PARENT SESSION
Wednesday, August 9, 1:30-5:00 pm
COS 72 - Prey preference and prey defense mechanisms
Plantation Room, Cook Convention Center
Presiders: G Wang and S Raghu

A theoretical model and a behavioral experiment of asymmetric predation.

Nakajima, Mifuyu^*,1, Abrams, Peter², Yodo, Taiga³, Matsuda, Hiroyuki⁴, ¹ University of Tokyo, Japan, Tokyo, Japan² University of Toronto, Canada, Toronto, Canada³ Mie University, Japan, Mie, Japan⁴ Yokohama National University, Japan, Yokohama, Japan

ABSTRACT- Two morphological types (righty and lefty) have been discovered in several fish species, and referred to as a typical example of antisymmetry. A righty (lefty) individual has its right (left) joint of the lower jaw frontward, ventral, and outside compared to its left (right) joint, so its mouth opens leftward (rightward), and its head faces leftward (rightward). It is suggested that: (1) this dimorphism is inheritable in a Mendelian one-locus-two-allele fashion with lefties dominant; (2) frequencies of laterality in each species fluctuate around 0.5; (3) predators mainly exploit prey of the opposite laterality, i.e., lefty and righty predators prey on righties and lefties, respectively, of the prey population. This is defined as "cross predation", and the antonym "parallel predation" means predation of the same laterality type. To investigate the evolution of predation asymmetry, we use a mathematical model which describes competition between two specialists and one generalist: "specialist" which preys specifically on the opposite type prey, and "generalist" which consumes any type of prey. We also examine the cause of asymmetric predation focusing on the effect of body asymmetry on behaviors during predation. Our angling experiment with largemouth bass, Micropterus salmoides, showed their biased behaviors correlated to laterality: righty (lefty) individuals, which faced leftwards (rightwards) had more hooks set on the right (left) side of their mouth than the other side. This suggests that righty (lefty) jerked leftwards (rightwards) when hooked. Since laterality is also observed in prey species, it might affect their behaviors of predation avoidance.→™

Key words: predation, fish, aquatic system