CK,
Concerning your next to last paragraph and the results of crosses that have been made thus far, I suggest ignoring the point about large and dwarf morphs. In other words, both reciprocal crosses (3 each) were made between boas of the Sierra Nevada and Northwestern subcades. All such crosses proved to be viable in that full term neonates were produced. Since these crosses occurred in recent years, insufficient time has elapsed in order to determine if the F-1 offspring are fertile.

However with respect to reproductive compatibility, it should be noted that the original cross in 1996 was between a Southern Clade male and Northern Clade female which produced 4 full term neonates. Of the two surviving male and female F-1 progeny, the F-1 female has been determined to be fertile. That a cross between specimens that have been isolated from between 4.4 to 12.3 million years (according to Javier's paper) can reproduce, produce full term neonates, and produce progeny that are themselves fertile does not lend support to any assumption that matings between members of the two subclades would result in infertile progeny.

Secondly, F-1 results between crosses of the two large morph populations would not likely shed any light on the factor(s) that produce the large morph condition. That is because regardless of the male parent, large morph females of the Northwestern subclade have produced only large morph progeny. Nothing of certainty can be mentioned about what large morph females of the Sierra Nevada subclade would produce but odds are that they too would produce only large morph progeny if mated to males the Northwestern subclade or males of the Southern Clade. One would have to take such crosses to either backcross or F-2 generations to potentially reveal differences that may occur.

Richard F. Hoyer

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