Table 1.

Overview of gene categories

Category	G	Cr	O1	O2	Suggested content of imports
A	+	-	-	-	Recent imports or loss of imports from B
B	+	+	-	-	Less recent imports
C	+	-	+	+	Loss of genes in Cr, or pervasive imports
D	+	+	+	+	Only highly pervasive imports expected

G, genome under consideration; Cr, paired close relative; O1, first outgroup organism; O2, second outgroup organism. +, Present; -, absent.