Swordtail Fry Attend to Chemical and Visual Cues in Detecting Predators and Conspecifics

Abstract

Predation pressure and energy requirements present particularly salient opposing selective pressures on young fish. Thus, fry are expected to possess sophisticated means of detecting predators and resources. Here we tested the hypotheses that fry of the swordtail fish Xiphophorus birchmanni use chemical and visual cues in detection of predators and conspecifics. To test these hypotheses we presented young (<7 day-old) fry with combinations of visual and chemical stimuli from adult conspecifics and predators. We found that exposure to predator odors resulted in shoal tightening similar to that observed when fry were presented with visual cues alone. In trials with conspecific stimuli, fry were particularly attracted to adult conspecifics when presented simultaneous visual and chemical stimuli compared to the visual stimulus alone. These results show that fry attend to the odors of adult conspecifics, whose presence in a particular area may signal the location of resources as well as an absence of predators. This is one of the first studies to show that such young fish use chemical and visual cues in predator detection and in interactions with conspecifics. Previous research in X. birchmanni has shown that anthropogenic alteration of the chemical environment disrupts intraspecific chemical communication among adults; we suggest that because fry use the same chemosensory pathways to detect predators and conspecifics, alteration of the chemical environment may critically disrupt predator and resource detection.

An Indirect Cue of Predation Risk Counteracts Female Preference for Conspecifics in a Naturally Hybridizing Fish Xiphophorus birchmanni

“…Cichlid fishes co-occur with all northerm swordtail species and are likely important predators [30], [48], as are birds (GGR, unpub. dat.).…”

“…Mate sampling under threat of predation likely occurs In wild Xiphophorus [30] , [47] . Cichlid fishes co-occur with all northerm swordtail species and are likely important predators [30] , [48] , as are birds (GGR, unpub. dat.).…”

“…First generation hybrids occur at very low frequencies, with a greater preponderance of backcross individuals and later generation hybrids [28] . The two species inhabit shallow rocky streams subject to seasonal flooding and drought [29] , and likely experience considerable variation in predation pressure, to which swordtails attend [30] , [31] . Males of each species differ morphologically in several ways [27] , [29] .…”

Divergent neurogenomic responses shape social learning of both personality and mate preference

“…Xiphophorus birchmanni are bolder than X. malinche and show repeatable within-individual covariance among measures of boldness (Boulton et al, 2014;Johnson et al, 2015). In addition to sexual cues, swordtails attend to social information outside the context of mating (Wong and Rosenthal, 2005;Coleman and Rosenthal, 2006), suggesting that boldness might also be sensitive to social experience. In the present study, we show that social experience simultaneously drives intraspecific differences in both learned personality and mating preferences, and that the neural mechanisms driving the development of these behaviors are themselves dependent on social upbringing.…”

Learning performance is influenced by the social environment in cichlid fishes.

“…In Experiments 3 and 4, we tested individuals’ abilities to learn about shelter. We expected shelter to be a particularly ecologically salient reward for both species because they both use shelters for predator avoidance and breeding under natural social conditions ( Brown & Chivers, 2005 ; Coleman & Rosenthal, 2006 ; O’Connor, Reddon, Odetunde, Jindal, & Balshine, 2015 ). Overall, we tested two competing hypotheses.…”