Evidence of an emerging female preference for an artificial male trait and the potential for spread via mate choice copying in Poecilia latipinna

Abstract

The initial purpose of the project described herein was to assess the preference of female Poecilia latipinna for an artificial novel male trait—an orange‐colored distal fringe added to the caudal fin of an otherwise wild‐type conspecific. Analysis of the preliminary data revealed consistent individual differences in the strength of female preference for either orange‐tailed or wild‐type males. This finding inspired the study's second aim—to evaluate whether the preference for orange‐tailed males observed among a subset of females could spread via mate choice copying to others in the population that initially preferred wild‐type males. Two experiments and a control were conducted wherein females were simultaneously presented with an orange‐tailed and a wild‐type dummy male using a standard dichotomous choice design. In the first experiment, female preference was assessed on two separate occasions in order to characterize the variability and consistency in preference for orange‐tailed versus wild‐type males. The second experiment addressed mate choice copying: Female preference was again assessed on two separate occasions, but involved pairing a model female with the non‐preferred male for a period of time between preference tests. A third set of control tests were conducted using the same protocol as the copying experiment except that subject females were unable to see the model paired with the non‐preferred male. Results showed that, although females collectively preferred neither the orange‐tailed nor the wild‐type dummy male in the first round of preference tests, the majority showed relatively strong individual preferences. The subset of females that preferred the orange‐tailed over the wild‐type male in the first round of testing all maintained their preferences in the second round whether or not they had observed a model in association with the non‐preferred wild‐type male between tests. However, females that preferred the wild type over the orange male in the first round of testing copied the model's choice of the non‐preferred orange‐tailed male in their second round of preference testing. These results highlight the importance of recognizing the likelihood that only a subset of females will express a preference as it first emerges within a population. In such instances, the preference may not be detected at the population level—a point frequently overlooked in studies of mate choice. Additionally, these data highlight the importance of assessing the preferences of individual females and their capacity to drive evolutionary change within populations. Lastly, this study offers evidence of a possible mechanism by which a novel male trait might spread via mate choice copying by exploiting an emerging sensory bias within a subset of females in the population.

Environmentally Realistic Waterborne Atrazine Exposure Affects Behavior in Poecilia latipinna

“…III, the overall size of a single image of a displaying P. latipinna male was manipulated to generate 'small' (S), 'intermediate' (I), and 'large' (L) dummy stimuli measuring 40, 60, and 80 mm in total length, respectively (within the natural size range of males in this population; unpubl. data) in a similar fashion to those used in previous studies of this species [71,72] (Figure 1). Furthermore, the LD and HD concentrations of 1 and 15 ppb were identical to those used by Shenoy [2,19] in which negligible decreases were documented over 4-7 days without renewal in a closed system.…”

“…III, the overall size of a single image of a displaying P. latipinna male was manipulated to generate 'small' (S), 'intermediate' (I), and 'large' (L) dummy stimuli measuring 40, 60, and 80 mm in total length, respectively (within the natural size range of males in this population; unpubl. data) in a similar fashion to those used in previous studies of this species [71,72] (Figure 1).…”

“…Using the same fish image throughout negates this issue. Moreover, the methodology herein has been used in several previously published studies of mating preferences for visual traits in Poeciliid fishes including P. latipinna, e.g., [59,[71][72][73], X. helleri [62,74], X. variatus [64], and P. reticulata [63].…”

“…The testing environment for expts. I-III consisted of three 17.5-l aquaria (50 × 26 × 27 cm each) lined up end to end using an apparatus and protocol similar to the one used in previous poecilid mate preference experiments [59,[62][63][64][65][66][72][73][74]. Subjects were transferred from their isolation tanks into an aquarium that was divided into three zones by two black vertical lines drawn on the front wall: 30 × 26 × 13.5 cm 'neutral zone' flanked on each side by a 10 × 26 × 13.5 cm 'preference zone'.…”

2-D sex images elicit mate copying in fruit flies

“…However, little is known on the perception of flat images in non-human animals 1 , although several zoos empirically began using images to study mate choice in captive animals with the goal of stimulating reproduction by mimicking situations of mate choice 2,3 . More generally, the use of artificial visual stimuli in a wide variety of behavioural experiments is becoming a powerful methodology across all taxa involving clay models, robots, pictures, video playbacks, computer animated stimuli or even the use of virtual reality techniques [3][4][5][6][7][8][9][10][11][12][13][14] .…”