Estimate of demographic history
In the analyses of demographic change, the stairway plots of the eight populations show similar patterns, with population size declining dramatically from around 100 thousand to a few thousands individuals within the last 30 thousand years (Figure 6 ). According to the stairway plots, the sample sites 1 and 3 (N. riversi ) have similar patterns of population decline starting around 25 thousand years ago, but the ancestral population was larger in site 3, a site located in the contact zone of the Merced and San Joaquin drainage systems (Figure 6A & B ). The sites 9, 10, and 12 represent intermediate morphotypes located within San Joaquin drainage, and they share similar patterns of decline starting around 10 thousand years ago (Figure 6C, D, &E ). The three sites of N. ingens , from the Kings (site 17), Kaweah (site 24), and Kern (site 27), shows declines ranging from 20 thousand to two thousand years ago (Figure 6F, G, &H ).