Phylogenetic distributions of host-plant taxa arising from different speciation modes in insects. (a) Distribution of host-plant taxa on the phylogeny of a hypothetical insect group in which speciation is mainly allopatric, and in which host shifts occur relatively infrequently in relation to speciation events. (b) Distribution of host taxa when speciation is mainly associated with host shifts. Note that only two host shifts are needed to explain current host-plant associations in a, whereas a minimum of six changes are needed to produce the pattern in b, although the number of speciation events is eight in both cases.
Nyman et al. BMC Evolutionary Biology 2010 10:266 doi:10.1186/1471-2148-10-266