Figure 6
Derivation of silk gland specific expression. Classification of branches in phylogenies inferred for 605 BlastClust clusters containing representatives from all three cobweb weaving species and at least one transcript with expression levels 2-fold higher in silk glands than non-silk glands (see Fig. 7 for exemplar trees and Supplementary File 5 for all phylogenies). Each branch was classified according to whether or not there was a change in expression state between the ancestral node and the descendant. Maximum likelihood ancestral FPKM was determined for each gland type independently. If the mean FPKM was more than 2-fold greater in silk glands than non-silk glands, the node was assigned to the silk gland type with the majority of the expression, or to “multiple” glands if no majority (Supplementary File 4). Branches deriving from duplication and speciation nodes are shown seperately (n = number of nodes). Asterisks (*) denote significant differences in changing expression state between duplication and speciation nodes with Fisher’s exact test after Bonferroni multiple test correction. Fisher’s exact test is appropriate here due to the imbalance in number of speciation and duplication nodes and limited instances of changing expression states for some tissues.
