Chapter 4: Swords or Pistols? A Biological Guide to Fighting by: Kelsey Barker, Jose Bonilla and Brittnae Stewart

Introduction In nature, fighting is not always the answer. Knowing when to fight, when to run, or when to throw sand in your opponent’s face is the key to evolutionary success.

“Fight when you have nothing to lose” Fig wasps 1 Live inside figs. Males don’t have wings, so the only time to mate is right after hatching. Live inside figs. Males don’t have wings, so the only time to mate is right after hatching. Two types of fig wasps Two types of fig waspsPollinators Fighters (parasitic) Lovers, generally die before mating Lovers, generally die before mating Fighters, will fight to death and winner gets to mate Fighters, will fight to death and winner gets to mate

“Fight when you have nothing to lose” – Other examples Gladiator frogs 1 – Have sharp, retractable spine which they only use to fight other frogs. Aim is for eyes and eardrums. Gladiator frogs 1 – Have sharp, retractable spine which they only use to fight other frogs. Aim is for eyes and eardrums. Reason for this is that they have a short life span and rarely live from one breeding season to the next, so there exists a lot of competition. Reason for this is that they have a short life span and rarely live from one breeding season to the next, so there exists a lot of competition.

“Fight when you have nothing to lose” – Other examples “Annual” fishes of Africa and South America 1 – live in puddles until they dry up. “Annual” fishes of Africa and South America 1 – live in puddles until they dry up. Once the puddles dry up, only their eggs survive. Once the puddles dry up, only their eggs survive. This creates a struggle to reproduce and facilitates aggressive male competition. This creates a struggle to reproduce and facilitates aggressive male competition.

“Don’t fight if you know you’re going to lose” African elephant 1 Go into musth, anger and lust at the same time Go into musth, anger and lust at the same time Females prefer older, stronger males Females prefer older, stronger males The bigger an elephant is, or the more aggressive it acts, the higher the likelihood that it will win a fight The bigger an elephant is, or the more aggressive it acts, the higher the likelihood that it will win a fight Males often avoid each other during this time, so as to save themselves the struggle of fighting Males often avoid each other during this time, so as to save themselves the struggle of fighting

Two-spotted spider mites 1 – protects female until female molts, whenever fights start, smaller male usually retreats Two-spotted spider mites 1 – protects female until female molts, whenever fights start, smaller male usually retreats Flies measure length between eye stalks, the fly with the shorter stalk usually retreats Flies measure length between eye stalks, the fly with the shorter stalk usually retreats “Don’t fight if you know you’re going to lose” – Other examples

Lobsters engage in fights to establish dominance relationships, and they often remember who they have fought with Lobsters engage in fights to establish dominance relationships, and they often remember who they have fought with

“Fight dirty when you can” Xylocoris maculipennis (pirate bug) 1 Can jab penis through another males body wall in order to inject sperm into other male Can jab penis through another males body wall in order to inject sperm into other male This is possible, but unlikely. Scientists are still researching This is possible, but unlikely. Scientists are still researching

“Fight dirty when you can” – Other examples Moniliformis dubis 1 (spiny-headed worm) finishes mating with female and caps off genitalia with “cement” chastity belt; also does so with males Moniliformis dubis 1 (spiny-headed worm) finishes mating with female and caps off genitalia with “cement” chastity belt; also does so with males Male African bat bedbugs 1 have false sperm receptors, so can trick males into depositing their sperm, thus making their rivals waste valuable sperm Male African bat bedbugs 1 have false sperm receptors, so can trick males into depositing their sperm, thus making their rivals waste valuable sperm

“Feel free to sabotage others to further your mating chances” Three-spine stickleback 1 Males steal eggs for own nest Males steal eggs for own nest Makes male look better to others – more females will want to leave their eggs with him Makes male look better to others – more females will want to leave their eggs with him Will lessen chances of other male to get more eggs Will lessen chances of other male to get more eggs

“Feel free to sabotage others to further your mating chances” – Other Examples Bowerbirds 1 – vandalize or destroy each others bowers Bowerbirds 1 – vandalize or destroy each others bowers

Cheat Sheet for fighting 1. Will this be your only chance to mate? If yes, proceed to question 2 2. If you fight now, will it help you become successful in mating with more females? If yes, proceed to question 3 3. Are you the biggest? Do you have a good chance of winning If yes, FIGHT!!!

Remember, when you’re fighting, bigger almost always means better, running does not mean you’re a coward, watch closely for cheaters, and don’t be above cheating yourself

Bibliography 1. Judson, Olivia. Dr. Tatiana’s Sex Advice to All Creation. New York: Henry Hold and Company, Kravitz, Edward, PhD. Fighting Lobsters and Fighting Flies: Two Model Systems for the Study of Aggression. arch.html May 25, arch.html arch.html