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Animation: Overview of Macroevolution

by Pearson
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Microevolution by itself does not explain the diversity of life on Earth today. Let's investigate the role that macroevolution plays in this process. Let's begin with the evolution of each species to understand macroevolution. Multiplication of species creates biological diversity with the evolution of many different species from one common ancestor. This can be seen with Darwin's finches on the Galapagos Islands. Sometimes referred to as branching evolution, or adaptive radiation, this occurs when multiple habitats and niches open up with relatively little competition. Note how evolutionary novelty results from the gradual refinement of existing structures for new functions. Here, we see how ancestral birds may have used wing-like forelimbs for courtship. They could also have taken advantage of these enlarged forelimbs to allow for extended hops and gliding ability. Once flight itself became an advantage, natural selection would have remodeled feathers and wings to better fit their additional function. Let's review what happens when a mass extinction takes place. After a mass extinction, previously filled niches and habitats are opened up. For example, when the dinosaurs became extinct, mammals had the opportunity to evolve into those niches and produce incredible diversification. Explosive diversification often occurs following the evolution of an important adaptation. For instance, the evolution of the flower from early seed plants, which were similar to modern conifers, allowed plants to reproduce more efficiently and thus exploit many previously unavailable habitats and niches.
Microevolution by itself does not explain the diversity of life on Earth today. Let's investigate the role that macroevolution plays in this process. Let's begin with the evolution of each species to understand macroevolution. Multiplication of species creates biological diversity with the evolution of many different species from one common ancestor. This can be seen with Darwin's finches on the Galapagos Islands. Sometimes referred to as branching evolution, or adaptive radiation, this occurs when multiple habitats and niches open up with relatively little competition. Note how evolutionary novelty results from the gradual refinement of existing structures for new functions. Here, we see how ancestral birds may have used wing-like forelimbs for courtship. They could also have taken advantage of these enlarged forelimbs to allow for extended hops and gliding ability. Once flight itself became an advantage, natural selection would have remodeled feathers and wings to better fit their additional function. Let's review what happens when a mass extinction takes place. After a mass extinction, previously filled niches and habitats are opened up. For example, when the dinosaurs became extinct, mammals had the opportunity to evolve into those niches and produce incredible diversification. Explosive diversification often occurs following the evolution of an important adaptation. For instance, the evolution of the flower from early seed plants, which were similar to modern conifers, allowed plants to reproduce more efficiently and thus exploit many previously unavailable habitats and niches.