The formation of new species is often an extended process which can proceed to varying degrees. Dr. Nosil discuss how speciation might proceed further either by natural selection acting: (1) more strongly on one or a few key traits/genes (a ”˜stronger selection’ hypothesis) or (2) on a greater number of independent traits/genes (a ”˜multifarious selection’ hypothesis). He will begin with phenotypic tests of these ideas in herbivorous walking-stick insects, then turn to both theoretical and empirical results exploring these hypotheses at the genomic level. The collective results provide some support for each hypothesis, but also indicate that the efficacy of multifarious selection acting on many gene regions in driving speciation might be underestimated.