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Toxins 2019, 11(2), 93;

Venom in Furs: Facial Masks as Aposematic Signals in a Venomous Mammal

Nocturnal Primate Research Group, Faculty of Humanities and Social Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
Faculty of Forestry, Universitas Gadjah Madah, Yogyakarta 55281, Indonesia
Department of Anthropology, Boston University, Boston, MA 02215, USA
Author to whom correspondence should be addressed.
Received: 21 December 2018 / Revised: 30 January 2019 / Accepted: 31 January 2019 / Published: 5 February 2019
(This article belongs to the Special Issue Evolutionary Ecology of Venom)
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The function of colouration in animals includes concealment, communication and signaling, such as the use of aposematism as a warning signal. Aposematism is unusual in mammals, and exceptions help us to understand its ecology and evolution. The Javan slow loris is a highly territorial venomous mammal that has a distinctive facial mask and monochromatic vision. To help understand if they use aposematism to advertise their venom to conspecifics or predators with different visual systems, we studied a population in Java, Indonesia. Using ImageJ, we selected colours from the facial masks of 58 individuals, converted RBG colours into monochromatic, dichromatic and trichromatic modes, and created a contrast index. During 290 captures, we recorded venom secretion and aggressiveness. Using Non-metric Multidimensional Scaling and generalised additive models for location, scale and shape, we found that young slow lorises differ significantly from adults, being both more contrasting and more aggressive, with aggressive animals showing fewer wounds. We suggest aposematic facial masks serve multiple purposes in slow lorises based on age. Change in colouration through development may play a role in intraspecific competition, and advertise toxicity or aggressiveness to competitors and/or predators in juveniles. Aposematic signals combined with intraspecific competition may provide clues to new venomous taxa among mammals. View Full-Text
Keywords: colouration; concealment; crypsis; intraspecific competition; Nycticebus; predation; visual system colouration; concealment; crypsis; intraspecific competition; Nycticebus; predation; visual system

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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 (CC BY 4.0).

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Nekaris, K. .-I.; Weldon, A.; Imron, M.A.; Maynard, K.Q.; Nijman, V.; Poindexter, S.A.; Morcatty, T.Q. Venom in Furs: Facial Masks as Aposematic Signals in a Venomous Mammal. Toxins 2019, 11, 93.

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