Extinction and Evolution
Ecology helps us understand the importance of mass extinction in evolution, and it also helps us understand some of the causes of extinction. Ecological niche is one of the most important concepts to understand. An animal or plant lives in a certain place is active at a particular times, and eats certain things; all these factors describe its ecological niche.
Our environment is parted into millions of ecological niches, each that represents a probable home for life. Taking advantage of new opportunities are what animals and plants will always try to do, so they will always try to make a home in an empty niche. To specify, only one animal or plant can have a certain niche. When two different organisms try to take the same niche they will compete for the same resources, and one will always try to out-compete the other. When the species is extinct and there is an empty niche, there will be a race to fill it. Mass extinctions open up a swarm of niches, and there is evolutionary explosion as animals and plants adapt to fill the vacant homes.
As we all know the environment of the Earth is always changing which might have led to some niches being destroyed, making the species that have took it to extinction. A fall of sea level might lead to loss of shallow seas, so the species that made the niche in shallow seas home might become extinct, or evolve into forms adapted to the new environment. On the other hand, if two continents crash to form one, larger continent, then the niches of two continents can merge, no longer separated by a barrier. This leads to competition between the two species for the same niche, and can cause the extinction of one.
The dinosaurs did not survive on Earth. How is it that mammals and many birds did? Of course millions of species and thousands of types lower in the phylogenetic tree survived as well even though millions more went extinct. The basic rule of evolution is that the fittest organisms (species)...
Bibliography: * http://www.talkorigins.org/faqs/faq-intro-to-biology.html
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