Tunnel-bound fights give longer horns a decisive performance advantage

Evidence

Tunnels are localized and confined—exactly the sort of fixed, economically defensible substrate in which we would expect to find a performance advantage to large weapons. Males stab their horns into the sides of tunnel walls to block entry of intruder males, or use them to twist or pry opponents loose before pushing them up and out of the hole. In these fights, males can lock themselves into position by bracing against the tunnel walls with barbs, teeth, and thick spines on their legs. Anchored, they can bring the leverage of their weapons to full effect, and males with longer horns win these contests. Because mating almost always occurs inside tunnels, winning fights is a critical prerequisite for reproduction. — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 224

Categorization

• XREF: connects to: Tunneling behavior predicts horn evolution in dung beetles — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 713; Tunneling dung beetles guard burrow entrances and evolve horns; rollers do not — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 222; Burrow-guarding constrains fights to duels and drives weapon evolution (+1 more)

Related

• Tunneling dung beetles guard burrow entrances and evolve horns; rollers do not (similarity 0.91)
• Tunneling behavior predicts horn evolution in dung beetles (similarity 0.87)
• Tunnel dwellers fight successive duels and evolve weapons; open-ground species scramble without them. (similarity 0.87)
• Burrow-guarding constrains fights to duels and drives weapon evolution (similarity 0.87)
• Smaller-horned males usually lose escalated dung beetle fights (similarity 0.85)
• No ball-rolling dung beetle species has evolved horns despite constant fighting (similarity 0.82)
• Burrowing is the most common ecology driving extreme weapon evolution. (similarity 0.80)
• Dung beetle horns evolved and were lost repeatedly across their history (similarity 0.80)
• Fortified architecture lets termites negate an enemy’s numerical superiority (similarity 0.79)

Broader Connections

• Burrow-guarding constrains fights to duels and drives weapon evolution #corroborates (0.85)
• Breached fortifications restore numerical advantage to massed attackers in termite warfare #corroborates (0.50) — Emlen, Douglas J, Animal Weapons_ The Evolution of Battle, 490