Table S1 Measures of microsatellite diversity and the results of tests for linkage disequilibrium and conformation to HWE for N. harteri collected from the Clear Fork of the Brazos (CF) and Brazos River (BZ) within the Brazos River Basin (BRB), and the Colorado River (CO) and Concho River (CH) within the Colorado River Basin (CRB)

Group / Locus / Aa / Nb / HOc / HEd / LDe / BRDf / CFf / BZf
N.h.h / Ts3 / 1 / 32 / 0.00 / 0.00
Nsm3 / 7 / 31 / 0.42 / 0.73 / * / *
3Ts / 8 / 32 / 0.41 / 0.81 / *
Nsm4 / 2 / 32 / 0.06 / 0.06
Ebom1 / 4 / 32 / 0.84 / 0.58 / * / *
Mean / 4.40 / 32 / 0.35 / 0.43
CRDf / COuf,g / COdf,h / CHf
N.h.p / Ts3 / 2 / 64 / 0.34 / 0.43
Nsm3 / 8 / 64 / 0.61 / 0.77 / Ebou1 / *
3Ts / 8 / 64 / 0.61 / 0.81 / *
Nsm4 / 1 / 64 / 0.00 / 0.00
Ebom1 / 2 / 64 / 0.19 / 0.50 / *
Mean / 4.20 / 64 / 0.35 / 0.50

a The number of alleles per locus

b Number of individuals sampled

c Observed heterozygosity

d Expected heterozygosity

e Pairs of loci in linkage disequilibrium

f Asterisks represent significant deviations from HWE

g upper Colorado River

h lower Colorado River


Table S2 Measures of microsatellite diversity and the results of tests for linkage disequilibrium and conformation to HWE for N. e. transversa

HWE f
Locus / Aa / Nb / HOc / HEd / LDe / BRD / CRD
Ts3 / 11 / 34 / 0.71 / 0.86 / 3Ts / * / *
Nsm3 / 12 / 34 / 0.77 / 0.86 / *
3Ts / 19 / 34 / 0.77 / 0.93 / * / *
Nsm4 / 6 / 34 / 0.15 / 0.64 / * / * / *
Ebom1 / 10 / 34 / 0.50 / 0.82 / * / *
Mean / 11.60 / 34 / 0.58 / 0.82

a The number of alleles per locus

b Number of individuals sampled

c Observed heterozygosity

d Expected heterozygosity

e Pairs of loci in linkage disequilibrium

f Asterisks represent significant deviations from HWE

Table S3 Pairwise measures of FST based on five microsatellite loci (lower diagonal) and cyt-b mitochondrial haplotypes (upper diagonal) for Nerodia erythrogaster transversa collected from the Clear Fork of the Brazos (CF), Colorado River (CO), and the Concho River (CH)

CF / CO / CH
CF / - / 0.25 / 0.51
CO / 0.05 / - / 0.29
CH / 0.06 / 0.02 / -

P < 0.05 in bold

Fig. S1 Relative frequencies of cyt-b haplotypes in N. e. transversa collected from the Clear Fork of the Brazos (CF), Colorado River (CO), and the Concho River (CH)

Fig. S2 Network of N. e. transversa cyt-b haplotypes from the Colorado and Brazos river basins. Dashes between nodes represent the number of base changes. Sample sizes are given in parenthesis, and the proportion of individuals carrying a particular haplotype is represented by the area within each node. Sequences were accessioned into GenBank (JQ754309-JQ754320)

Fig. S3 Mean L(K) for each K and standard deviations from STRUCTURE analyses for all N. e. transversa pooled together. Results indicate no population structure in the sample

Fig. S4 Calculations of DK from STRUCTURE results when all N. e. transversa were pooled together. Low values indicate no population structure in the sample