Explaining the disparity of species richness across the tree of life is one of the great challenges in evolutionary biology. Some lineages are exceptionally species rich, while others are relatively species poor. One explanation for heterogeneity among clade richness is that older clades are more species rich because they have had more time to accrue diversity than younger clades. Alternatively, disparity in species richness may be due to among-lineage diversification rate variation. Here we investigate diversification in water scavenger beetles (Hydrophilidae), which vary in species richness among major lineages by as much as 20 fold. Using a time-calibrated phylogeny and comparative methods, we test for a relationship between clade age and species richness and for shifts in diversification rate in hydrophilids. We detected a single diversification rate increase in Megasternini, a relatively young and species rich clade whose diversity might be explained by the stunning diversity of ecological niches occupied by this clade. We find that Amphiopini, an old clade, is significantly more species poor than expected, possibly due to its restricted geographic range. The remaining lineages show a correlation between species richness and clade age, suggesting that both clade age and variation in diversification rates explain the disparity in species richness in hydrophilids. We find little evidence that transitions between aquatic, semiaquatic, and terrestrial habitats are linked to shifts in diversification rates.

Department of Ecology and Evolutionary Biology University of Kansas Lawrence Kansas United States of America; Division of Entomology Biodiversity Institute University of Kansas Lawrence Kansas United States of America

Department of Entomology National Museum Prague Czech Republic; Department of Zoology Faculty of Sciences Charles University Prague Czech Republic

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Farrell BD (1998) “Inordinate Fondness” Explained: Why Are There So Many Beetles? Science 281: 555–559. PubMed

Hutchinson GE (1959) Homage to Santa Rosalia or Why Are There So Many Kinds of Animals? The American Naturalist 93: 145–159.

Fisher AG (1960) Latitudinal variations in organic diversity. Evolution 14: 64–81.

Pyron RA, Burbrink FT (2013) Phylogenetic estimates of speciation and extinction rates for testing ecological and evolutionary hypotheses. Trends in ecology & evolution (Personal edition) 28: 729–736. PubMed

Rabosky DL, Slater GJ, Alfaro ME (2012) Clade Age and Species Richness Are Decoupled Across the Eukaryotic Tree of Life. PLOS Biol 10: e1001381. PubMed PMC

Wiens BJohn J (2011) The Causes Of Species Richness Patterns Across Space, Time, And Clades And The Role Of “Ecological Limits”. The Quarterly Review of Biology 86: 75–96. PubMed

McPeek MA, Brown JM (2007) Clade age and not diversification rate explains species richness among animal taxa. The American Naturalist 169: E97–E106. PubMed

Rabosky DL, Donnellan SC, Talaba AL, Lovette IJ (2007) Exceptional among-lineage variation in diversification rates during the radiation of Australia’s most diverse vertebrate clade. Proceedings of the Royal Society B-Biological Sciences 274: 2915–2923. PubMed PMC

Rabosky DL (2009) Ecological limits and diversification rate: alternative paradigms to explain the variation in species richness among clades and regions. Ecology Letters 12: 735–743. PubMed

Rabosky DL (2010) Primary Controls on Species Richness in Higher Taxa. Systematic Biology 59: 634–645. PubMed

Rabosky DL (2013) Diversity-Dependence, Ecological Speciation, and the Role of Competition in Macroevolution. Annual Review of Ecology, Evolution, and Systematics 44: null

Ricklefs RE, Schwarzbach AE, Renner SS (2006) Rate of lineage origin explains the diversity anomaly in the world’s mangrove vegetation. American Naturalist 168: 805–810. PubMed

Magallon S, Sanderson MJ (2001) Absolute diversificatoin rates in Angiosperm clades. Evolution 55: 1762–1780. PubMed

Ricklefs RE (2003) Global diversification rates of passerine birds. Proceedings of the Royal Society of London Series B: Biological Sciences 270: 2285–2291. PubMed PMC

Ricklefs RE, Losos JB, Townsend TM (2007) Evolutionary diversification of clades of squamate reptiles. Journal of Evolutionary Biology 20: 1751–1762. PubMed

