Incomplete behavioural isolation and asymmetric female preference in darter sister species (Percidae: Etheostoma)

Abstract

In this study, female preferences and behavioural isolation were estimated in a pair of allopatric sister species, Etheostoma duryi and Etheostoma flavum. Dichotomous mate preference trials were conducted to determine whether females prefer to associate with conspecific over heterospecific males and free-spawning assays were conducted to determine whether those preferences translated into behavioural isolation. Dichotomous mate choice trials revealed asymmetric female preference, as female E. flavum preferred conspecific males, whereas female E. duryi showed no preference. Free-spawning assays indicated that behavioural isolation remains incomplete between E. duryi and E. flavum (IB = 0·19). In addition to female mating preferences, male behaviour also appeared to influence mating outcomes as male E. flavum consistently courted conspecific females more often in free-spawning assays whereas male E. duryi did not. The data therefore suggest that despite marked divergence in male nuptial colour, divergence in female preferences between these species may not be sufficient to maintain species boundaries upon secondary contact. These results contrast with similar work in a sympatric darter species pair and may be explained by considering the contributions of reinforcement and differences in colour pattern as well as colour value.

Sexually asymmetric colour-based species discrimination in orangethroat darters

“…In E. zonale, E. barrenense and Etheostoma duryi, both males and females preferentially associate with conspecific fish over heterospecific fish (Martin & Mendelson, 2013;Williams & Mendelson, 2010). On the other hand, in Etheostoma flavum, neither males nor females show preferences for conspecific fish (Martin & Mendelson, 2013). A sex difference in species discrimination is present in Etheostoma nigripinne but in the opposite direction to our results: females strongly prefer conspecific males while males do not consistently prefer conspecific females (O'Rourke & Mendelson, 2010).…”

“…Although behavioural isolation is widespread among darters and appears to be the primary mechanism for reproductive isolation (Mendelson, 2003), this pattern has not been reported in other species. In E. zonale, E. barrenense and Etheostoma duryi, both males and females preferentially associate with conspecific fish over heterospecific fish (Martin & Mendelson, 2013;Williams & Mendelson, 2010). On the other hand, in Etheostoma flavum, neither males nor females show preferences for conspecific fish (Martin & Mendelson, 2013).…”

Intrasexual competition underlies sexual selection on male breeding coloration in the orangethroat darter, Etheostoma spectabile

“…The spectacular and diverse male coloration found in many darter species has long been considered to result from sexual selection (Reeves 1907; Mendelson 2003) and has sparked interest in the role that male coloration may have played in facilitating darter speciation (Martin and Mendelson 2013; Williams et al. 2013).…”

Phylogenetic Correlation Between Male Nuptial Color and Behavioral Responses to Color Across a Diverse and Colorful Genus of Freshwater Fish (Etheostoma spp., Teleostei: Percidae)

“…For females, association preferences are assumed to translate to mating preferences, as has been observed in many fish species including darters (Bizazza et al. ; Brooks & Endler ; Aspbury & Basolo ; Lehtonen & Lindström ; Williams & Mendelson ; Jeswiet & Godin ; Martin & Mendelson ). For males, association preferences are assumed to translate to directed agonistic interactions, as in a recent study demonstrating a positive association between interspecific color differences and preferential targeting of conspecific males (Martin & Mendelson, in press).…”