Monday, November 16, 2009

Bio question?

Your teacher wants you to construct a phylogenetic tree of orchids. He gives you tissue from seven orchid species and one lily. What is the most likely reason he gave you the lily?





A) to serve as an outgroup


B) to see if it%26#039;s a cryptic orchid species


C) to see if the lily and the orchids show all the same shared derived characters (synapomorphies)


D) see if you were paying attention

Bio question?
A, outgroup





Outgroups are often used in creating phylogenetic trees, because you can compare each of the species you%26#039;re trying to map to that one odd species - in this case, the lily. Seeing how many differences each orchid has with the lily helps you realize how closely related the orchid species are.
Reply:A.
Reply:What do you think? That%26#039;s pretty amusing, though - you%26#039;ve got a good teacher!


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