Darwin on Trial by Johnson Phillip E

Author:Johnson, Phillip E. [Johnson, Phillip E.]
Language: eng
Format: azw3
ISBN: 9781621575139
Publisher: Regnery Publishing
Published: 2015-11-30T16:00:00+00:00

1 The “phenotype” refers to the visible features of an organism, or more precisely to the detectable expression of the interaction between the genotype and the environment. The genotype is the invisible package of genes that directs the growth of the phenotype in the reproductive process.

2 In this chapter I am taking the neutral theory and the molecular clock data at face value, but I should note that the whole subject is currently embroiled in complex controversy. According to a recent review article by Roger Lewin, “The theory that we can date the birth of new species by charting the steady accumulation of mutations over evolutionary time is in serious trouble.” It seems that the data are too even for a selectionist interpretation, and not even enough for a neutralist explanation. According to Allan Wilson, “many biologists who make mathematical models of the evolutionary process are coming to believe many of the mutations accumulated during molecular evolution are not neutral. They argue that instead of proceeding smoothly, molecular evolution might be characterized by long periods of inactivity punctuated by bursts of change. If they are right, the challenge of finding an explanation for the molecular clock phenomenon grows.” About all that can be said for now is that a pattern of relationships exists at the molecular level which is roughly consistent with the relationships determined by visible features, and which could have come about by some combination of variable and constant-rate evolution.

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