comparative method
Stone GN, Nee S & Felsenstein J 2011 Controlling for non-independence in comparative analysis of patterns across populations within species. Phil Trans R Soc B 366:1410-1424.
- the phylogeny-based approaches widely used in cross-species analyses are unlikely to be useful in analyses across populations within species
- community genetics examines the impact of genetic diversity in one species on associated community structure and ecosystem processes
- one common question concerns the extent to which individual or population genetic diversity in keystone species predicts associated community species richness and abundance
- if the working phylogeny is inaccurate, the performance of PIC methods deteriorates significantly
- this is the major argument against applying this approach to within-species analyses
- population-splitting events can be very hard to reconstruct with any confidence
- within species, phylogeny-based methods are only likely to be appropriate where populations are resolvable as independently evolving lineages
- more work is needed on the impacts of alternative population models (and hence variance-covariance structures) in intraspecific comparative analysis
- examples include the metapopulation models that have received considerable attention in a coalescent framework
- x(t + 1) = σp + (1 − σ)Mx(t) + e
- M = C−1ΛC
- y = Cx
- x = σp + (1 − σ)Mx
- x = σp + (1 − σ)C−1ΛCx
- Cx = Cσp + (1 − σ)ΛCx or y = Cσp + (1 − σ)Λy
- 'contrasts' are simply data that have been transformed in such a way that the effects of entangling factors have been removed
