Biology Chapter 25 Objectives

Biology Chapter 25 Objectives - Chapter 25 Phylogeny and...

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Chapter 25 Phylogeny and Systematics Phylogenies are Based on Common Ancestries 1. Phylogeny is the evolutionary history of a species or group of species. Systematics is an analytical approach to understanding the diversity and relationships of organisms, both present-day and extinct. 2. In order for sedimentation and the formation of fossils to occur, rivers first carry sediment to the ocean. Sedimentary rock layers containing fossils form on the ocean floor. Over time, new strata are deposited, containing fossils from each time period. As sea levels change and the seafloor is pushed upward, sedimentary rocks are exposed. Erosion reveals strata and fossils. Hard shells, skeletons, or other hard parts are most likely to fossilize. 3. It is crucial to distinguish between homology and analogy before selecting characters to use in the reconstruction of phylogeny. This is because an adaptation might be a superficial resemblance that implies a close relationship to one organism, but upon closer examination, it is revealed that the complex adaptive structure is more similar to another organism. 4. Bird and bat wings are homologous as vertebrate forelimbs but analogous as wings. Fossil evidence documents that bat forelimbs and bird wings arose independently from walking forelimbs of different ancestors. Thus, the bat’s forelimb is analogous in function to a bird’s wing. 5.
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Biology Chapter 25 Objectives - Chapter 25 Phylogeny and...

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