The "blind alley". Its significance for evolutionary theory.
Several scientists have apparently independently used the term "Blind Alley" to indicate that major evolutionary change has ceased. The failure to observe speciation through selection would indicate that obligatory sexual reproduction is incapable of producing progressive evolution. Favoring this conclusion is the evidence that sex determination has independently evolved and may be further correlated with the equally nonhomologous evolution of contemporary gametic sources in the same animal groups. To incorporate these facts into a meaningful theory demands the postulate of a presexual mode of reproduction which has been suggested as identical with the first meiotic division. A hypothetical scenario for macroevolution is presented.
Davison
J A
JA
University of Vermont, Burlington 05405.
D000818:Animals; D005075:Biological Evolution; D002875:Chromosomes; D002877:Chromosomes, Human; D005260:Female; D006801:Humans; D008297:Male; D012098:Reproduction; D012641:Selection, Genetic; D012732:Sex Determination Analysis; D013045:Species Specificity