selection can be far stronger than natural selection and drives weapon extremes (similarity 0.85)
• Polygynous male primates evolved larger canines than monogamous ones (similarity 0.85)
• Sexual selection drives weapons to extremes because payoffs for winners are enormous. (similarity 0.84)
• Jacana females only breed when dominant enough to hold territory. (similarity 0.84)
• Big weapons only benefit males with the reserves to wield them effectively (similarity 0.83)
• Only a minority of males can afford to build full-size weapons (similarity 0.83)
• Weapon growth widens the gap between the best- and worst-armed males. (similarity 0.83)
• Reproductive success, not survival, drives the largest animal weapons (similarity 0.83)
• Sexual weapons sometimes protect rather than burden their bearers from predators (similarity 0.83)
• Weapons evolve only when reproductive benefits exceed costs (similarity 0.83)
• Weapon size in animal species is under stabilizing selection, not open-ended directional selection (similarity 0.83)

Broader Connections

• Males evolve big weapons to defend resources that females visit #contradicts (0.35)
• Weapon size is favored when males defend resources females need #contradicts (0.30) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 960