Abstract The genetic basis of traits shapes and constrains how adaptation proceeds in nature; rapid adaptation can proceed using stores of polygenic standing genetic variation or hard selective sweeps, and increasing polygenicity fuels genetic redundancy, reducing gene re-use (genetic convergence). Guppy life history traits evolve rapidly and convergently among natural high- and low-predation environments in northern Trinidad. This system has been studied extensively at the phenotypic level, but little is known about the underlying genetic architecture. Here, we use four independent F2 QTL crosses to examine the genetic basis of seven (five female, two male) guppy life history phenotypes and discuss how these genetic architectures may facilitate or constrain rapid adaptation and convergence. We use RAD-sequencing data (16,539 SNPs) from 370 male and 267 female F2 individuals. We perform linkage mapping, estimates of genome-wide and per-chromosome heritability (multi-locus associations), and QTL mapping (single-locus associations). Our results are consistent with architectures of many loci of small-effect for male age and size at maturity and female interbrood period. Male trait associations are clustered on specific chromosomes, but female interbrood period exhibits a weak genome-wide signal suggesting a potentially highly polygenic component. Offspring weight and female size at maturity are also associated with a single significant QTL each. These results suggest rapid, repeatable phenotypic evolution of guppies may be facilitated by polygenic trait architectures, but subsequent genetic redundancy may limit gene re-use across populations, in agreement with an absence of strong signatures of genetic convergence from recent analyses of wild guppies.
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Consistent female preference for rare and unfamiliar male color patterns in wild guppy populations
How genetic variation is maintained in ecologically important traits is a central question in evolutionary biology. Male Trinidadian guppies, Poecilia reticulata, exhibit high genetic diversity in color patterns within populations, and field and laboratory studies implicate negative frequency-dependent selection in maintaining this variation. However, behavioral and ecological processes that mediate this selection in natural populations are poorly understood. We evaluated female mate preference in 11 natural guppy populations, including paired populations from high- and low-predation habitats, to determine if this behavior is responsible for negative frequency-dependent selection and to evaluate its prevalence in nature. Females directed significantly more attention to males with rare and unfamiliar color patterns than to males with common patterns. Female attention also increased with the area of male orange coloration, but this preference was independent of the preference for rare and unfamiliar patterns. We also found an overall effect of predation regime; females from high-predation populations directed more attention toward males than those from low-predation populations. Again, however, the habitat-linked preference was statistically independent from the preference for rare and unfamiliar patterns. Because previous research indicates that female attention to males predicts male mating success, we conclude that the prevalence of female preference for males with rare and unfamiliar color patterns across many natural populations supports the hypothesis that female preference is an important process underlying the maintenance of high genetic variation in guppy color patterns.
more » « less- Award ID(s):
- 1740466
- NSF-PAR ID:
- 10123589
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Behavioral Ecology
- Volume:
- 30
- Issue:
- 6
- ISSN:
- 1045-2249
- Page Range / eLocation ID:
- p. 1672-1681
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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