Territory inheritance in clownfish

Peter M. Buston

Abstract

Animal societies composed of breeders and non–breeders present a challenge to evolutionary theory because it is not immediately apparent how natural selection can preserve the genes that underlie non–breeding strategies. The clownfish Amphiprion percula forms groups composed of a breeding pair and 0–4 non–breeders. Non–breeders gain neither present direct, nor present indirect benefits from the association. To determine whether non–breeders obtain future direct benefits, I investigated the pattern of territory inheritance. I show that non–breeders stand to inherit the territory within which they reside. Moreover, they form a perfect queue for breeding positions; a queue from which nobody disperses and within which nobody contests. I suggest that queuing might be favoured by selection because it confers a higher probability of attaining breeding status than either dispersing or contesting. This study illustrates that, within animal societies, individuals may tolerate non–breeding positions solely because of their potential to realize benefits in the future.