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natural selection

natural selection - Speciation in the Canidae Family...

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Speciation in the Canidae Family
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Learning Objectives Define phylogenetic systematics and describe what type of data are used to build phylogenetic trees. Read and make inferences about evolutionary relationships from a phylogenetic tree. Explain how morphological and molecular characteristics are used to construct phylogenetic trees. Build phylogenetic trees based on molecular and/or morphological data. Explain the process of natural selection, including the roles of phenotypic variation, genetics, and fitness. Explain the concept of genetic drift, including the “founder effect” and “genetic bottlenecks.” Explain artificial selection and pedomorphosis. Use the example of canine evolution to describe natural selection and artificial selection. Given information about other phyla that are new to you, decide if selection or drift likely accounts for evolution of those phyla and explain why. Use data to answer phylogenetic questions. 2
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A young boy is sitting near the edge of a cave 50,000 years ago. He has just taken out the garbage from the previous day’s activities, mostly bones and waste from a recent hunt. As dusk approaches, the wolves start to arrive. 3
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The boy is not frightened. He has seen the wolves many times before. He notices that the same wolf is always the first to get the good scraps. It doesn’t immediately run off when it sees the boy like the other wolves do. Domestic dogs wouldn’t appear on the scene for another 10,000-35,000 years. 4
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Domestic dogs look like they are more closely related to wolves than to other canids Siberian husky (domestic dog) Gray wolf 5 Maned wolf
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Of course, looks can be deceiving! Lhasa apso (domestic dog) Phylogenetic analyses are more convincing. Gray wolf 6
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Phylogenetic Analysis Phylogenies can be based on morphology Similarity of many morphological characteristics are used (color, size, structure, etc.) Most recent phylogenies are based on molecular similarities E.g., similarities of mitochondrial DNA (mtDNA) sequences 7
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Phylogenetic Systematics The study of evolutionary relationships A phylogenetic tree (Think of it as a family tree) A B C D Recent time Past time Node 8
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Reptile Phylogenetic Tree Recent time Past time Node indicating ancestor of crocodiles and birds Node indicating ancestor of turtles, lizards/snakes, crocodiles, and birds Crocodiles and birds are more closely related than turtles and birds because they share a more recent common ancestor. Birds did not evolve from crocodiles. They share a recent common ancestor with crocodiles. 9
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Which statement can you infer to be true based on this phylogenetic tree? A. Species A, B, and C are extinct B. Species C & D shared a common ancestor more recently than B & D C. Species D will display the most advanced morphological characteristics D. Species B is most closely related to species A A. Species D evolved from Species C A B C D 10 Clicker Question  1
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Proposed Canid Phylogeny Swift fox Maned Wolf Gray wolf Coyote Red fox South American foxes Jackal African Wild Dog Domestic Dog 11
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