Abstract
Majority-rule consensus and bootstrap bias; global lability and regional resolution
Abstracts with programs - Geological Society of America, Vol.31(7), p.138
Geological Society of America, 1999 annual meeting
1999
Abstract
Taxon lability -- the ways in which an ingroup taxon assumes different sets of relationships in different optimal phylogenetic trees -- is a major problem faced by researchers during phylogenetic reconstruction. A regionally labile taxon switches positions among a few derived branches at the crown of one lineage, causing a collapse of resolution in the strict consensus tree within that clade, but no general influence on the rest of the tree. At the other extreme, a globally labile taxon (rogue taxon) assumes sister-taxon relationships with most, or even all, ingroup taxa. Rogue taxa can sharply reduce resolution in a strict consensus of optimal trees in a phylogenetic analysis, even if the underlying data set preserves a strong hierarchical signal. Although majority-rule consensus trees can recover some of this signal, its expression can be strongly biased if the rogue taxon's placement is consistent with widely separated islands of parsimony of different sizes. This situation biases the majority-rule consensus toward the least resolved of the alternative islands of parsimony simply because it is consistent with more of the optimal trees than with the more-resolved alternatives, which would not be acknowledged. This raises questions about the utility of majority-rule consensus for expressing the results of a phylogenetic analysis. More generally, the results of a bootstrap analysis -- the most predominant method for assessing nodal robustness -- are typically presented as a majority rule consensus tree, and may thus also be biased toward less-resolved islands in the presence of a rogue taxon. This is shown through both real data sets as well as simulation studies, which show that the situations causing rogue taxa -- large amounts of missing information in a data set, coupled with heterogeneous distribution of incompleteness among ingroup taxa -- are particularly common in paleontological data.
Details
- Title: Subtitle
- Majority-rule consensus and bootstrap bias; global lability and regional resolution
- Creators
- Christopher A Brochu - Field Museum of Natural HistoryColin D Sumrall - Geier College USA United StatesJohn W Merck - University of Texas at Austin USA United States
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.31(7), p.138
- Conference
- Geological Society of America, 1999 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 1999 annual meeting
- Language
- English
- Date published
- 1999
- Academic Unit
- Earth and Environmental Sciences; University College Courses
- Record Identifier
- 9984240908902771
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