Is hybridization a source of adaptive venom variation in rattlesnakes? A test, using a crotalus scutulatus × viridis hybrid zone in Southwestern New Mexico

Zancolli, G., Baker, T.G., Barlow, A. ORCID: 0000-0002-5532-9458, Bradley, R.K., Calvete, J.J., Carter, K.C., De Jager, K., Owens, J.B., Price, J.F., Sanz, L., Scholes-Higham, A., Shier, L., Wood, L., Wüster, C.E. and Wüster, W., 2016. Is hybridization a source of adaptive venom variation in rattlesnakes? A test, using a crotalus scutulatus × viridis hybrid zone in Southwestern New Mexico. Toxins, 8 (6): 188. ISSN 2072-6651

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Abstract

Venomous snakes often display extensive variation in venom composition both between and within species. However, the mechanisms underlying the distribution of different toxins and venom types among populations and taxa remain insufficiently known. Rattlesnakes (Crotalus, Sistrurus) display extreme inter- and intraspecific variation in venom composition, centered particularly on the presence or absence of presynaptically neurotoxic phospholipases A2 such as Mojave toxin (MTX). Interspecific hybridization has been invoked as a mechanism to explain the distribution of these toxins across rattlesnakes, with the implicit assumption that they are adaptively advantageous. Here, we test the potential of adaptive hybridization as a mechanism for venom evolution by assessing the distribution of genes encoding the acidic and basic subunits of Mojave toxin across a hybrid zone between MTX-positive Crotalus scutulatus and MTX-negative C. viridis in southwestern New Mexico, USA. Analyses of morphology, mitochondrial and single copy-nuclear genes document extensive admixture within a narrow hybrid zone. The genes encoding the two MTX subunits are strictly linked, and found in most hybrids and backcrossed individuals, but not in C. viridis away from the hybrid zone. Presence of the genes is invariably associated with presence of the corresponding toxin in the venom. We conclude that introgression of highly lethal neurotoxins through hybridization is not necessarily favored by natural selection in rattlesnakes, and that even extensive hybridization may not lead to introgression of these genes into another species.

Item Type: Journal article
Publication Title: Toxins
Creators: Zancolli, G., Baker, T.G., Barlow, A., Bradley, R.K., Calvete, J.J., Carter, K.C., De Jager, K., Owens, J.B., Price, J.F., Sanz, L., Scholes-Higham, A., Shier, L., Wood, L., Wüster, C.E. and Wüster, W.
Publisher: MDPI AG
Date: June 2016
Volume: 8
Number: 6
ISSN: 2072-6651
Identifiers:
NumberType
10.3390/toxins8060188DOI
1238801Other
Rights: © 2016 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/).
Divisions: Schools > School of Science and Technology
Depositing User: Linda Sullivan
Date Added: 27 Nov 2019 16:46
Last Modified: 27 Nov 2019 16:46
URI: http://irep.ntu.ac.uk/id/eprint/38591

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