Stephens PR, Wiens JJ (2003) Explaining Species Richness from Continents to Communities: The Time-for-Speciation Effect in Emydid Turtles. The American Naturalist 161: 112–128. PubMed

Gamble T, Bauer AM, Colli GR, Greenbaum E, Jackman TR, et al. (2011) Coming to America: multiple origins of New World geckos. Journal of Evolutionary Biology 24: 231–244. PubMed PMC

Ribera I, Vogler AP, Balke M (2008) Phylogeny and diversification of diving beetles (Coleoptera: Dytiscidae). Cladistics 24: 563–590. PubMed

Short AEZ, Fikáček M (2013) Molecular Phylogeny, Evolution, and Classification of the Hydrophilidae (Coleoptera). Systematic Entomology 38: 723–752.

Bernhard D, Schmidt C, Korte A, Fritzsch G, Beutel RG (2006) From terrestrial to aquatic habitats and back again – molecular insights into the evolution and phylogeny of Hydrophiloidea (Coleoptera) using multigene analyses. Zoologica Scripta 35: 597–606.

Fikáček M, Prokin AA, Angus RB, Ponomarenko AG, Yue Y, et al. (2012) Phylogeny and the fossil record of the Helophoridae reveal Jurassic origin of modern hydrophiloid lineages (Coleoptera: Polyphaga). Systematic Entomology 37: 420–447.

Ribera I, Barraclough TG, Vogler AP (2001) The effect of habitat type on speciation rates and range movements in aquatic beetles: inferences from species-level phylogenies. Molecular Ecology 10: 721–735. PubMed

Ribera I, Foster GN, Vogler AP (2003) Does habitat use explain large scale species richness patterns of aquatic beetles in Europe? Ecography 26: 145–152.

Vrba ES (1987) Ecology in relation to speciation rates: some case histories of Miocene-Recent mammal clades. Evolutionary Ecology 1: 283–300.

Bloom DD, Weir JT, Piller KR, Lovejoy NR (2013) Do freshwater fishes diversify faster than marine fishes? A test using state-dependent diversification analyses and molecular phylogenetics of New World Silversides (Atherinopsidae). Evolution 67: 2040–2057. PubMed

Benton MJ (2009) The Red Queen and the Court Jester: Species diversity and the role of biotic and abiotic factors through time. Science 323: 728–732. PubMed

Alfaro ME, Santini F, Brock CD (2007) Do reefs drive diversification in marine teleosts? Evidence from the pufferfish and their allies (Order Tetraodontiformes). Evolution 61: 2104–2126. PubMed

Sequeira AS, Lanteri AA, Albelo R, Bhattacharya S, Sijapati M (2008) Colonization history, ecological shifts and diversification in the evolution of endemic Galapagos weevils. Molecular Ecology 17: 1089–1107. PubMed

McPeek MA (2007) The macroevolutionary consequences of ecological differences among species. Palaeontology 50: 111–129.

Moore BR, Donoghue MJ (2009) A Bayesian approach for evaluating the impact of historical events on rates of diversification. Proceedings of the National Academy of Sciences of the United States of America 106: 4307–4312. PubMed PMC

Donoghue MJ (2008) A phylogenetic perspective on the distribution of plant diversity. Proceedings of the National Academy of Sciences 105: 11549–11555. PubMed PMC

Drummond AJ, Suchard MA Xie D Rambaut A, (2012) Bayesian phylogenetics with BEAUti and the BEAST 1.7. Molecular Biology and Evolution. PubMed PMC

Fikáček M, Prokin A, Yan E, Yue Y, Wang B, et al. (2014) Modern hydrophilid clades present and widespread in the Late Jurassic and Early Cretaceous (Coleoptera: Hydrophiloidea: Hydrophilidae). Zoological Journal of the Linnean Society 170: 710–734.

Fikáček M, Prokop J, Nel A (2010) Fossil water scavenger beetles of the subtribe Hydrobiusina (Coleoptera: Hydrophilidae) from the Upper Oligocene locality of Aix-en-Provence. Acta Entomologica Musei Nationalis Pragae 50: 445–458.

