title: Ancient origin of high taxonomic richness among insects.
abstract: Insects are a hyper-diverse group, comprising nearly three-quarters of all named animal species on the Earth, but the environmental drivers of their richness and the roles of ecological interactions and evolutionary innovations remain unclear. Previous studies have argued that family-level insect richness increased continuously over the evolutionary history of the group, but inclusion of extant family records artificially inflated the relative richness of younger time intervals. Here we apply sampling-standardization methods to a species-level database of fossil insect occurrences, removing biases present in previous richness curves. We show that insect family-richness peaked 125 Ma and that Recent values are only 1.5-3 times as high as the Late Palaeozoic. Rarefied species-richness data also tentatively suggest little or no net increase in richness over the past 125 Myr. The Cretaceous peak in family richness was coincident with major radiations within extant groups but occurred prior to extinctions within more basal groups. Those extinctions may in part be linked to mid-Cretaceous floral turnover following the evolution of flowering plants. Negligible net richness change over the past 125 Myr implies that major radiations within extant groups were offset by reduced richness within groups that are now relict or extinct.
authors: Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA mclapham@ucsc.edu.
authors: Matthew E
authors: http://orcid.org/0000-0003-4867-7304
authors: ME
authors: Clapham
authors: Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA.
authors: Jered A
authors: JA
authors: Karr
authors: Department of Biology, University of York, York YO10 5YW, UK Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK Department of Natural Sciences, National Museum of Scotland, Chambers Street, Edinburgh, Midlothian EH1 1JF, UK.
authors: David B
authors: DB
authors: Nicholson
authors: Department of Natural Sciences, National Museum of Scotland, Chambers Street, Edinburgh, Midlothian EH1 1JF, UK.
authors: Andrew J
authors: AJ
authors: Ross
authors: Department of Biology, University of York, York YO10 5YW, UK.
authors: Peter J
authors: PJ
authors: Mayhew
mesh_terms: D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D053476:Extinction, Biological; D005580:Fossils; D007313:Insecta / Q000502:physiology*; D010163:Paleontology
keywords: biodiversity; evolutionary radiation; insecta