Experimental investigations of the evolutionary significance of sexually dimorphic nuptial colouration in Gasterosteus aculeatus (L.): the relationship between male colour and female behaviour

Cladistic analysis of behavioural interactions during a series of female choice trials revealed three groups of reproductively unsuccessful males in a population of anadromous Gasterosteus aculeatus: inactive losers (losing male did not participate in choice test), active losers (losing male active during choice test), and fighting losers (subgroup of active losers defined by the observation that the female did not immediately follow the first male to approach her). The inactive losers group represents a "no choice" situation. In the remaining two groups, females responded preferentially to the most intensely coloured member of the competing male pair. This preferential response was strongest during the prechoice, captive presentation where the majority of females oriented head-up to, and tracked, the brighter red male. Once released, the female's initial response to the brighter courtship signal was overridden by the behavioural actions of the duller intensity male in 4 out of 12 trials. Although two of ...