Morphology And Molecules: An Integrated Comparison Of Phenotypic And Genetic Rates Of Evolution

The ability to successfully apply species and species concepts to real world problems such as biostratigraphy and conservation biology makes a strong argument for the existence of species (i.e., a level of organization that exists in the phenotype and genotype), whether or not we fully understand the processes involved in their origin. What we do know about the origin of biological species is drawn from four general perspectives: (1) Biological: variation within and among the broader phenotypes of closely related living organisms (including behavior, skeletal and nonskeletal morphology, physiology, and biochemistry, all generally limited to ecological timescales) and crossbreeding hybridization experiments; (2) Molecular: genetic data consisting of coded nucleotide sequences (DNA) ranging from short spans of a few dozen base pairs of uncertain placement or function to well documented genes to entire genomes; (3) Paleontological: documentation of patterns and rates of morphologic change in closely related lineages through geologic time (primarily skeletal phenotypes); and (4) Theoretical considerations: some informed by the other three areas and others pure and independent.