Data from: Plant–insect interactions: double-dating associated insect and plant lineages reveals asynchronous radiations

An increasing number of plant-insect studies using phylogenetic analysis
suggest that cospeciation events are rare in plant–insect systems.
Instead, nonrandom patterns of phylogenetic congruence are produced by
phylogenetically conserved host switching (to related plants) or tracking
of particular resources or traits (e.g., chemical). The dominance of host
switching in many phytophagous insect groups may make the detection of
genuine cospeciation events difficult. One important test of putative
cospeciation events is to verify whether reciprocal speciation is
temporally plausible. We explored techniques for double-dating of both
plant and insect phylogenies. We use dated molecular phylogenies of a
psyllid (Hemiptera)–Genisteae (Fabaceae) system, a predominantly
monophagous insect–plant association widespread on the Atlantic
Macaronesian islands. Phylogenetic reconciliation analysis suggests high
levels of parallel cladogenesis between legumes and psyllids. However,
dating using molecular clocks calibrated on known geological ages of the
Macaronesian islands revealed that the legume and psyllid radiations were
not contemporaneous but sequential. Whereas the main plant radiation
occurred some 8 million years ago, the insect radiation occurred about 3
million years ago. We estimated that >60% of the psyllid speciation
has resulted from host switching between related hosts. The only evidence
for true cospeciation is in the much more recent and localized radiation
of genistoid legumes in the Canary Islands, where the psyllid and legume
radiations have been partially contemporaneous. The identification of
specific cospeciation events over this time period, however, is hindered
by the phylogenetic uncertainty in both legume and psyllid phylogenies due
to the apparent rapidity of the species radiations.