PPT Slide

Tree of Life

Problem: how to build the tree of life

Tree terminology

Nestings and triplets

Supertree

Some desirable properties of a supertree method(Steel et al., 2000)

Aho et al.ís algorithm (OneTree)

Mincut supertrees

Collapsing the graph(Semple and Steel mincut algorithm)

Cut the graph to get supertree

My mincut supertree implementationdarwin.zoology.gla.ac.uk/~rpage/supertree

A counter example: two input trees...

Mincut gives this (strange) result

Problem:Cuts depend on connectivity(in this example it is a function of tree size)

So, mincut doesnít work

What mincut doesÖ Öand does not do

Modifying mincut supertree

Uncontradicted informationassume we have k input trees

Classifying edges

Modified mincut

If no tree contradicts an item of information, is that information always in the supertree?

No!Steel, Dress, & B–cker 2000

Future directions

Email: r.page@bio.gla.ac.uk

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