BIOL 1070 Lecture Notes - Lecture 23: Permafrost, Ecological Niche, Paraphyly
5 Apr 2016
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Document Summary
Polar bear is not monophyleic because the tree represents a tree of one species with sub populaions (i. e. , polar bears are actually brown bears), therefore the lineage includes all of the ancestors of all of the brown bears. Dna analysis has conirmed that brown and polar bears have inter-bred in the wild. Nuclear dna and mitochondrial dna analysis tell us diferent stories. Nuclear dna is paternal (in sperm, which has a nucleus) whereas mitochondrial. Dna is maternal-this is important to think about when analyzing the data. Brown bears are slowly convering polar bears into brown bears as they are moving into the polar bear range and inter-breeding with them. Polar bears may re-evolve if the condiions are correct; if they go exinct and come back it will be a whole new species. Polar bears are specialized carnivores, brown bears are generalist omnivores. Polar bears and brown bears can produce ferile hybrid ofspring.
