Data from: Conservation genetics of the endangered Del Mar manzanita (Arctostaphylos glandulosa supsp. crassifolia) based on RAD sequencing data

Del Mar manzanita (Arctostaphylos glandulosa Eastw. subsp. crassifolia
(Jeps.) P.V. Wells) is a federally listed endangered shrub found in San
Diego County, California and Baja California, Mexico. This manzanita forms
part of the imperiled southern maritime chaparral of southwestern
California and adjacent Baja California, Mexico. Del Mar manzanita is
problematic to identify because of morphological intergradation with other
subspecies of A. glandulosa. Such intergradation could result from
biological phenomena, such as gene flow among subspecies. Alternatively,
it could be that the current circumscription of the Del Mar manzanita is
not correct, and that the morphological characters used to diagnose this
subspecies are inaccurate indicators of underlying genetics. This
situation leads to problems for conservation planning, where accurate
identification of individual plants is essential. Here, we used
high-throughput sequencing of restriction-site associated DNA markers
(RADseq) to develop single nucleotide polymorphism (SNP) data for a large
sample of putative Del Mar manzanita, and a small sample of closely
related subspecies of A. glandulosa. We analyzed genetic relationships
using a total of 65,964 SNPs, with the aim of testing whether
morphological traits used to identify Del Mar manzanita are an accurate
reflection of underlying genetic patterns. We conclude that vegetative
morphology is a poor predictor of genetic patterns, and that the current
morphology-based circumscription of Del Mar manzanita is probably in need
of some change. However, due to the limited sampling of A. glandulosa
subspecies in this study, it is not possible to determine the taxonomic
limits of Del Mar manzanita using our SNP data.