Homogenization of Populations in the Wildflower, Texas Bluebonnet (Lupinus texensis)

Abstract

Wildflower seeds are routinely spread along highways and thoroughfares throughout North America as part of federal beautification policy, but the genetic effect of the introduction of these cultivated populations on wild populations of the same species is unknown. Interbreeding may occur between these seeded and wild populations, resulting in several possible outcomes. Here we sample 187 individuals in 12 matched pairs of neighboring wild and seeded populations of the Texas bluebonnet (Lupinus texensis), a species popular in commercially available wildflower seed mixes used by both the Texas Department of Transportation and the public. We use genotyping by sequencing to identify 11741 genome-wide single nucleotide polymorphisms, as well as a smaller number of SNPs from the chloroplast genome, to analyze population structure and genetic diversity within and between the populations. We find a striking lack of population structure both between wild and seeded populations and amongst wild populations. STRUCTURE analyses indicate that all populations are apparently panmictic. This pattern may be explained by extensive swamping of wild populations by seeded germplasm and increased dispersal of semi-domesticated seed across this species' core native range by humans. We discuss the possible negative and positive ramifications of homogenization on the evolutionary future of this popular wildflower species.

Pleistocene glacial cycles drive isolation, gene flow and speciation in the high‐elevation Andes

“…Although there are no data on seed dispersal and few observations of pollinators for Andean Lupinus, the dispersal mechanism in almost all species in the genus is ballistic dispersalthe seed pods dry and explosively dehisce, ejecting the seeds at most a few metres away from the parent plants (e.g. 0-4 m for the North American species L. texensis; Turner et al, 2017). Furthermore, the seeds of wild Andean lupins are relatively large and smooth and not easily transported by wind, while pollination is typically dependent on bees (Langridge & Goodman, 1977), which are also infrequent in the high-elevation Andes.…”

Genome-wide sequence-based genotyping supports a nonhybrid origin ofCastanea alabamensis

“…The advent of affordable genome-wide sequence-based genotyping methods has recently allowed new insights into questions of hybridization and admixture in plants (Escudero et al, 2014; Eaton et al, 2015; Baute et al, 2016; Owens et al, 2016; Leroy et al, 2017; McVay et al, 2017; Zhao et al, 2018; Turner et al, 2018). The availability of large numbers of markers distributed across the genome has allowed researchers to address questions that were previously intractable with less comprehensive datasets.…”

Trait evolution during a rapid global weed invasion despite little genetic differentiation

“…Compared to other short‐lived outcrossing species, these F S T statistics fall towards the lower end of measures of highly homogenized populations of Lupinus texensis ( F ST from 0.0007 to 0.018) versus populations with an intact native structure such as Nigella degenii ( F ST from 0.03 to 0.07) and Clarkia xantiana ssp . xantiana ( F ST from 0.048 to 0.171) (reviewed in Turner et al, 2018). STRUCTURE and DAPC results at neutral SNPs showed limited genetic substructure in the introduced range, consistent with recent colonization and in line with previous results (Barker et al, 2017; Eriksen et al, 2014).…”