Expression of additive genetic variance for fitness in a population of partridge pea in two field sites

Abstract

Despite the importance of adaptation in shaping biological diversity over many generations, little is known about populations’ capacities to adapt at any particular time. Theory predicts that a population's rate of ongoing adaptation is the ratio of its additive genetic variance for fitness, VAfalse(Wfalse), to its mean absolute fitness, W¯. We conducted a transplant study to quantify W¯ and standing VAfalse(Wfalse) for a population of the annual legume Chamaecrista fasciculata in one field site from which we initially sampled it and another site where it does not currently occur naturally. We also examined genotype‐by‐environment interactions, G × E, as well as its components, differences between sites in VAfalse(Wfalse) and in rank of breeding values for fitness. The mean fitness indicated population persistence in both sites, and there was substantial VAfalse(Wfalse) for ongoing adaptation at both sites. Statistically significant G × E indicated that the adaptive process would differ between sites. We found a positive correlation between fitness of genotypes in the “home” and “away” environments, and G × E was more pronounced as the life‐cycle proceeds. This study exemplifies an approach to assessing whether there is sufficient VAfalse(Wfalse) to support evolutionary rescue in populations that are declining.

Additive genetic variance for lifetime fitness and the capacity for adaptation in an annual plant

“…Our previous work focusing on the Grey Cloud population revealed positive correlations of breeding values between fitness components and also two environments (Sheth et al. ). This result suggests that trade‐offs (i.e., negative genetic correlations) do not account for the maintenance of observed levels of V A (W).…”

“…We then constructed models that explicitly equated the variance due to sires with that for dams (i.e., modeling the equal nuclear transmission of each parent to their offspring) and estimated a single variance component for their effects (hereafter parental effects), with sire effects being (Sheth et al. ). From separate analyses, also including blocks as fixed effects, we estimated .…”

Climate change shifts natural selection and the adaptive potential of the perennial forbBoechera strictain the Rocky Mountains

“…For example, Sheth et al. () found substantial genetic variation in fitness in a C. fasciculata population planted both at a novel site and at a site where it naturally occurs. However, only a handful of studies have explicitly examined the relationship between genetic variation in a trait and the strength of its association with fitness in the wild (Teplitsky et al.…”

“…We did not include garden or experimental environment as random effects because our models consider all gardens and experimental environments of interest, and because it is advisable to reduce the number of random effects in generalized linear‐mixed models when possible (Sheth et al. ).…”

“…Assessing the adaptive potential of populations under climate change remains challenging (Shaw and Etterson ; Sheth et al. ; Torres‐Martínez et al. ).…”