>>Regarding this "catastrophic event"? I have read some of Robles-Rodrigues work and have not found any definitive answer, and I've also not researched futher into it. Too much of the past distracts from "the now" I always say, but it is important to know IMO. Good stuff though.>>

The past catastrophic event was probably the expansion of the Mojave Desert. IIRC, the Mojave Desert once extended into Oregon and possibly beyond, according to some geology articles that I came across. There is evidence that the distribution of Ensatina was also affected by this catastrophe. Ensatina eschscholtzii croceator, for example, is probably most closely related to E. e. klauberi, but the blotched forms of Ensatina are absent from the San Gabriel Mountains. Instead, the Monterey Salamander (E. e. eschscholtzii) is found in the San Gabriels. Quite obviously this past catastrophe must have wiped most of the mountains of Southern California (including the San Gabriels, Santa Monicas and Santa Ana Mts.) clean of the blotched forms of Ensatina, enabling the Monterey salamander to colonize this area at a later date. Just like L. zonata, Ensatina may have taken refuge in the mountains of northern Baja California and then expanded northward back into the mountains of San Diego, just as L. z. agalma did before evolving into L. z. pulchra.

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