search for: dimorphism

Hello! I am working on a manuscript on sexual dimorphism in an aquatic invertebrate, where we have estimated sexual dimorphism (SD) for 7 different traits in four populations (a total of 28 SD-estimates). We have used the following formula for estimating SD: 100 * (mean male trait value - mean female trait value)/overall trait mean). Then, we have used...

...have smaller horns and larger wings, and rely on mobility to find mates before the guys with the big horns turn up and beat them up. Normally what we do to see if this is happening is to plot a scatter plot of horn length vs body size. If it's a simple straight line relationship then no dimorphism, but if it's either a line with an obvious change of slope or two separate lines then you've got a dimorphic animal. If you've just got a change of slope then it's relatively easy to test for significance by breakpoint regression, which will also tell you the body size at w...

Dear all, Does anyone know if the mixture analysis (i.e : sexual dimorphism, age group,…) can be done with R software ? Thanks for your help Dan --------------------------------- [[alternative HTML version deleted]]

I'm trying to perform ANCOVAs in R 1.14, on a Mac OS X, but I can't figure out what I am doing wrong. Essentially, I'm testing whether a number of quantitative dental measurements (the response variables in each ANCOVA) show sexual dimorphism (the sexes are the groups) independently of the animal's size (the concomitant variable). I have attached a 13-column matrix as a data frame (so far, so good). But then I tried to do this: >model<-lm(ln2~sex*ln1) or this: >model<-lm(ln2~sex+ln1) and got this: Warning message:...

...neralized non-linear least squares function within the nlme library, to study evolutionary questions where correlations between traits at the species level are non-independent because of the evolutionary relatedness of the species. Specifically, they're using a non-linear function (log(sexual dimorphism) ~ log(a + b*variation in mating opportunities), an exponential spatial correlation function that depends on the phylogenetic distance between species [I hacked the library a little bit to allow one to specify a distance matrix directly, rather than specifying spatial positions], and a weight fun...