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Chapter 1

Evolution Textbook notes-chapter 1.docx

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BIOL 2400
Cortland Griswold

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Evolution Textbook notes: Chapter 1: Biological Evolution: Any change in the inherited traits of a population that occurs from one generation to the next. - Evolution is a process by which populations of organisms change over time. - Whales and dolphins are known as Cetaceans.  They develop in the uterus, forming a placenta  Born alive and drink milk  Descended from mammals that lived on land Lineage: A chain of ancestors and their descendents. Natural Selection: A mechanism that can lead to evolution, where differential survival and reproduction of individuals causes some genetic types to replace (outcompete) others. Convergent Evolution: The independent origin of similar traits in separate lineages. Homologous: Characteristics are similar in two or more species because they are inherited from a common ancestor. Synapomorphy: Derived form of a trait that is shared by a group of related species (ex: one that evolved in the immediate common ancestor of the group ans was inherited by all its descendants) - The mammalian middle ear is an air-filled cavity enclosed in a hollow shell known as the Ectotympanic. - The inner wall of the ectotympanic is the Involucrum. - Eocene period, was from 56 to 34 million years ago. - Pakicetus is the fossil found in Pakistan; meaning " whale of Pakistan" , and was 50 million years old. - Ambulocetus meaning "walking whale". - Darwin argued that life evolved like a branching tree with new lineages splitting off from old ones. Phylogeny: A visual representation of the evolutionary history of populations, genes, or species. - Scientists can get clues about the origin of cetaceans also from looking at the individual atoms inside the animal. (ex. could tell if they drank fresh or salt water) - Mutations had developed which put a stop to the growth of the limb buds in cetaceans. - Scientists have concluded that whales had lost their teeth and had developed pleats instead; much like how they lost their limbs. - Whales were hunted for their oil and baleen (oil for lamps and baleen for corset strays) - Whale and fish lineages, evolving independently, converged on body forms that are superficially similar. - Ambulocetus was a fossil whale that had legs. The animal had traits that were intermediate btwn modern whales and their terrestrial ancestors. - The chemistry of fos
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