Volume 92, No. 3 September 2017 THE QUARTERLY REVIEW of Biology INORDINATE FONDNESS MULTIPLIED AND REDISTRIBUTED: THE NUMBER OF SPECIES ON EARTH AND THE NEW PIE OF LIFE Brendan B. Larsen* Department of Ecology and Evolutionary Biology, University of Arizona Tucson, Arizona 85721-0081 USA eail:
[email protected] Elizabeth C. Miller Department of Ecology and Evolutionary Biology, University of Arizona Tucson, Arizona 85721-0081 USA e-mail:
[email protected] Matthew K. Rhodes Department of Ecology and Evolutionary Biology, University of Arizona Tucson, Arizona 85721-0081 USA e-mail:
[email protected] John J. Wiens† Department of Ecology and Evolutionary Biology, University of Arizona Tucson, Arizona 85721-0081 USA e-mail:
[email protected] keywords arthropods, bacteria, biodiversity, cryptic species, parasites, species richness * Authorship order is alphabetical † Corresponding author The Quarterly Review of Biology, September 2017, Vol. 92, No. 3 Copyright © 2017 by The University of Chicago Press. All rights reserved. 0033-5770/2017/9203-0001$15.00 229 This content downloaded from 128.196.198.060 on August 25, 2017 09:19:00 AM All use subject to University of Chicago Press Terms and Conditions (http://www.journals.uchicago.edu/t-and-c). 230 THE QUARTERLY REVIEW OF BIOLOGY Volume 92 abstract The number of species on Earth is one of the most fundamental numbers in science, but one that remains highly uncertain. Clearly, more species exist than the present number of formally described spe- cies (approximately 1.5 million), but projected species numbers differ dramatically among studies. Re- cent estimates range from about 2 million species to approximately 1 trillion, but most project around 11 million species or fewer.