American Society of Naturalists

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“Mating preference for novel phenotypes can be explained by general neophilia in female guppies”

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Mitchel J. Daniel, Laura Koffinas, and Kimberly A. Hughes (Oct 2020)

Mating preference for novel phenotypes can be explained by general neophilia in female guppies

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Male Trinidadian guppies (<i>Poecilia reticulata</i>). (Credit: Mitchel J. Daniel)
Male Trinidadian guppies (Poecilia reticulata). (Credit: Mitchel J. Daniel)

Why is it good to be different? In many species, individuals prefer mates that have novel or unusual features, such as unusual coloration. This preference has important evolutionary implications; if individuals with novel or unusual features have a mating advantage, this can prevent the loss of rare traits, thereby maintaining genetic diversity. However, the reason for this attraction to novelty is unclear.

A new study by Mitchel Daniel, Laura Koffinas, and Kimberly Hughes at Florida State University shows that for female Trinidadian guppies, preference for mates with unusual color patterns is linked to preference for novelty in other parts of their lives. The authors put female guppies through an Olympiad of behavioral tests to determine whether they preferred novel features over familiar ones in a variety of different contexts. They find that, on average, female guppies prefer to mate with males that have novel color patterns over males that have familiar color patterns, prefer to eat novel foods over familiar foods, and prefer to explore novel environments over spending time in familiar locations. (Females show the reverse preference, however, when it comes to associating with other females, preferring familiar females to unfamiliar ones). The researchers also find evidence of consistent behavioral differences: the females who most prefer mates with unusual color patterns are also the ones who most prefer novel foods, environments, and even females.

Females that prefer novel foods and environments may have an evolutionary advantage because they are more likely to discover new resources, habitats. If natural selection favored novelty-seeking behavioral type for these reasons, preference for mates with unusual traits might have become more common as an evolutionary side-effect. In this way, preference for mates with unusual color patterns could be a by-product of natural selection favoring novelty-seeking for reasons unrelated to mating.


Abstract

Understanding how genetic variation is maintained in ecologically-important traits is a fundamental question in evolutionary biology. Male Trinidadian guppies (Poecilia reticulata) exhibit extreme genetic diversity in color patterns within populations, which is believed to be promoted by a female mating preference for rare or novel patterns. However, the origins of this preference remain unclear. Here, we test the hypothesis that mating preference for novel phenotypes is a by-product of general neophilia that evolved in response to selection in non-mating contexts. We measured among-female variation in preference for eight different, novel stimuli that spanned four ecological contexts: mate choice, exploration, foraging, and social (but non-sexual) interactions. Females exhibited preference for novelty in 6 out of 8 tests. Individual variation in preference for novelty was positively correlated among all 8 types of stimuli. Furthermore, factor analysis revealed a single axis of general neophilia that accounts for 61% of individual variation in preference for novel color patterns. The single-factor structure of neophilia suggests that interest in novelty is governed primarily by shared processes that transcend context. Because neophilia likely has a sizable heritable component, our results provide evidence that mating preference for novel phenotypes may be a non-adaptive by-product of natural selection on neophilia.