What you describe – samples from multiple populations – is best considered as a random effect in a typical generalized linear model format. You have randomly sampled some populations from all of those that might be available. If I understand your data correctly, to evaluate allometry, use a mixed model approach where some trait measurement is the response variable and some measure of body size would be the predictor variable, then population would be included as a random effect in the model. This structure has the advantage of accounting for and adjusting for covariation among populations before the fixed effect is evaluated. Appropriately crafted mixed models can rigorously account for a range of complicated covariance structures within the context of one model. Several examples of the use of mixed models in ecology and evolution can be found in the literature. Hope that helps,
Mark Mark C. Belk, Professor of Biology Brigham Young University Editor, Western North American Naturalist 801-422-4154 From: Ariadne Schulz [mailto:[email protected]] Sent: Wednesday, January 18, 2017 1:27 PM To: Elahe Cc: MORPHMET Subject: Re: [MORPHMET] eliminating the effect of population differences I would like to hear any responses to this as well. I did something similar and I wasn't sure how to approach this question. In future studies I would like to address precisely this issue. My inclination would be that first you would want to determine how much morphological variation you're getting between sites. You could then look at sexual dimorphism within each site and/or you could look at variation of only females and only males over all sites. But this is all rather clunky and does not eliminate any interpopulation variation. If anyone has already proposed or can propose a better methodology I'd be interested in it as well. Best, Ari On Wed, Jan 18, 2017 at 5:29 PM, Elahe <[email protected]<mailto:[email protected]>> wrote: Dear all, I have pooled samples from 7 different populations of one species in order to study the allometric growth and sexual dimorphism in that species. As different populations may have subtle differences in terms of body dimensions with each other, I want to remove their effects. Can anyone suggest a way to eliminate population effects and maybe finding some residuals that are homogeneous and can be used for further analyses? I would appreciate any helps :) -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org --- 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]<mailto:[email protected]>. -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org --- 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]<mailto:[email protected]>. -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org --- 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].
