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THE RECONSTRUCTION OF ANCESTRAL CHARACTER STATES
Author(s) -
Schultz Ted R.,
Cocroft Reginald B.,
Churchill Gary A.
Publication year - 1996
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1996.tb03863.x
Subject(s) - biology , character (mathematics) , inference , clade , character evolution , phylogenetic tree , phylogenetics , evolutionary biology , skew , rate of evolution , range (aeronautics) , state (computer science) , genetics , algorithm , mathematics , computer science , artificial intelligence , gene , telecommunications , geometry , materials science , composite material
The problem of error in the phylogenetic reconstruction of ancestral character states is explored by developing the model of Frumhoff and Reeve (1994). Information about the evolutionary rate of change within a character is inferred from the distribution of its character states on a known phylogeny, and this information is used to impose confidence limits on the error associated with ancestral state inference. Ancestral state inference is found to be remarkably robust under the model assumptions for a wide range of parameter values; however, the probability of error increases when the number of species within a clade is small and/or state‐transition probabilities are strongly skewed in favor of the non‐ancestral state. The rationale for expecting such a skew, a hypothesis of parallelism, is shown to rely on assumptions of low rates of change in at least two phylogenetically inherited characters: the tendency to occupy a particular ecological niche and the tendency to respond in a particular way to selection. A means for judging the relative likelihoods of parallelism vs. straightforward homology as explanations for a given character‐state distribution is suggested. General problems with the model are discussed, as are methods for making it more realistic.