Fig. 4: Hypotheses of the origin of Lambda and its initial expansion in South America.

Maximum clade credibility tree from trees of the posterior distribution where Peru (a) or Argentina (b) was estimated as the root. Labels indicated the high posterior density 95% of the dates of the first node of each country that indicate the estimation of the dates of origin of Lambda in each of these countries. Nodes are colored according to the country (Peru = Red, Argentina = Blue, Chile = Green). Arrows indicate from where to where the first transitions to each country occurred. At the left as inset, a graphic map summarizing the transitions of Lambda between countries is shown. At the right, distribution of the date of the node representing the first transition between Peru to Chile (green), Peru to Argentina (blue) or Argentina to Peru (red) is displayed. Vertical lines indicate 95% high posterior density. The number of trees analysed (n) from the posterior distributions was 636 when Peru was the root, and 341 when Argentina was the root.