Can ecotypic differences in male courtship behaviour be explained by visual cues provided by female threespine stickleback?

Background: Research on the evolution of reproductive isolation concentrates on an evaluation of the probability of mating within and between species with little attention to the role of male and female mate choice in the process. Male threespine stickleback, as well as females, select mates but male choice behaviour is poorly understood. Male threespine stickleback use visual cues in courting females, and have been shown to prefer females with more distended abdomens, which may indicate higher fecundity. Question: Do male threespine stickleback from divergent allopatric populations prefer females of their own ecotype using visual cues from live females? Hypothesis: Males will court females of their own ecotype more vigorously than they do females of the other ecotype. Males will also prefer females who are more fecund. Organisms: Allopatric populations of anadromous, benthic, and limnetic threespine stickleback. Methods: We presented males with the opportunity to court two females, one from a benthic population and one from a limnetic population. During 5-min trials, we recorded the following behaviours: zigzags, direct approaches, and the time a male spent following each female. Results: Visual cues were not sufficient to elicit male courtship differences towards females of different ecotypes. However, contrary to expectations, males reduced their courtship toward females with a higher estimated fecundity.