[adegenet-forum] interpretation of DAPC axes

[Pfau, Dr. Russell S.]

I'm a little uncertain how to interpret the axes of the scatterplot of the DAPC.  I know how to interpret the axes of a PCA or PcOA.  For example, Fig 8 of your BMC Genetics paper shows a U-shaped pattern...which is also seen in Fig 4 c and d.  Is this the 'arch effect' or 'horseshoe effect'?  Is this a problem?  How is it interpreted?    

I've just run a DAPC of one of my datasets (with 24 populations) and the DAPC scatterplot shows populations arranged in a *prefect* circle...a donut shape.  How would one interpret that?  A PcoA and STRUCTURE analysis of the same data who hierarchical clustering (two divergent populations, one having subpopulations with introgression occurring among the subpopulations).  The donut makes me think this is a ring species which I know it is not.

Thanks!!
Russell