Type: report

Article abstract: Blainville’s horned lizard has numerous attributes that meet the criteria for an ecological indicator species. It is also listed as a ‘species of special concern’ by the California Department of Fish and Wildlife due to its shrinking distribution, over-collecting, and pressure from non-native species, and is a covered species under the San Diego MSCP. Of its life history attributes, dietary specialization on native harvester ants is a main driver of environmental sensitivity in P. blainvillii – where harvester ants decline or become extirpated, so do horned lizards. Members of the ant genera Pogonomyrmex, Veromessor, and Crematogaster are the main components of the P. blainvillii diet and are critical seed disperses for many of the region’s native plant species. These native harvester ants have been displaced by the invasive Argentine Ant Linepithema humile in large parts of southern California and elsewhere. Linepithema humile cannot substitute for native ants as a food source for P. blainvillii and hatchling P. blainvillii are incapable of persisting on diets of arthropods that are typical of invaded communities . The broad range of P. blainvillii across southern California (including numerous preserve systems) suggests that their population genetics might be useful in guiding the acquisition or restoration of linkage habitat, given that patterns of genetic admixture among different localities can signal where gene interchanges are currently being made, or where they occurred prior to major habitat conversion. To this end, we conducted a population genomic study on P. blainvillii across a large portion of the range to (1) generate baseline data on population genetic structure; (2) identify where current and/or historical genetic linkages occurred in southern California to guide acquisition, maintenance, or restoration efforts for linkage habitat; (3) to test whether certain populations have experienced declines or shifts in genetic diversity based on temporal sampling at certain localities; and (4) to compare population structuring with other available datasets from geographically overlapping taxa. An ancillary objective was to generate a genomic dataset for designing sequence capture probes that will provide an easy, costeffective assay for future genetic monitoring of this species.