Effects of habitat complexity on mating behavior and mating success in a marine fish

The environments animals inhabit vary greatly in structural complexity, both naturally and as a consequence of human disturbance. Structural complexity might affect communication by visual and other means, impair detection of potential partners, and affect sexual selection processes. Previous studies on shallow water fishes suggest that sexual selection can be relaxed when visibility is reduced. Here, we test whether habitat complexity affects mate search, mate choice, and the opportunity for sexual selection in the two-spotted goby, Gobiusculus flavescens, a marine fish with paternal care. In 2×2 m tanks, we established environments with low or high habitat complexity and introduced a mixed-sex group of fish (8 males, 8 females), which were allowed to breed. Two days later, we released additional (focal) ready-to-mate females in the tanks and observed female mate search and mating behaviors of both sexes. For females, habitat complexity negatively affected rate of movement, encounter r...