Field Herp Forum

Evolution of Venom and the 'Red Queen Hypothesis'
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Author:  MCHerper [ December 7th, 2017, 10:23 am ]
Post subject:  Evolution of Venom and the 'Red Queen Hypothesis'

I'm currently teaching a high school toxicology class and we are about to begin discussing venom and the evolution of venom. I'm interested in finding out more about the evolution of venom from the perspective of the coevolution of venom and the prey, namely how the complexity of venom might be a reflection of the adaptations or resistance of the prey. Can anyone share info or point me in the right direction? Thank you!

Author:  Richard F. Hoyer [ December 7th, 2017, 11:46 am ]
Post subject:  Re: Evolution of Venom and the 'Red Queen Hypothesis'

As for the issue of co-evolution of a predator and it prey in relation to toxins, although not involving snake venom, I suggest you might look in to the
research published by Dr. Edmond (Butch) Brodie at Utah State U. involving the ‘venom’ produced by species of newts and their snake predators, mainly certain subspecies of the Common Garter Snake.

It is a very fascinating ‘story’. In this particular instance, it is the prey that produces the toxin and the predator that has evolved to cope with such toxins. And perhaps some citations in his publication may include reference to snake venom and adaptations involving prey species.

Richard F. Hoyer (Corvallis, Oregon)

Author:  Jimi [ December 7th, 2017, 12:31 pm ]
Post subject:  Re: Evolution of Venom and the 'Red Queen Hypothesis'

Steve (Stephen) MacKessy @ UNC-Greeley would be worth contacting. Try a phone call - he's smart, friendly, and utterly captivated by venoms...

Author:  regalringneck [ December 7th, 2017, 7:03 pm ]
Post subject:  Re: Evolution of Venom and the 'Red Queen Hypothesis'

suggest you use google scholar w/ your keywords, i recall there was work w/ pacific crotes & grnd squirrel venom resistance see:

Development of Antisnake Defenses in California Ground Squirrels (Spermophilus Beecheyi): II. Microevolutionary Effects of Relaxed Selection From Rattlesnakes

Authors: Richard G. Coss1; Kevin L. Gusé1; Naomie S. Poran1 and David G. Smith1
Source: Behaviour, Volume 124, Issue 1, pages 137 – 162 Publication Year : 1993
DOI: 10.1163/156853993X00542
ISSN: 0005-7959 E-ISSN: 1568-539X
Document Type: Research Article
Subjects: Biology
Abstract Full Text Media References(0) Cited By (21) Metrics
Nonvenomous Pacific gopher snakes (Pituophis melanoleucus catenifer) and venomous northern Pacific rattlesnakes (Crotalus viridis oreganus) have coexisted in a predator-prey relationship with California ground squirrels (Spermophilus beecheyi) for many thousands of generations. This long-term relationship has fostered in ground squirrels the evolution of antisnake defenses that consist of physiological resistance to rattlesnake venom and behavioral tactics of probing and harassing that might facilitate snake-species discrimination. Snake harassment by adults might also protect pups by interfering with snake hunting activities. Some ground squirrel populations have colonized habitats where rattlesnakes, but not gopher snakes, are rare or absent. Initial research indicates that squirrels experiencing relaxed selection from rattlesnakes are very aggressive toward their remaining nonvenomous snake predator, the gopher snake. Two experiments investigated the effects of relaxed selection from rattlesnakes by examining: 1) changes in level of venom resistance, 2) the reorganization of antisnake behaviors in lab-born pups and wild-caught adults from different sites, and 3) the role of natural experiences on the development of antisnake behavior in a rattlesnake-adapted population. Level of venom resistance was examined by an in vitro radioimmunoassay of serum-to-venom binding of two populations of Douglas ground squirrels (S. b. douglasii). The ancestors of one population are estimated to have experienced relaxed selection from rattlesnakes for about 9,000 years based on genetic distance and radiocarbon analyses. The antisnake behavior of 60-73 day-old lab-born pups from these two populations was video taped during presentations of a caged rattlesnake or gophcr snake for alternate 5-min trials in a seminatural laboratory setting. Two groups of wild-caught adult Beechey groundsquirrels (S. b. beecheyi) were studied using the same protocol for examining antisnake behavior. One group was obtained from a population that recently colonized a rattlesnake-rare site and exhibits moderate venom resistance. The second group came from a population that exhibits very low venom resistance and inhabits a rattlesnake-free site; relaxed selection from rattlesnakes for this population is estimated to span approximately 60,000 years. Comparisons of Douglas ground squirrels from rattlesnake-abundant and rettlesnakerare sites revealed that venom resistance declined approximately 59% after an estimated 9,000 years of relaxed selection from rattlesnakes. Lab-born Douglas pups from the same rattlesnake-rare site were more aggressive toward the gopher snake than toward the rattlesnake whereas pups from the population experiencing predation from both species of snake treated both snakes as similarly dangerous. Unlike pups, wild-caught adults from the rattesnake-adapted population harassed the rattlesnake more intensely than the gopher snake, a phenomenon that may reflect their experience with snakes in nature and larger body size that reduces their vulnerability to envenomation. Wild-caught Beechey ground squirrels that recently colonized a rattlesnake-rare site did not differentiate the rattlesnake and gopher snake whereas Beechey ground squirrels whose ancestors have experienced prolonged relaxed selection from rattlesnakes were more aggressive toward the gopher snake. Consistent with previous findings, prolonged relaxed selection from rattlesnakes, but not gopher snakes, appears to have reduced the inhibition to harass large gopher snakes. This microevolutionary shift in increased aggressiveness toward the gopher snake could result from the virtual absence of any risk in misidentifying rattlesnakes from gopher snakes.
Affiliations: 1: Departments of Psychology and Anthropology, University of California, Davis, California 95616 U.S.A

Another fascinating case in this arena are the virginanus opossums, i read a report from brazil where 1/2 the tropical crotes didnt even attempt to bite when eaten tail first by these ancient monsters ... ??? rxr

Author:  mfb [ December 8th, 2017, 8:30 am ]
Post subject:  Re: Evolution of Venom and the 'Red Queen Hypothesis'

A great topic for biology students to learn about!

I teach about this topic in my herpetology class at Case Western Reserve University. If you PM me your email address, I would be happy to send you some of my slides, and pdfs of the scientific papers from the studies I discuss in class. There are some very neat studies out there, for example showing geographic variation in venom composition associated with populations of the same species in which some are adapted to eat invertebrates, and some adapted to eat vertebrates.

From an applied perspective, there is also research showing how geographic variation in snake venom composition affect antivenom effectiveness.



Author:  MCHerper [ December 11th, 2017, 7:04 am ]
Post subject:  Re: Evolution of Venom and the 'Red Queen Hypothesis'

Thank you all for the info! Mfb, I'll send a PM shortly.

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