Of Mojave milkweed and mirrors: The population genomic structure of a species impacted by solar energy development

A rapid renewable energy transition has facilitated the development of
large, ground‐mounted solar energy facilities worldwide. Deserts, and
other sensitive aridland ecosystems, are the second most common land‐cover
type for solar energy development globally. Thus, it is necessary to
understand existing diversity within environmentally sensitive desert
plant populations to understand spatiotemporal effects of solar energy
siting and design. Overall, few population genomic studies of desert
plants exist, and much of their biology is unknown. To help fill this
knowledge gap, we sampled Mojave milkweed (Asclepias nyctaginifolia) in
and around the Ivanpah Solar Electric Generating Station (ISEGS) in the
Mojave Desert of California to understand the species' population
structure, standing genetic variation, and how that intersects with solar
development. We performed Restriction‐site Associated Sequencing (RADseq)
and discovered 9942 single nucleotide polymorphisms (SNPs). Using these
data, we found clear population structure over small spatial scales,
suggesting each site sampled comprised a genetically distinct population
of Mojave milkweed. While mowing, in lieu of blading, the vegetation
across the solar energy facility's footprint prevented the immediate
loss of the ISEGS Mojave milkweed population, we show that the effects of
land‐cover change, especially those impacting desert washes, may impact
long‐term genetic diversity and persistence. Potential implications of
this include a risk of overall loss of genetic diversity, or even hastened
extirpation. These findings highlight the need to consider the genetic
diversity of impacted species when predicting the impact and necessary
conservation measures of large‐scale land‐cover changes on species with
small population sizes.