Diversification of the Genus Suaeda (Amaranthaceae): Use of Genome Skimming to Elevate Putative Species Radiation in Northwestern Mexico
Nearly 100 estuaries exist along the coast of Baja California and Sonora, Mexico, forming a series of unique wetland habitats isolated from each other by the surrounding arid landscape. The genus Suaeda Forssk. ex J.F. Gmel. (Amaranthaceae, formerly Chenopodiaceae) is common in these estuaries and has been hypothesized to be in the process of diversification. Nine putative new species of Suaeda were detected by Wayne Ferren during fieldwork in this region in the 1980s, but additional taxonomic study was needed before describing these as new to science. Nearly 350 specimens of both currently accepted and potentially new species of Suaeda were collected by Ferren from 1980-2000 and housed at the UCSB Natural History Museum at the Cheadle Center for Biodiversity and Ecological Restoration (CCBER) for curation and research. Here we aim to evaluate Ferren’s hypotheses using phylogenetic analysis of DNA sequence data. Genomic DNA was extracted from four exemplars of each putative species, along with four outgroup species. Genome skim libraries were constructed and sequenced on an illumina HiSeq 2500. The nuclear ribosomal cistron and chloroplast genome of each sample were assembled. We inferred evolutionary history with these resulting datasets and compared the results against Ferren’s taxonomic hypotheses to assess support for circumscription of new species. Beyond the implications for taxonomy, there is an urgent conservation need to ensure that biodiversity is adequately described, as these wetlands are threatened by development. Presented at the 2018 Southern California Botanists meeting.