Damien Esquerre asked: > What do you think would be the most appropriate way to deal with this > situation then, if you are interested in environmental effects on shape?
Issues of heterogeneity of regression parameters are relevant, but there is one more issue that also needs attention. That is, that individual species should not be treated as independent, identically distributed. One needs to integrate such an analysis into a phylogenetic comparative method. Doing a regression across species to remove a size effect is incorrect unless done taking the phylogeny into account. In addition, one should not assume that an environmental effect has all of its influence in the most recent generations. Ideally, we would also want to allow for the environment of the past to have had effects on the species, effects that have partially persisted until today. That raises the uncomfortable issue of how one models the change of the environment along the tree. We could have it too change by Brownian Motion, but this seems arbitrary when applied to some aspect of the physical environment, such as mean annual temperature. It's clearly a difficult problem. J.F. ---- Joe Felsenstein [email protected] Department of Genome Sciences and Department of Biology, University of Washington, Box 355065, Seattle, WA 98195-5065 USA -- You received this message because you are subscribed to the Google Groups "Morphmet" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/morphmet2/CABXfcPFLT5p4q59Su-Ag3p4G8EGSSJozKQxr6pv%2BE8gD0bLrSA%40mail.gmail.com.
