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Is hybridization a source of adaptive venom variation in rattlesnakes?

  • 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 genesVenomous 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.show moreshow less

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Metadaten
Author:Giulia Zancolli, Timothy G. Baker, Axel BarlowORCiDGND, Rebecca K. Bradley, Juan J. Calvete, Kimberley C. Carter, Kaylah de Jager, John Benjamin Owens, Jenny Forrester Price, Libia Sanz, Amy Scholes-Higham, Liam Shier, Liam Wood, Catharine E. Wüster, Wolfgang Wüster
URN:urn:nbn:de:kobv:517-opus4-407595
Parent Title (English):Toxins
Subtitle (English):a test, using a crotalus scutulatus × viridis hybrid zone in southwestern New Mexico
Series (Serial Number):Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe (443)
Document Type:Postprint
Language:English
Date of first Publication:2018/06/19
Year of Completion:2016
Publishing Institution:Universität Potsdam
Release Date:2018/06/19
Tag:Crotalus; Mojave toxin; adaptation; evolution; hybridization; introgression; molecular evolution; venom
Pagenumber:16
Source:MDPI Toxins 8 (2016); DOI: 10.3390/toxins8060188
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät
Mathematisch-Naturwissenschaftliche Fakultät / Institut für Biochemie und Biologie
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Peer Review:Referiert
Publication Way:Open Access
Grantor:Multidisciplinary Digital Publishing Institute (MDPI)
Licence (German):License LogoCreative Commons - Namensnennung, 4.0 International