The complexities of female mate choice and male polymorphisms: Elucidating the role of genetics, age, and mate-choice copying

Abstract

Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across populations, and thus the action and outcome of sexual selection. This study explores patterns of inheritance, diet, age, and mate-choice copying on the expression of male sexual signals and associated female mate choice in a phenotypically diverse group of Schizocosa wolf spiders. Focal spiders exhibit one of two male phenotypes: ‘ornamented’ males possess large black brushes on their forelegs, and ‘non-ornamented’ males possess no brushes. Using a quantitative genetics breeding design in a mixed population of ornamented/non-ornamented males, we found a strong genetic basis to male phenotype and female choice. We also found that some ornamented males produced some sons with large brushes and others with barely visible brushes. Results of diet manipulations and behavioral mating trials showed no influence of diet on male phenotype or female mate choice. Age post maturation, however, influenced mate choice, with younger females being more likely to mate with ornamented males. A mate-choice copying experiment found that, following observations of another female’s mate choice/copulation, virgin mature females tended to match the mate choice (ornamented vs. non-ornamented males) of the females they observed. Finally, analyses of genetic variation across phenotypically pure (only one male phenotype present) vs. mixed (both phenotypes present) populations revealed genetic distinction between phenotypes in phenotypically-pure populations, but no distinctionin phenotypically-mixed populations. The difference in patterns of genetic differentiation and mating across geographic locations suggests a complex network of factors contributing to the outcome of sexual selection.

Mechanisms of Social Influence: A Meta-Analysis of the Effects of Social Information on Female Mate Choice Decisions

“…However, low taxonomic representation of some clades reflects the lingering lack of tests in those taxa. While it makes sense that highly social animals would be more likely to transfer information among conspecifics during matechoice, studies robustly indicating the occurrence of mate-choice copying in Drosophila melanogaster and in wolf spiders indicate that complex sociality is not required for mate-choice copying to occur, and that a phylogenetic interpretation of the pattern of mate-choice copying across taxa suggests that it occurred in the common ancestor of all Nephrozoa (Fowler-Finn et al, 2015;Danchin et al, 2018;Monier et al, 2018;Nöbel et al, 2018). We suggest that mate-choice copying is not an isolated and discreetly evolved trait within social animals, but rather one of many manifestations of an underlying evolved cognitive ability to observe and copy the choices of others.…”

“…In taxonomically diverse animals, and in a variety of situations other than mate choice, social information has a greater influence when observers are young or otherwise inexperienced, for example when they encounter new environments or when a preferred choice is unavailable (Galef and Giraldeau, 2001;Valone and Templeton, 2002; but see Loukola et al, 2012). In mate-choice copying, this suggests that young or sexually inexperienced females should be more likely to copy the mate choices of others, as has been reported in guppies and wolf spiders (Dugatkin and Godin, 1993;Fowler-Finn et al, 2015).…”

“…Regular reviews in the subsequent decades indicate the sustained interest in mate-choice copying and its implications for sexual selection (Gibson and Höglund, 1992;Nordell and Valone, 1998;Vakirtzis, 2011;Witte et al, 2015;Varela et al, 2018). Mate-choice copying occurs in a wide array of organisms, from humans (Waynforth, 2007;Gouda-Vossos et al, 2018;Homo sapiens) to Schizocosa wolf spiders (Fowler-Finn et al, 2015), including in animals that lack complex cognitive abilities or social systems (Danchin et al, 2018). Given the apparent prevalence and importance of matechoice copying, we aimed to assess the magnitude of its effects as well as the factors that influence this phenomenon.…”

The Role of Learning on Insect and Spider Sexual Behaviors, Sexual Trait Evolution, and Speciation

“…The acquisition of a preference for visual traits has also been reported in fruit flies [eye color, (Verzijden et al, 2015)], butterflies [hindwing ornamentation number, (Westerman et al, 2014)], or crickets [size, (Bateman et al, 2001)] (Figure 2). Recent studies on matechoice copying showed that virgin individuals tend to prefer male phenotypes with similar color type and ornamentation as the mate choice of another conspecific, e.g., in spiders, (Fowler-Finn et al, 2015) and fruit flies, (Mery et al, 2009;Nöbel et al, 2018a). These cases illustrate that insects can generalize socially learned public information for choosing a mate.…”

“…Fowler -Finn et al, 2015 Wolf spider Hogna helluo Exposure Full phenotype, visual, and olfactory. Exposure without mating: adult females paired with males, no mating allowed, but visual and olfactory cues available; or females kept individually without exposure.…”