How do you read Evolutionary Trees?
Channel: YouTooBio
Date: 2020-09-21

Did a doctor spitefully infect his ex-girlfriend with HIV? This video describes the first time an Evolutionary Tree* was used in a criminal court in America. Learn how to interpret the relatedness of organisms on any Evolutionary Tree... and find out whether the doctor actually did it.
*Also sometimes called a Phylogenetic Tree.

0:00 Introduction
0:29 Example of using evolutionary tree in court case
1:14 Trees depict organismal relationships 
2:29 How to read evolutionary trees
3:17 Count the steps?
4:00 See which organisms are closest to each other?
5:20 Compare the Most Recent Common Ancestors?
6:37 Example of using evolutionary tree in court case conclusions 

The paper behind this video:
M. L. Metzker, et al., Molecular evidence of HIV-1 transmission in a criminal case. Proceedings of the National Academy of Sciences 99, 14292–14297 (2002). http://doi.org/10.1073/pnas.222522599

Scientific Consulting by Cynthia Darnell
Cartoon Illustrations by Michelle Lotker

Images:
Elephant by Muhammad Mahdi Karim GFDL 1.2
Lion by Rufus46 CC BY-SA 3.0
Eagle by Vtornet CC BY-SA 3.0
Squid by Hans Hillewaert CC BY-SA 4.0
HIV micrograph by CDC/Dr. Edwin P. Ewing, Jr. / Public domain
T rex by Zissoudisctrucker CC BY-SA 4.0
Tiger by Lotse CC BY-SA 3.0
Polar Bear by Alan Wilson CC BY-SA 3.0
Grizzly Bear by Dwayne Reilander CC BY-SA 4.0
Flamingo by Charles J Sharp CC BY-SA 3.0
Snail by CJ Samson / Public domain
SARS-CoV-2 by NIAID-RML CC BY-SA 2.0

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