Can We Really Identify Species, Living or Extinct? - Schwartz - 1999

Given the profound effects regulatory genes - especially the better known homeobox genes - have on an organism's development, it is imperative that this level of what is obviously a genetic hierarchy is incorporated into our ideas on the origin and identification of species. Since regulatory genes are inherited in the same Mendelian fashion as structural genes, but the consequences of mutations affecting the former are more profound, they are of significance in discussions of species identification. Moreover, because nonlethal mutations typically arise in the recessive state, their spread via heterozygosis throughout the population will be silent. However, when homozygotes begin to appear, the morphologies resultant from the recessive mutations will emerge as if out of nowhere - thereby underscoring the role of morphology in both delineating species and being a potentially faithful reflection of phylogenetic relationships among taxa.

Keywords

Species - Homeobox gene - Regulatory gene - Structural gene - Mutation - Mendelism - Darwinism - Punctuation - Allopatric speciation

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