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 ).