Species concepts, speciation, and sexual selection

The debate over species concepts is ongoing and intense. I believe that a concept that places primary emphasis on correct representation of history will replace the biological species concept. The notion that species are special entities of nature independent of the work of taxonomists is perhaps one reason why the debate is so intense. I agree with Nelson (1989) in thinking that species are no different from any other taxonomic category, at least in terms of being units of history. The BSC has motivated generations of students interested in geographic variation and speciation (Futuyma 1987), largely because it has been believed that speciation processes could be discovered. I think that the success of the BSC in clarifying speciation has been largely illusory. Study of pattern and process has been confused under the BSC, and, therefore, speciation analysis has not reached a state of maturity. Under a PSC, the goal is to study the origin and differentiation of basal evolutionary units, as judged from character evidence. Hence, there is a direct relationship between study of the geography of variation and the limits of phylogenetic species. The PSC therefore provides not only a defensible view of species, but provides a sounder framework for the study of speciation. Sexual selection will likely prove an important process in generating morphological diversity in speciation.