title: Biological factors contributing to bark and ambrosia beetle species diversification.
abstract: The study of species diversification can identify the processes that shape patterns of species richness across the tree of life. Here, we perform comparative analyses of species diversification using a large dataset of bark beetles. Three examined covariates-permanent inbreeding (sibling mating), fungus farming, and major host type-represent a range of factors that may be important for speciation. We studied the association of these covariates with species diversification while controlling for evolutionary lag on adaptation. All three covariates were significantly associated with diversification, but fungus farming showed conflicting patterns between different analyses. Genera that exhibited interspecific variation in host type had higher rates of species diversification, which may suggest that host switching is a driver of species diversification or that certain host types or forest compositions facilitate colonization and thus allopatric speciation. Because permanent inbreeding is thought to facilitate dispersal, the positive association between permanent inbreeding and diversification rates suggests that dispersal ability may contribute to species richness. Bark beetles are ecologically unique; however, our results indicate that their impressive species diversity is largely driven by mechanisms shown to be important for many organism groups.
authors.affiliation: Department of Natural History, University Museum of Bergen, University of Bergen, P.O. box 7800,, 5020, Bergen, Norway.
authors.forename: Jostein
authors.initials: J
authors.lastname: Gohli
authors.affiliation: Department of Biology, University of Bergen, P.O. box 7800,, 5020, Bergen, Norway.
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Kirkendall
authors.affiliation: Department of Entomology, Michigan State University, 288 Farm Lane, East Lansing, Michigan, 48824.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Smith
authors.affiliation: Department of Entomology, Michigan State University, 288 Farm Lane, East Lansing, Michigan, 48824.
authors.forename: Anthony I
authors.initials: AI
authors.lastname: Cognato
authors.affiliation: School of Forest Resources and Conservation and the Department of Entomology, University of Florida, Gainesville, Florida, 32611.
authors.forename: Jiri
authors.initials: J
authors.lastname: Hulcr
authors.affiliation: Department of Natural History, University Museum of Bergen, University of Bergen, P.O. box 7800,, 5020, Bergen, Norway.
authors.forename: Bjarte H
authors.initials: BH
authors.lastname: Jordal
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001685:Biological Factors; D001517:Coleoptera / Q000235:genetics*; D004463:Ecology; D005658:Fungi; D049810:Genetic Speciation
chemical_list: D001685:Biological Factors
keywords: Bark beetles; Scolytinae; fungus farming; host specificity; inbreeding; speciation; symbiosis