Fikáček M, Engel MS (2011) An aquatic water scavenger beetle in Early Miocene amber from the Dominican Republic (Coleoptera: Hydrophilidae). Annales Zoologici 61: 621–628.

Kubisz D (2000) Fossil beetles (Coleoptera) from Baltic amber in the collection of the Museum of Natural History of ISEA in Kraków. Polish Journal of Entomology 69: 225–230.

Fikáček M, Prokin AA, Angus RB, Ponomarenko AG, Yue Y, et al. (2012) Revision of Mesozoic fossils of the helophorid lineage of the superfamily Hydrophiloidea (Coleoptera: Polyphaga). Acta Entomologica Musei Nationalis Pragae 52: 89–127.

Drummond AJ, Rambaut A (2007) BEAST: Bayesian evolutionary analysis by sampling trees. BMC Evolutionary Biology 7: 214. PubMed PMC

Alfaro ME, Santini F, Brock C, Alamillo H, Dornburg A, et al. (2009) Nine exceptional radiations plus high turnover explain species diversity in jawed vertebrates. Proceedings of the National Academy of Sciences of the United States of America 106: 13410–13414. PubMed PMC

Rabosky DL (2010) Extinction rates should not be estimated from molecular phylogenies. Evolution 6: 1816–1824. PubMed

Harmon LJ, Weir JT, Brock CD, Glor RE, Challenger W (2008) GEIGER: investigating evolutionary radiations. Bioinformatics 24: 129–131. PubMed

Hamilton Andrew J, Basset Y, Benke Kurt K, Grimbacher Peter S, Miller Scott E, et al. (2010) Quantifying Uncertainty in Estimation of Tropical Arthropod Species Richness. The American Naturalist 176: 90–95. PubMed

Maddison WP, Maddison DR, (2011) Mesquite: a modular system for evolutionary analysis. 2.75 ed.

Pagel M (1999) The maximum likelihood approach to reconstructing ancestral character states of discrete characters on phylogenies. Systematic Biology 48: 612–622.

Hunt T, Bergsten J, Levkanicova Z, Papadopoulou A, John OS, et al. (2007) A comprehensive phylogeny of beetles reveals the evolutionary origins of a superradiation. Science 318: 1913–1916. PubMed

McKenna D, Farrell B (2009) Beetles (Coleoptera). In: Hedges SB, Kumar S, editors. The Timetree of Life: Oxford University Press. 278–289.

Prokin AA (2009) New water scavenger beetles (Coleoptera: Hydrophilidae) from the Mesozoic of Mongolia. Paleontological Journal 43: 660–663.

Fikáček M, Prokin A, Yan E, Yue Y, Wang B, et al. (in press) Modern hydrophilid clades present and widespread in the Late Jurassic and Early Cretaceous (Coleoptera: Hydrophiloidea: Hydrophilidae). Zoological Journal of the Linnean Society.

Labandeira CC, Sepkoski JJ (1993) Insect diversity in the fossil record. Science 261: 310–315. PubMed

Betancur-R R, Ortí G, Stein AM, Marceniuk AP, Alexander Pyron R (2012) Apparent signal of competition limiting diversification after ecological transitions from marine to freshwater habitats. Ecology Letters 15: 822–830. PubMed

Bloom DD, Lovejoy NR (2012) Molecular phylogenetics reveals a pattern of biome conservatism in New World anchovies (Family Engraulidae). Journal of Evolutionary Biology 25: 701–715. PubMed

Crisp MD, Arroyo MTK, Cook LG, Gandolfo MA, Jordan GJ, et al. (2009) Phylogenetic biome conservatism on a global scale. Nature 458: 754–U790. PubMed

Vermeij GJ, Dudley R (2000) Why are there so few evolutionary transitions between aquatic and terrestrial ecosystems? Biological Journal of the Linnean Society 70: 541–554.

Ribera I (2008) Habitat constraints and the generation of diversity in freshwater macroinvertebrates. In: Lancaster J, Briers RA, editors. Aquatic Insects: Challenges to Populations. UK: CAB International. 289–311.

