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Macroevolution - Mating rituals/songs Sterile offspring...

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2/9/11 1 Chapter 18 Macroevolution Sections 18.1-18.4 only How many species? Unknown! 3 million? 100 million? Many unexplored areas of planet (Depends on definition) Species A group of actually or potentially interbreeding natural populations that are reproductively isolated from other such populations Natural Populations Exist in the wild; interbreeding in captivity doesn’t count for species definition (example: ligers and tigons) Speciation Creation of new species Occurs when populations stop interbreeding Geographic isolation is often the beginning
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2/9/11 2 Geographic Isolation Two populations are separated geographically and don’t interact Examples: islands, mountain ranges, Grand Canyon Reproductive Isolation For speciation to occur, populations must change genetically so they can no longer interbreed Examples: seasonal or time of day
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Unformatted text preview: Mating rituals/songs Sterile offspring Example of sterile offspring A mule is the offspring of a horse and a donkey Mules are strong, valuable animals but they have 63 chromosomes and can’t reproduce Adaptive radiation The rapid evolution of many species from a single species that has been introduced to a new environment Seen most easily on islands, but happens all over In the Hawaiian islands, one kind of drosopholid fly became 500 species 2/9/11 3 Scientific Names Two parts, Latin Genus species Examples: Canis domesticus & Canis lupus Felis domestica & Felis silvestris Tree of Life online site: tolweb.org Phylogenetic tree Branches are new species Branching points are on a time scale Closer branch points = more closely related...
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