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International Journal of Ecology
Volume 2012 (2012), Article ID 506957, 8 pages
Review Article

Of “Host Forms” and Host Races: Terminological Issues in Ecological Speciation

Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634, USA

Received 31 July 2011; Accepted 26 October 2011

Academic Editor: Zachariah Gompert

Copyright © 2012 Daniel J. Funk. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Successful communication and accurate inferences in science depend on the common understanding and consistent usage of the terms we apply to concepts of interest. Likewise, new terminology is required when important concepts have gone unnamed. Here, I focus on terminological issues about biological variation and ecological speciation, especially in herbivorous insects but also more generally. I call for the more restricted use of concepts that have sometimes been misapplied, and thus caution against synonymizing ecological speciation with sympatric speciation and the unwarranted invocation of “host races” to describe herbivorous insect differentiation. I also call for the qualified application of terms for different kinds of biological variation and for host range when confronting uncertainty. Among other “missing terms” introduced here is “host form,” a generic term describing any case of host-associated differences for which current evidence does not allow diagnosis of the specific kind of variation. Embracing the use of host form should free host race from its current overapplication. Finally, I present a case study in which Neochlamisus leaf beetle populations previously described as host forms are hereby declared to be host races, based on accumulated evidence supporting each of the associated criteria.