Biology 1002B Lecture 19: Lecture 19-notes
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Extinction is part of the process of evolution. Species and lineages have been going extinct since life first appeared. We should expect species to disappear at some low rate, the background extinction rate; as environments change, poorly adapted organisms do not survive and reproduce . The fossil record indicates that extinction rates rose well above the ground rate at least five times in. These events are referred to as mass extinctions. The disappearance of the dinosaurs is one of the best-known extinction events in earth history. Rabies affects the nervous system of terrestrial mammals. Rabies is usually spread by bites because the virus accumulates in the saliva of infected animals. Paralysis of the throat muscles means that rabid animals cannot swallow the saliva they produce , so they appear to foam at the mouth. Three phases-(a) developing an oral vaccine; (b)developing a means of vaccinating foxes; and (c) monitoring the impact of the program on the fox population.