An Adaptive Threshold in Mammalian Neocortical Evolution
Figure 2
Clustering of GI values based on life-history association analysis (A) and minimum-energy distance (B).
(A) Stochastic mapping of physiological and life-history traits with GI values for the 102 mammalian species listed in Table S1. GI values were separated into four groups based on clustering. Thirty-seven traits (bold letters), each comprising two to eight character states (regular letters), were analyzed (see Table S2 for a complete list), and the states showing a significant positive (P, green) or negative (N, red) association with a group of GI values are shown. Traits are listed according to their positive associations with each GI group moving from least to most gyrencephalic. Note the major overlap between the two low-GI groups (10/27) and between the two high-GI groups (9/24), whereas only 3/48 character states are shared between GI groups <1.5 and >1.5. (B) Hierarchical clustering based on minimum-energy distance of the GI values for 101 mammalian species (see Table S1, with Cynocephalus volans being omitted from this analysis). Note that the greatest clustering height is between species with GI values ≤1.5 and >1.5. Species of the various taxonomic groups are colored according to Figure 1.