Predator experience overrides learned aversion to heterospecifics in stickleback species pairs

Abstract

Predation risk can alter female mating decisions because the costs of mate searching and selecting attractive mates increase when predators are present. In response to predators, females have been found to plastically adjust mate preference within species, but little is known about how predators alter sexual isolation and hybridization among species. We tested the effects of predator exposure on sexual isolation between benthic and limnetic threespine sticklebacks (Gasterosteus spp.). Female discrimination against heterospecific mates was measured before and after females experienced a simulated attack by a trout predator or a control exposure to a harmless object. In the absence of predators, females showed increased aversion to heterospecifics over time. We found that predator exposure made females less discriminating and precluded this learned aversion to heterospecifics. Benthic and limnetic males differ in coloration, and predator exposure also affected sexual isolation by weakening female preferences for colourful males. Predator effects on sexual selection were also tested but predators had few effects on female choosiness among conspecific mates. Our results suggest that predation risk may disrupt the cognitive processes associated with mate choice and lead to fluctuations in the strength of sexual isolation between species.

Predator‐induced maternal and paternal effects independently alter sexual selection

“…Mating preferences and decisions are also notoriously plastic; they respond strongly to changes in the chooser's internal condition and external ecological and social experience (reviewed in Jennions and Petrie 1997;Cotton et al 2006;Rosenthal 2017). Predation is one ubiquitous stressor that can change the course of sexual selection and population differentiation (Maan and Seehausen 2011;Kozak and Boughman 2015). Many animals experience predation risk during mating; under high predation risk, females often shift their mate preferences and choices to favor less conspicuous mates (Jennions and Petrie 1997;Lima 1998).…”

“…; Rosenthal ). Predation is one ubiquitous stressor that can change the course of sexual selection and population differentiation (Maan and Seehausen ; Kozak and Boughman ). Many animals experience predation risk during mating; under high predation risk, females often shift their mate preferences and choices to favor less conspicuous mates (Jennions and Petrie ; Lima ).…”

Predator-induced changes of male and female mating preferences: innate and learned components

“…We hypothesized that the predator-naïve cohort of test fish would change their mating preferences when facing the co-evolved predator (alluding to innate effects), whereas the predator-experienced cohort could respond more to the currently co-occurring predator if learning about predators also plays a role (Peterson et al. 2007; Kozak and Boughman 2015).…”

Synergistic selection between ecological niche and mate preference primes diversification

“…For example, niches that vary in the identity of predators and predation risk (due to different predation styles) can alter choosiness (Bierbach et al. ) and shift preference functions—females in a niche with more intense predation risk may prefer less conspicuous mates, which both shifts and narrows mate preference functions (Kozak and Boughman ).…”

“…Moreover, female mate choice can be altered in response to high predation to prefer less conspicuous males (Johnson and Basolo ; Bierbach et al. ; Bonachea and Ryan ,b; Kozak and Boughman ), which can shift the mate preference function and may also narrow it. High predation risk has repeatedly selected for less conspicuous individuals in both foraging and mating contexts (Nosil and Crespi ; Svanbäck and Eklöv ); thus, predation may have a synergistic effect on niche use and mate choice.…”