D
davidford
Guest
comments by Ward and Ehrlich & Holm on the word “species.”
Credentials. Peter Douglas Ward is Professor of Geological Sciences and
Curator of Invertebrates, Thomas Burke Museum at the University of
Washington, and wrote In Search of Nautilus and The Natural History
of the Nautilus.
Ward, Peter Douglas. On Methuselah’s Trail: Living Fossils and the
Great Extinctions (NY: W.H. Freeman, 1992), 212pp. Foreword by Steven
M. Stanley. On 5:
_ _ …one {definition} advanced in 1942 by the great biologist Ernst
_ _ Mayr: “Species are groups of actually or potentially interbreeding
_ _ populations [of organisms] {Ward’s bracketing-df} which are
_ _ reproductively isolated from other such groups.” The key point is
_ _ that species are distinguished by the ability to breed successfully
_ _ from generation to generation.
_ _ This definition, although admirable {actually it’s not, as Ehrlich
_ _ & Holm demonstrate in their article} for currently living
_ _ organisms, is obviously useless to anyone who is studying fossils.
_ _ Though the fossil record yields many insights into the mode of life
_ _ of extinct organisms, it simply doesn’t tell us the juicy details
_ _ of who was sleeping with whom back in the Mesozoic. Nevertheless,
_ _ paleontologists refer to their fossils as belonging to species, and
_ _ in doing so are implying that the various individuals they place
_ _ within their species could, when alive, breed successfully. But
_ _ the truth is that fossils are grouped in species solely because of
_ _ morphological similarity. In other words, they are similar in form
_ _ and structure.
Credentials. According to their The Process of Evolution (1963), Paul
Ehrlich and Richard Holm were associate professors in the division of
systematic biology, dept of biological sciences, Stanford University.
According to Paul & Ann Ehrlich’s Extinction: The Causes and
Consequences of the Disappearance of Species (1981), Paul Ehrlich is a
professor of biological sciences and Bing Professor of Population
Studies at Stanford U.; as an evolution and ecology expert, he wrote
100+ scientific papers, a series of textbooks, some popular books, and
many articles.
Ehrlich, Paul R. and Richard W. Holm. “Patterns and Populations”
Science 137: 652-7 (1962). On 653:
_ _ Many concepts in population biology have low information content
_ _ and little or no operational meaning. In this category we should
_ _ place such concepts as “competition,” “niche,” “community,”
_ _ “climax,” “species,” “population fitness,” and to some extent
_ _ “population” itself. … As we shall demonstrate, the concept of
_ _ genetic (or “biological”) species, the idea of the community as a
_ _ unit, and many other concepts currently in subdisciplines of
_ _ population biology have much in common with the idea of absolute
_ _ time.
On 654:
_ _ One of the most widely accepted ideas of population biology is that
_ _ higher animals tend to occur in rather well-defined clusters called
_ _ species. Various theoretical definitions of species have been
_ _ attempted, and most of those accepted by modern evolutionists make
_ _ some statement about reproductive isolation between, but not
_ _ within, the clusters. In older definitions, assumptions concerning
_ _ the occurrence or non-occurrence of interbreeding are implicit.
_ _ … It seems clear {from the preceding discussion; get the
_ _ article} that the biological-species definition never has been
_ _ operational and never will be.
On 655:
_ _ The term species should be retained only in its original, less
_ _ restrictive sense of “kind.” There seems to be no reason why
_ _ quantitative methods should not be used to study phenetic
_ _ relationships (those based on similarity rather than imagined
_ _ phylogeny) at what we now loosely call the species level.
This is not on the topic at hand, but I found it interesting. On 656:
_ _ Few nonevolutionists realize that the term adaptation is one of
_ _ the least understood and most misused in population biology.
