Recent research has shown another characteristic that can help identify herbivores from omnivores and carnivores. Vertebrates have taste receptors called "Tas2r" that receive the taste of bitter plants. This receptors aids in the avoidance of poisonous plants. The recent research showed that herbivores have many more of these Tas2r receptors than the other two diet groups. Using evolution trees and genetic information from over 50 vertebrates, it was concluded that the high number of bitter receptors has evolved in herbivores over time most likely as a protection mechanism. Since the other diet groups do not reply heavily on plant matter for food, this ability did not need to evolve. Since plants are so highly evolved and varied, it is more likely for a predator to be poisoned by a plant than by another animal. The Tas2r receptor count correlated so well with the diets of the animals that the number of these receptors can now be used to help categorize animals.
It is easy to see why it would be beneficial to herbivore species to evolve a stronger detection for poison since they are more likely to come across poison than other species. Depending on their environment, a plant eating animal could come in contact with hundreds or thousands of plant species in their life and it is extremely important to their survival to know which they can and can't eat. Non-herbivore animals do not have to deal with as much diversity and can quickly learn what insect are dangerous etc...
Source: http://www.sciencedaily.com/releases/2013/11/131118160043.htm
It makes sense that herbivores would have more Tas2r taste receptors. Considering their diets are based on plants, these receptors would help the stronger survive over time.
ReplyDeleteI agree with Deb that it makes sense for herbivores to have more Tas2r receptors since some plants the animals might eat could be bitter. Since carnivores don't eat plants it makes sense they don't have many if at all. I found it fascinating that they can detect poison because of these receptors.
ReplyDeleteI wonder what the receptor count is for humans relative to herbavors? Even though we're considered omnivores, many cultures in rural areas may still gather much of their food. any correlative findings between rural and urban and their receptor count would definitely be of interest
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