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]).
As a result, our single category of oviparity may be too simplistic, and may hide significant correlations.
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.
All reconstructions with MacClade of the life-history character show that oviparity is the ancestral character in 73.
O, oviparity without egg guarding; G, oviparity with egg guarding; and V, viviparity.