Divergent visual signals and associated mate preferences are frequently hypothesized to result in behavioral isolation between species lineages. Females are traditionally predicted to be the choosier sex, using visual cues such as male color to facilitate mate recognition and assessment. However, a number of authors have hypothesized that males also are selective in choosing mates and that male preferences can be important in maintaining behavioral isolation. Darters of the genus Etheostoma (Percidae) are a diverse group of sexually dimorphic fishes in which males of most species exhibit elaborate nuptial coloration during spawning seasons. Male coloration is hypothesized to play a role in maintaining behavioral isolation between darter species, and females show association preferences for conspecific male coloration. However, the degree to which males exhibit preferences for conspecific female visual cues is less clear. We examined conspecific association preferences based only on visual signals in male Redband Darter, Etheostoma luteovinctum. We presented individuals with a choice of a conspecific female or a female E. hopkinsi, a heterospecific that is almost completely behaviorally isolated from E. luteovinctum and differs in coloration and body shape. Males exhibited a statistically significant association preference for conspecifics in dichotomous choice trials where only visual cues were available. This is the first study to document a significant conspecific association preference in males of a darter species, providing evidence that males may contribute to behavioral isolation from E. hopkinsi. Differences in female coloration, body shape, or behavior appear to serve as important signals that would help maintain behavioral isolation between E. luteovinctum and E. hopkinsi upon secondary contact.

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