BIOL 1911 Chapter Notes - Chapter 25.6: Macroevolution, Microevolution, Hyracotherium
24 Mar 2018
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Document Summary
The origin of new species has been affected by both small-scale factors, such as natural selection, as well as large-scale factors such as continental drift. Evolution is like tinkering a process in which new forms arise by the modification of existing structures or existing developmental genes. Evolution has led to the three key features of the natural world: the striking way in which organisms are suited for life in their environments, the many shared characteristics of life, the rich diversity of life. Tinkering alike to darwin"s concept of descent with modification. As new species form, novel and complex structures can arise as gradual modifications of ancestral structures. Exaptations structures that evolve in one context but become co-opted for another function. Some evolutionary lineages exhibit a trend toward larger or smaller body size: ex: evolution of the present-day horse. Extracting a single evolutionary progression from the fossil record can be misleading.
