Figure 3.

Different clades were diversified and highly expressed in Crotalus adamanteus and C. horridus for the phospholipase A₂ (PLA2) gene family. The bars adjacent to gene names give expression levels relative to the most highly expressed family member by species. A completely colored bar indicates the highest expression for the species. Clades comprising sequences from a single species either represent gene-family expansion for that species or gene-family contraction for the other. The four-gene clade including Chorr PLA2-1a and the five-gene clade including Cadam PLA2-1a are clear examples of this phenomenon. Duplication and gene-loss events were inferred by means of a duplication-loss parsimony model. We used a homologous nontoxin-PLA2 sequence from the european rabbit (Oryctolagus cuniculus) as an outgroup to root the phylogeny. Bayesian posterior probabilities are shown for clades for which the values exceeded 50%. Numbers within circles indicate that more than one duplication event was inferred for that node.