Genetics, Paleontology, and Macroevolution ebook is available to be downloaded here now.
- Title: Genetics, Paleontology, and Macroevolution, Second Edition
- Author: JEFFREY S. LEVINTON
- Publisher: Cambridge
- Pages: 635
Evolutionary biology enjoys the peculiar dual status of being that subject which clearly unites all biological endeavors, while occasionally seeming to be nearly as remote from complete understanding as when Darwin brought it within the realm of materialistic science. Somehow, the basic precepts first proposed by Darwin have never been either fully accepted or disposed, to be followed by a movement toward further progress in some other direction. The arguments of today – the questions of natural selection and adaptation, saltation versus gradualism, and questions of relatedness among organisms – are not all that different from those discussed 100 years ago, even if the research materials seem that much more sophisticated.
Darwin espoused thinking in terms of populations. His approach was open to experimentation, but this had to await the (re)discovery of genetics half a century later, before a major impediment to our understanding could be thrown aside. As it turned out, the rediscovery of genetics was initially more confusing than helpful to our understanding of evolution. The rediscovery of genetically transmissible discrete traits revived saltationism, and it took over a decade for biologists to realize that there was no conflict between the origin of discrete variants and the theory of natural selection. In the twentieth century, the focus of experimentalists moved toward processes occurring within populations. But many of the inherently most fascinating questions lie at higher taxonomic levels, or at greater distances of relationship than between individuals in a population.
The questions are both descriptive and mechanistic. We would like to know just how to describe the difference between a lizard and an elephant, in terms that would make it possible to conceive of the evolution ary links between them. We are only now beginning to do this, principally at the molecular genetic level. Differences in nucleotide sequences are beginning to have more meaning at this level, especially because of the emerging knowledge of gene regulation. But we would also like to understand the mechanisms behind the evolutionary process at higher levels of morphological organization. This inevitably involves a knowledge of history with all the limitations that that subject embraces. Just how can we be sure about biological historical facts? Surely the fossil record must come into play here, even if it is scattered in preservation.