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e Trees Cloud Even Recent Past Tracking the Evolutionary History

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e Trees Cloud Even Recent Past Tracking the Evolutionary History

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Title	e Trees Cloud Even Recent Past Tracking the Evolutionary History
Contact	mailto:nctcimages@fws.gov
Producer	USFWS/NCTC
Description	Conservation Science Webinar Series - Presented by Dr. Steve Fain, Research Coordinator for the Genetics Section at the USFWS National Forensics Laboratory. September 19, 2012. A scan of recent titles from the molecular systematics literature finds the species tree of bears to be a classic “cloud of gene histories” punctuated by rapid events of divergence. As a result, the phylogeny of bears has been complicated by cross species hybridization and the incomplete sorting of ancestral polymorphism. It should come as no surprise then that the topology of the phylogenetic species tree of brown bears and polar bears is not always in agreement with estimations drawn from individual gene trees – most prominently those based on mitochondrial DNA (mtDNA). Our results from nuclear DNA (nDNA) sequence comparisons of polar bears, brown bears and black bears disprove the viewpoint from phylogenetic assessments of mtDNA that polar bear and brown bear diverged just 160,000 years ago. Calibrations of our data with nDNA divergences between polar bear–panda and polar bear–spectacled bear indicate that polar bears and brown bears separated more than 0.6 million years ago. Polar bears are an ancient sister lineage to brown bears and, as a consequence, have lived through several previous warm interglacial phases. Threats to their survival unique to this current phase will also be discussed.
Subject	videography webinar conservation science
Publisher	U.S. Fish and Wildlife Service
Contributors	USFWS/NCTC
Date Published	2012-09-20
Type	Video
Format	H264
Item ID	1851843972001
Source	NCTC Image Library
Language	English
Rights	Public Domain
Audience	General
Original Format	Digital
Length	00:59:16
Collection	Conservation Science; Webinar
Presenter	Presented by Dr. Steve Fain, Research Coordinator for the Genetics Section at the USFWS National Forensics Laboratory.
Video Player Link	https://fws.rev.vbrick.com/#/videos/13354650-303d-4555-a6c4-670bf4c2023f
Archival file	Volume18/2274.url
Date created	2013-02-22
Date modified	2017-12-19