Most venomous species use their venom for the main purpose of prey capture. Over time venom composition and behaviours associated with venom producing species have evolved for specific functions, conservation of energy, and to be prey-specific. In certain venomous species they are found to be particularly more toxic to one type of prey. This is found in the mangrove snake (Boiga dendrophilia) with bird-specific toxins. Whereas the mangrove snake has specific toxins in its venom to be more lethal to one type of prey, Some venomous species diet will change their venom composition. An example of this is the Malayan pit viper (Calloselasma rhodostoma). In many venomous species it was found that envenomation has a high metabolic cost, which could be an important constraint on make-up and use of the venom. This would require the organism to either require more nutrients or adapt behavioural and physiological mechanisms due to the high energetic cost. Some examples of these mechanisms are: in several rattlesnakes the amount of venom injected correlated with the size of the prey; in certain spiders the amount of venom given is not associated with the size of the prey, but with the intensity or duration of the prey's movement; and in scorpions they have developed a pre-venom that is highly painful for low-threat encounters which requires low amounts of energy. Another challenge faced is prey-species becoming resistant over time to a particular venom. This was found in the California ground squirrel (Spermophilus Beecheyi) becoming resistant to the Northern Pacific rattlesnakes (Crotalus viridis oreganus) venom in that area (Benjamini Et al. 1987). With the all of these showing changes in individual species behaviour and venom composition it points to diet being one of the major drivers for the evolution of venom.
Benjamini, E. Coss, R. Poran, N. (1987) 'Resistance of
California ground squirrels (Spermophilus
beecheyi) to the venom of northern
Pacific rattlesnake (Crotalus viridis
oreganus): A study of adaptive variation' Toxicon, Vol 25, Iss. 7, Pgs. 767-777. Viewed 09 March 2014, < http://ac.els-cdn.com/0041010187901279/1-s2.0-0041010187901279-main.pdf?_tid=f9a02e3a-a770-11e3-bfde-00000aab0f27&acdnat=1394359121_c2a34a75d23ebbd3682b3bf2c1aec5e7>
Casewell, N. Fry, B. Harrison, R. Vonk, F. Wuster, W. (2013)
'Complex cocktails: the evolutionary novely of venoms' Trends in Ecology & Evolution, Vol 28, Iss. 4, Pgs. 219-229.
Viewed 09 March 2014, <http://ac.els-cdn.com/S0169534712002935/1-s2.0-S0169534712002935-main.pdf?_tid=aaa0568a-a72e-11e3-81b3-00000aab0f6c&acdnat=1394330642_c5b63a6ff8feea5a4907351e6a08d153>
Interesting and well-written. A nice look at the relationship between diet and venom. Good use of examples. Will you be looking at other venomous species, such as mammals?
ReplyDeleteI will mostly focus on spiders, scorpions, and snakes due to the amount of information available from these species. If there are examples I can provide of different venomous species I defiantly will! I will do at least one article on the five species of mammals that have venom.
ReplyDeleteCool post interesting stuff. I wonder how this is factored into the LD50 measurement if at all. I know they use mice as test subjects so we can use it to see how lethal the venom is to humans. I would say there would be some interesting results if they were to use other reptiles or birds.
ReplyDeletePS. Venomous mammals are really interesting.
I looked through many articles and did not find any of them relating the LD50 test to humans for birds and reptiles. I only found articles pertaining to the use of the LD50 test for the use of looking at the toxicology of the organism. I do not believe it would be a viable test to use birds and reptiles to see how lethal the venom is due to the difference of the species to humans.
ReplyDeleteI'm curious as to how the venom is specified towards birds or mammals. Do they attack different systems? Or is it just a sort of certain compounds affect species differently type deal?
ReplyDelete