[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Long branch attraction



Well, Mr. Marjanovic,

Explained it very well. But if you were interested in a more deep
explanation (though from a biomolecular point of view):

A review of long-branch attraction
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1096-0031.2005.00059.x

[]s,

Roberto Takata

On 8/14/06, Phillip Bigelow <bigelowp@juno.com> wrote:

Roberto Takata <rmtakata@gmail.com> writes: > As longer a branch is, more mutations are inferred to occurred in the > lineage.


So, if there are only 2 steps between the two basal-most taxa on a branch, but there are 15 steps between them and the next taxa "higher up" on the branch, would that be an example of a "long branch"? And should this topology be held suspect?


> > More mutation there are, more probable that homoplasies arise. > Since > we assume maximum parcimony, homoplasies are prone to be taken as > homologies...


So, the problem with having many steps between taxa is that it increases the risk of the computer algorithm misinterpreting homoplasies as homologies. Therefore, distantly-related taxa get "attracted" to one evolutionary branch, when they actually should be on put on different branches.

How'm I doin'?

<pb>
--
"If you are traveling into the future in a time machine, and you pass a
person from the future who is traveling into the past, it's probably a
good idea to avoid eye contact." - Jack Handey