Population genetics of the Four Corners potato (Solanum jamesii)

Premise: The domestication of wild plant species can begin with gathering
and transport of propagules by Indigenous peoples. The effect on genomic
composition, especially in clonal, self-incompatible perennials would be
instantaneous and drastic with respect to new, anthropogenic populations
subsequently established. Reductions in genetic diversity and mating
capability would be symptomatic and the presence of unique alleles and
genetic sequences would reveal the origins and ancestry of populations
associated with archaeological sites. The current distribution of the Four
Corners potato, Solanum jamesii Torr. in the Southwestern USA,
may thus reflect the early stages of a domestication process that began
with tuber transport. Methods: Herein genetic sequencing (GBS) data are
used to further examine the hypothesis of domestication in this culturally
significant species by sampling 25 archaeological and non-archaeological
populations. Key Results: Archaeological populations from Utah, Colorado,
and northern Arizona have lower levels of polymorphic loci, unique
alleles, and heterozygosity than non-archaeological populations from the
Mogollon Region of central Arizona and New Mexico. Principle components
analysis, Fst values, and structure analysis revealed that genetic
relationships among archaeological populations did not correspond to
geographic proximity. Populations in Escalante, Utah were related to those
on the Mogollon Rim (400 km south) and had multiple origins and
significant disjunctions with those in Bears Ears, Chaco Canyon, and Mesa
Verde.  Conclusions: Movement of tubers from the Mogollon Region
may have occurred many times and in multiple directions during the past,
resulting in the complex genetic patterns seen in populations from across
the Four Corners Region.