Martin CH, Wainwright PC (2013) Multiple Fitness Peaks on the Adaptive Landscape Drive Adaptive Radiation in the Wild. Science 339: 208–211. PubMed

Svensson EI, Calsbeek R (2012) The Adaptive Landscape in Evolutionary Biology. Oxford: Oxford University Press.

de Queiroz A (2002) Contingent Predictability in Evolution: Key Traits and Diversification. Systematic Biology 51: 917–929. PubMed

Bininda-Emonds ORP, Cardillo M, Jones KE, MacPhee RDE, Beck RMD, et al. (2007) The delayed rise of present-day mammals. Nature 446: 507–512. PubMed

Wainwright PC, Smith WL, Price SA, Tang KL, Sparks JS, et al. (2012) The Evolution of Pharyngognathy: A Phylogenetic and Functional Appraisal of the Pharyngeal Jaw Key Innovation in Labroid Fishes and Beyond. Systematic Biology 61: 1001–1027. PubMed

Fikáček M, Short AEZ (2010) A revision of the Neotropical genus Sacosternum Hansen (Coleoptera: Hydrophilidae: Sphaeridiinae). Zootaxa 2538: 1–37.

Smetana A (1978) Revision of the subfamily Sphaeridiinae of America north of Mexico (Coleoptera: Hydrophilidae). Memoirs of the Entomological Society of Canada 105: 1–292.

Jablonski D (2008) Species selection: Theory and data. Annual Review of Ecology, Evolution, and Systematics 39: 501–524.

Jablonski D, Hunt G (2006) Larval ecology, geographic range, and species survivorship in Cretaceous mollusks: Organismic versus species-level explanations. American Naturalist 168: 556–564. PubMed

Rabosky DL, McCune AR (2010) Reinventing species selection with molecular phylogenies. Trends in Ecology & Evolution 25: 68–74. PubMed

Rabosky DL (2009) Ecological limits on clade diversification in higher taxa. American Naturalist 173: 662–674. PubMed

Schluter D (2000) The Ecology of Adaptive Radations: Oxford University Press.

Yoder JB, Clancey E, Roches SD, Eastman JM, Gentry L, et al. (2010) Ecological opportunity and the origin of adaptive radiations. Journal of Evolutionary Biology 23: 1581–1596. PubMed

Burbrink FT, Pyron RA (2010) How Does Ecological Opportunity Influence Rates of Speciation, Extinction, and Morphological Diversification in New World Ratsnakes (Tribe Lampropeltini)? Evolution 64: 934–943. PubMed

Pyron RA, Burbrink FT (2012) Extinction, ecological opportunity, and the origins of global snake diversity. Evolution 66: 163–178. PubMed

Parent CE, Crespi BJ (2009) Ecological Opportunity in Adaptive Radiation of Galapagos Endemic Land Snails. The American Naturalist 174: 898–905. PubMed

Maddison WP, Midford PE, Otto SP (2007) Estimating a binary character’s effect on speciation and extinction. Systematic Biology 56: 701–710. PubMed

Rabosky DL, Lovette IJ (2008) Density-dependent diversification in North American wood warblers. Proceedings of the Royal Society B: Biological Sciences 275: 2363–2371. PubMed PMC

Minoshima Y, Hayashi M (2012) The first instar larva of Hydrobius pauper Sharp (Coleoptera, Hydrophilidae). Elytra, NS 2: 279–284.

Short AEZ, Fikáček M (2011) World catalogue of the Hydrophiloidea (Coleoptera): additions and corrections II (2006–2010). Acta Entomologica Musei Nationalis Pragae 51: 83–122.

Watts CHS (1998) Revision of Australian Amphiops Erichson, Allocotocerus Kraatz and Regimbartia Zaitzev (Coleoptera: Hydrophilidae). Records of the South Australian Museum 30: 93–106.

Short AEZ (2009) Description of Micramphiops gen. n. from Madagascar (Coleoptera: Hydrophilidae). Koleopterologische Rundschau 79: 189–195.

Ancient divergent evolution of specialized swimming modes in aquatic beetles