Domestication During Restoration: Unintentional Selection During Eight Generations of Wild Seed Propagation Reduces Herkogamy, Dichogamy and Heterozygosity in Clarkia pulchella.

Abstract

Seed production on native seed farms has increased to meet the rising demand for plant material for restoration. Although these propagation efforts are necessary for restoration, cultivating wild populations may also result in unintentional selection and elicit evolutionary changes that mimic crop domestication, essentially turning these efforts into artificial domestication experiments. Here, we investigated whether phenotypic and genomic changes associated with domestication occurred in the wildflower Clarkia pulchella Pursh (Onagraceae) by comparing the wild source populations to the farmed population after eight generations of cultivation. At the phenotypic level, the farmed population shifted towards a floral morphology associated with self-pollination, with a significant decrease in both dichogamy and herkogamy. At the genomic level, > 6500 SNPs revealed that mean expected heterozygosity of the farmed population was significantly lower than the wild populations, despite the fact that the farmed population originated from a pool of multiple wild populations. Both the shift towards a selfing phenotype and the loss of diversity are expected consequences of domestication, although the phenotypic shifts in particular occurred much more rapidly than has been observed for other domestication traits. We discuss these results in the context of plant domestication and the implications for retaining the genetic integrity of wild populations during the process of seed production for restoration.