Figure 1.
Subspecies distribution and dorsal color patterns of the western shovel-nosed snake (Chionactis occipitalis) along with genetic sampling locations (black dots).
The presumed range of the morphological intergrade zone at the interface of C. o. annulata and C. o. klauberi is depicted by the dashed line.
Figure 2.
Phylogeny for the western shovel-nosed snake (Chionactis occipitalis) based on partitioned Bayesian analysis of mitochondrial DNA sequence data (16S rRNA and ND1 genes) and the geographic distribution of the major lineages (Mojave lineage in blue, Sonoran lineage in red, and Colorado lineage in green).
The geographic distribution of clades within each lineage are outlined with a dashed line, clade E (yellow clade and dots) was routinely placed as sister to the Sonoran lineage, but posterior probabilities supporting this relationship were weak (Pp < 0.50). Black circles at nodes represent Bayesian posterior probabilities of ≥ 0.95. See Figures S1-3 for more detail within each mtDNA lineage.
Table 1.
Divergence time estimates from BEAST analyses.
Table 2.
Summary of repeat motif, observed heterozygosity (HO), and expected heterozygosity (HE), total number of alleles (NA), and allelic richness (AR) for each microsatellite locus.
Figure 3.
Assignment probabilities based on the structure analysis (K = 3).
a) Each individual is represented by a single column with membership assignment probabilities for each of the three clusters (K) noted as the relative proportion of each color (blue, green, and red represent the Mojave, Colorado, and Sonoran clusters, respectively). The vertical black bars represent the a priori subspecies assignment for each individual that was used in the analysis.
Figure 4.
Range-wide geographic distribution of the three clusters inferred by structure (K = 3) overlaid on the subspecies distributions.
Circles on the map are colored proportional to their posterior probability assignment to each of the three clusters.
Figure 5.
Spatially-explicit estimate of population structure across Arizona based on the geneland analysis.
a) Map of Arizona and the geographic distribution of sampled individuals colored according to the probability of assignment within each cluster identified using geneland (green, orange, and red circles represent individuals assigned to Clusters A, B, and C, respectively). The shading indicates elevations below 300m (light grey), between 300 and 1000m (grey) and above 1000m (dark grey). b) Geneland probability contour maps for the three clusters across Arizona. The highest posterior probabilities are in white (p ≥ 0.9) and the lowest are in red (p ≤ 0.1) – contour lines within each map depict the spatial change in population assignment probability.
Table 3.
Genetic variability of microsatellite loci for each cluster identified using structure.
Table 4.
Pairwise Fst among clusters of Chionactis occipitalis identified by structure, all estimates were significant after Bonferroni correction.
Table 5.
Population migration rates (2NeM) estimated from IMa2.
Table 6.
Summary of each diagnostic characteristic for the Chionactis species complex based on the multi-locus dataset and Klauber [29]: values (n) below each species/subspecies name refer to the number of snakes for which both genetic & color pattern characters were collected, percentages represent the proportion of snakes that exhibited each phenotypic character.