Abstract
The radiation of flowering plants in the mid-Cretaceous transformed landscapes and is widely believed to have fuelled the radiations of major groups of phytophagous insects. An excellent group to test this assertion is the scale insects (Coccomorpha: Hemiptera), with some 8,000 described Recent species and probably the most diverse fossil record of any phytophagous insect group preserved in amber. We used here a total-evidence approach (by tip-dating) employing 174 morphological characters of 73 Recent and 43 fossil taxa (48 families) and DNA sequences of three gene regions, to obtain divergence time estimates and compare the chronology of the most diverse lineage of scale insects, the neococcoid families, with the timing of the main angiosperm radiation. An estimated origin of the Coccomorpha occurred at the beginning of the Triassic, about 245 Ma [228–273], and of the neococcoids 60 million years later [210–165 Ma]. A total-evidence approach allows the integration of extinct scale insects into a phylogenetic framework, resulting in slightly younger median estimates than analyses using Recent taxa, calibrated with fossil ages only. From these estimates, we hypothesise that most major lineages of coccoids shifted from gymnosperms onto angiosperms when the latter became diverse and abundant in the mid- to Late Cretaceous.
Highlights
Living insect species that feed on vascular plants comprise some 40% of the described insect diversity[1], and so it appears that plants have had a profound effect on the diversification of insects
We explored the diversification of a major group of phytophagous insects, the scale insects (Hemiptera: Coccomorpha), of which 97% of the living species feed on angiosperms, and the group as a whole has a superb fossil record for the past 130 million years
The calibrations were based on Aphidomorpha and Coccomorpha fossil records ranging from 250 to 45 million years (Table S3)
Summary
Living insect species that feed on vascular plants comprise some 40% of the described insect diversity[1], and so it appears that plants have had a profound effect on the diversification of insects. Good examples include the hyperdiverse weevils (Coleoptera: Curculionoidea)[3] and the Lepidoptera[1,4], the latter the largest lineage of plant-feeding animals Since both of these insect groups are known to pre-date the first fossil angiosperms, and well preceded the angiosperm radiations in the mid-Cretaceous, it has commonly been inferred that the “colonization” or shift to angiosperms promoted insect diversification. We explored the diversification of a major group of phytophagous insects, the scale insects (Hemiptera: Coccomorpha), of which 97% of the living species feed on angiosperms, and the group as a whole has a superb fossil record for the past 130 million years. Based on recent discoveries of new coccoids in Cretaceous amber and their phylogenetic relationships[28], which we further explore here, the view of a Cretaceous radiation of Coccomorpha and Tertiary radiation of neococcoids needs to be revised
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