Venom Resistance

The Perfect Generalist Predator: Venom Resistant? VENOM RESISTANT PREDATORS (Just a suggestion)
This paper aims to show that venom immune predators are essential for the evolution of the strongest venoms. It also will illustrate that the interaction of predators with venomous prey will be exaggerate coevolution for both the predator and the prey. This paper will also examine the specific adaptations that allow some mammals to exploit highly dangerous prey. VENOM IMMUNE PREDATORS ARE ESSENTIONAL FOR THE CO-EVOLUTION FOR BOTH PREDATOR AND PREY. THEIR RESISTANCE iS DUE TO SPECIFIC ADAPTIONS ALLOWING SOME MAMMELS TO EXPLOIT HIGHLY DANGEROUS PREY.
When Charles Darwin first proposed his ideas on the origins of species, he could not have grasped the true complexity of the interactions of predators and their prey. Science has advanced considerably on his theories over the past century with many of the greatest discoveries coming in the wake of the introduction of the thermal cycler and the polymerase chain reaction. Technology has brought the ability to look at organisms at the sub cellular level and beyond. The concept of coevolution examines the interaction of predator and prey but is different than evolution in that it proposes predators evolve along with their prey. For the purpose of this paper we will define predation as only those who kill free living individuals for food. Since we are looking at mammals, predators will refer primarily to carnivores and omnivores. Generally, predator evolution is slower than that of prey (Abrams, 1997). This relationship is due to the fact that the predator prey interaction is off balance in the direction of the predator. Should the outcome favor the predator the prey dies and a set or traits are removed from the population. The predator usually will survive the interaction with the prey. However, should the predator fail to capture prey enough times, they will starve and die or be killed by another predator. When the prey is dangerous, the prey has the ability to select against their predator.

The evolution of chemical defenses is common in the animal kingdom. Animals use foul smelling, foul tasting, and even poisonous chemicals to defeat predators. Chemicals are sometimes used for predation such as venom. Venom is a toxic substance that is injected into the tissue of the victim. This toxin travels through the bloodstream of the victim and wreaks havoc on bodily tissues. Reptile, Insects, and Arachnids are some of the most widely known venomous animals on the planet. A few mammals have venom secretions but are not widely known. The primary use for venom in the animal kingdom is offensive. Snakes use venom to kill prey and in many cases to begin the digestion process. Many snakes that are commonly known as harmless in fact have venom or venom like proteins in their saliva. Often their venom is very prey specific meaning it is harmless to all other organisms.
Nearly the entire family Herpestetidae carries the name mongoose. This family has expanded to world wide range due to human introductions and for the purpose of this paper we will concentrate on the genus Herpestes. These mongooses live from densely forested hills to open arid plains (Nowak, 1999. pp. 771-773). They may be diurnal or nocturnal and have an extensive wide diet. According to Nowak the species not immune to cobra venom but avoids being struck due to their superior agility and speed.
The Virginia opossum is one of the best adapted animals in North America (Nowak, 1999. pp. 31-33). Although the opossum’s primary habitat is forested areas, it can also be found in open areas and has adapted very well to the urban environments man has created. These mammals have expanded their range into climates that were once too harsh most likely due to the activities of man. They are active primarily at night where they cover 1.6-2.4 km and have a home range of about 20 ha. Opossums are nomadic and remain in any area for only a few months. They have a diet that consists of what ever is available including vertebrates, invertebrates as well as vegetable matter.
The Virginia Opossum (Didelphis virginiana) has a remarkable resistance to the venom of the Western Diamondback Rattlesnake (Crotalus atrox) (McKeller et al., 2001). This resistance comes from their ability to neutralize the venom with antihemorrhagic response as apposed to an antibody response. In fact, there was not even evidence that the Opossum can produce antibodies in response to the venom. The estimated ability of the opossum to neutralize venom is over 140 times greater than ordinary mammals.
The African Honey Badger is another generalist carnivore that has the ability to prey on venomous snakes. Although no study has been done with them to assess their level of resistance, they do show a surprising ability to metabolize venom. In the Mustelidae family, the Honey Badger (Mellivora capensis) lives in areas along side some of the deadliest snakes on the planet. It occupies a range of habitats across the African continent and well into Asia. It has a diet of nearly anything and is a great digger to unearth located prey. It has been extensively trapped and poisoned due to its destructive nature to livestock such as chickens. (Nowak, 1999. pp. 727-728)
All of these example mammals have specific adaptations that allow them to prey on dangerous and often deadly organisms. Their foraging behavior of each could be described as fearless.

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