Population and migration models
Model 4 (Figure 2) was the best fit model as determined by Bayes Factors in the MIGRATE-N analysis (Table S5). This result was consistent across both runs of the program with alternative phasing. Model 4 divided the population into three groups: high elevation MT, low elevation MT, and MK, with high rates of bidirectional migration between all pairs. The next best model was model 5, which divides the population into high elevation MT and low elevation MT + MK with bidirectional migration (Figure 2). Across models, the mean migration rate from high elevation MT to MK was greater than from MK to MT (1.3–19×, Table S6).
The results from NeEstimator suggest a larger effective population size on MT (< 2000 masl + ≥ 2000 masl) than MK despite the smaller available habitat on MT (250 vs. 125, respectively) (Table 2 and Supplemental Information).