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Associate Professor Takeshi Takegaki of the Graduate School of Fisheries Science and Environmental Studies demonstrated Mate Choice Copying in a Marine Fish

Nagasaki University Graduate School of Fisheries Science and Environmental Studies industry-government-academia partnership researcher Yukio Matsumoto (now with the Fisheries Research Agency) and Associate Professor Takeshi Takegaki demonstrated that female mate choice copying ? copying the mate choice of other females when choosing males to mate with ? occurred in Rhabdoblennius nitidus, a small marine fish, and that this tactic resulted in increased survival rates for their offspring.

In general, females assess the quality of male sexual traits and their reproductive resources to mate with partners with a high potential for reproductive success, inheriting the sexual trait of the males and the preferences of the females onto the next generation.

However, females adopting copying tactic choose the males which mated with other females, regardless of their own genetically-based preferences. Therefore, this mating tactic has recently attracted much attention of behavioral ecologists studying various animals as an important phenomenon affecting the evolution of male sexual traits.

This study is one of the very few studies demonstrating female mate choice copying and its adaptive significance in the wild.

Rhabdoblennius nitidus is a small marine fish, approximately 6cm long, that lives in the shallow waters around southern Japan. In Nagasaki, where the research was conducted, from early summer to late fall multiple females visit nests occupied by males and breed.

In the field experiments, parental phase males, who normally would not be chosen by females, were manipulated to mate with a female (demonstrator female), and this mating behavior was done in the view of other females in the surrounding area.

The females who observed the demonstrator female's spawning repeatedly gathered around the nest of the male (normally unpreferred male) that had spawned with the demonstrator female (Figure 1), and engaged in spawning themselves, despite the fact that there were other males nearby that they normally would have chosen for mating.

In other words, the females copied the mate choice of other females, and spawned with males that normally would not be chosen.

The males of this species usually tend their eggs in the nest until the eggs hatch.

Tending en masse a large number of eggs laid by multiple females is efficient, so males sometimes abandon eggs when only a small number of eggs are tended.

It is therefore a successful strategy for females to lay their eggs where many eggs have already been laid in order to better ensure successful care of eggs until hatching.

The females therefore appear to observe (confirm) the laying of eggs by other females, and lay their own eggs in the same nest, producing nests with large numbers of eggs (Figure 2).

Further research is planned into the background by which the mate choice copying evolved, and its impact on the evolution of sexual traits in Rhabdoblennius nitidus males.

These research results were published in the July 5, 2013 online bulletin of the British academic journal "Animal Behaviour".