“…This region coincides geographically with an area in which a relatively large, localized genetic discontinuity is also found between Ensatina eschscholtzii oregonensis (Oregon ensatina salamander) and E. e. platensis (Sierra Nevada ensatina salamander; Jackman and Wake, 1994). As suggested for E. eschscholtzii, much local extinction and recolonization has probably occurred in the Lassen region due to at least two main factors: extensive volcanism (Lassen Peak has been volcanically active in the last 100 years; Clynne, 1999;Norris et al, 1997) and the fact that this upland area was subjected to glaciation during the Pleistocene, when ice sheets extended as low as about 1500 m and the regional snow line (the lower limit of perennial snow) was about 2000 m lower than at present (about 4200 m; Kane, 1982;Rogers et al, 1991). Much of the usable habitat for C. bottae would have been eliminated during these periods, which would have prevented contact between rubber boas dispersing from the south and those migrating from the east, north, or west.…”