bio masterbiol - Estimated time: 7:41 Vocabulary:...

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Estimated time: 7:41 Vocabulary : speciation Hey there. This is Eric Simon and welcome to another MP3 Tutor session. Let’s jump right in to today’s topic— speciation . In the arid plains of southeast Colorado, a small river has carved an isolated canyon known as Picketwire. Far back in the canyon, erosion by the river has exposed a narrow shelf of rock about a quarter mile long. Getting there is difficult, but those that make the journey are not just traveling to a remote and beautiful area. They are also making a journey back in time. You see, the shelf of rock exposed by the river was once the muddy shores of a lake. Recorded on those once-muddy shores are hundreds of dinosaur tracks. In Picketwire you have a window into Earth’s history, a history dominated by organisms that are now extinct. Colorado is a state rich in fossil deposits like Picketwire that provide us with clues and evidence about Earth’s history. Written in fossils, the story of life is a recurring story of extinction events in which large numbers of organisms disappeared from the fossil record followed by the appearance of new forms of organisms. How do new species arise? This is called macroevolution—the evolution of species. Charles Darwin’s theory of natural selection provided the framework of an answer to that question. But can the small changes from generation to generation, typical of evolution by natural selection, account for the large differences that we see between species or between groups of species? The short answer is yes and in this MP3 tutorial we will explore how speciation occurs. Let’s begin with a difficult task: defining just what a species is. Biologists have struggled with this for
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This note was uploaded on 04/05/2012 for the course BIO 102 taught by Professor Larson during the Spring '12 term at Jefferson College.

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bio masterbiol - Estimated time: 7:41 Vocabulary:...

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