Therefore, although the population from Nopalillo may be basal and therefore viviparity may have appeared once in the node leading to the rest of the bicanthalis clade, the most parsimonious topology indicates a reversal from viviparity to oviparity at this locality [ILLUSTRATION FOR FIGURE 5 OMITTED].
1996) based on phylogenetic analysis suggest that reversal from viviparity to oviparity is possible among squamates.
The transition from oviparity to viviparity must at some point involve polymorphism for the length of egg retention, and eventually for parity mode, and that stage is what may be evident in the population from Las Vigas, Veracruz (locality 6 in [ILLUSTRATION FOR FIGURE 2 OMITTED]).
This lack of correlation may be an artifact of either: (1) sampling only the two extremes (oviparity vs.
As at the family level, oviparity and viviparity represent in all cases except one the plesiomorphic characters and egg guarding the derived character (in 70.5% of all reconstructions, oviparity is the ancestral character; in 29.49%, it is viviparity; and in only 0.01%, it is egg guarding).
As in the cases of families and genera, oviparity and viviparity represent in all cases the plesiomorphic character states and egg guarding the derived character state (in 60% of all reconstructions, oviparity is the ancestral character; and in 40%, it is viviparity).
In particular, there is a strong deficit in the transition between egg guarding to viviparity compared with viviparity to oviparity with egg guarding ([Mathematical Expression Omitted]; P [less than] 0.001).
All reconstructions with MacClade of the life-history character show that oviparity is the ancestral character in 73.6%, viviparity in 26.397%, and egg guarding in 0.003%.