GMYC model for the mtDNA data for Clade I. Phylogenetic tree (left), single (S) threshold likelihood solutions to the GMYC model (center), and lineage-through-time plot (right). Log number of lineages (N) vs. time (mya) graph from GMYC analysis based on a Bayesian tree. The threshold between intra- vs. inter-species variation is indicated by a vertical red line. The single threshold GMYC result is indicated for a single line (4.13 mya: red bars). The multiple-threshold GMYC result (lower plot) reflects the results of four thresholds (3.71 mya: red bars, 2.56 mya: green bars, 1.48 mya: blue bars, and 0.68 mya: purple bars).