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Abstract Detail


Systematics Section / ASPT

Pfeil, Bernard E. [1].

Incongruence caused by hybridisation, lineage sorting or paralogy biases molecular dates inferred by combined analyses.

Events that shape genomes can uncouple gene phylogenies from species phylogenies. Combined analysis of sequence data from multiple loci (character congruence) has been advocated by various authors as the best approach to address phylogenetic questions. However, I show that the addition of incongruent data matrices introduces biases in molecular date estimates with standard date estimation procedures (e.g., Bayesian tree building followed by r8s). These biases are predictable in direction and more often increase the estimated ages of nodes, but sometimes decrease them. The effect of the bias is on the branch lengths, so all dating procedures are likely to be affected. The bias arises because more than one event is being pointed to by the gene trees (e.g., time of speciation or time of deep coalescence), but the combined analysis using tree building methods forces character conflict to be accounted for as homoplasy on a tree rather than as potentially different solutions. Prospects for improving date estimations with these types of incongruence will be discussed.


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1 - CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia

Keywords:
molecular dating
incongruence
character congruence
combined analysis
separate analysis
total evidence.

Presentation Type: Oral Paper:Papers for Sections
Session: CP24
Location: Continental C/Hilton
Date: Tuesday, July 10th, 2007
Time: 12:00 PM
Number: CP24015
Abstract ID:1105


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