Tuesday, August 7, 2007 - 2:30 PM

COS 58-4: On the role of phylogenetic analyses for non-heritable traits

William E. Kunin, University of Leeds

Phylogenetically informed methods have become widely accepted in comparative analyses involving heritable species traits.� These techniques correct for spuriously high levels of association between such traits due to shared inheritance.� Recently, techniques have been developed to allow analyses of pairs of traits only one of which shows phylogenetic patterning, by making use of simultaneously diverging �star-shaped� phylogenies.� In this talk, I will show that such approaches are unnecessary, and thus needlessly reduce statistical power.� Using simulated phylogenies, I will show that no inflation of significance occurs in pairwise analyses where one trait shows no phylogenetic pattern, however strong the pattern of inheritance in the other trait.� I will also discuss the more difficult issue of whether phylogenetically informed analyses are needed where traits are intrinsically not heritable, such as analyses of species distribution or abundance.� In such cases, any apparent phylogenetic pattern in the non-heritable trait must reflect the influence of heritable traits, and thus should be part of the �signal� rather than the �noise�.� In such cases, the prudent course may be to perform standard non-phylogenetic analyses, but to examine residuals for phylogenetic pattern, as a means of detecting the influence of heritable factors not included in the analysis.