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Anim Cogn

Title:		Quantity discrimination in Tenebrio molitor: evidence of numerosity discrimination in an invertebrate?
Author(s):		Carazo P; Font E; Forteza-Behrendt E; Desfilis E;
Address:		"Instituto Cavanilles de Biodiversidad y Biologia Evolutiva, Universidad de Valencia, Valencia, Spain. pau.carazo@uv.es"
Journal Title:		Anim Cogn
Year:		2009
Volume:		20090101
Issue:		3
Page Number:		463 - 470
DOI:		10.1007/s10071-008-0207-7
ISSN/ISBN:		1435-9456 (Electronic) 1435-9448 (Linking)
Abstract:		"Numerosity discrimination, the ability to distinguish between sets with more and less items, is recognised as the foundation for higher numerical abilities. Understanding numerosity discrimination from a comparative perspective is hence pivotal in tracing the evolution of numerical representation systems. However, numerosity discrimination has been well studied only in vertebrates, where two innate systems of number representation have been described: an 'analog magnitude system' used to discriminate among numerosities by representing them as cardinal magnitudes and a 'parallel individualisation system' that allows precise discrimination among small arrays of items (< or =4) by representing objects individually. We investigated the existence of quantity discrimination in an insect species (Tenebrio molitor) by using a spontaneous two-choice procedure in which males were exposed to substrates bearing odours from different numbers of females (< or =4) in increasing numerosity ratios (1:4, 1:3 and 1:2). We show that males can discriminate sources of odours reflecting 1 versus 4 and 1 versus 3 females, but not 2 versus 4 or 1 versus 2, indicating that T. molitor males exhibit a marked preference for sources reflecting more female donors only when numerosity ratios are below 1:2. We discuss the functional significance of this finding and whether our pattern of results could be best explained by summation of a non-numerical continuous variable or by the existence of a numerosity discrimination mechanism with an operational signature ratio of 1:2"
Keywords:		Animal Communication Animals *Choice Behavior Discrimination Learning/*physiology Female Male *Mathematical Concepts Olfactory Perception/*physiology Pheromones Tenebrio/*physiology;
Notes:		"MedlineCarazo, P Font, E Forteza-Behrendt, E Desfilis, E eng Research Support, Non-U.S. Gov't Germany 2009/01/02 Anim Cogn. 2009 May; 12(3):463-70. doi: 10.1007/s10071-008-0207-7. Epub 2009 Jan 1"