Estimated population structure of Astyanax cave and surface population using STRUCTURE (Pritchard et al. 2000) for K = 2 and K = 5 population groups (Figure. 2). Each individual is represented by a thin vertical line, which is partitioned into K segments that represent its estimated population group membership fractions. Black lines separate individuals from geographical site locations (labeled below), which are as following: El Abra: O1 - O7; Chica (O8); Guatemala: N1 - N2; Micos: N3: Surface: S1 - S4. Figure 2B. Mean posterior probabilities of ten runs for each K, K = 1 to K = 12. Figure 2C. K = 5 had the highest ΔK vs. K peak height ).