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| Science Forum Index » Bio Evolution Forum » Paper: George Romanes, William Bateson, and Darwin... |
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| Robert Karl Stonjek... |
 Posted: Thu Oct 29, 2009 5:42 am |
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George Romanes, William Bateson, and Darwin's ‘weak point’
Donald R. Forsdyke
Department of Biochemistry, Queen's University, Kingston, Ontario, Canada
K7L 3N6
Abstract
Thomas Huxley identified as Darwin's ‘weak point’ the failure of breeders
when crossing varieties within a species to simulate the sterility of
hybrids derived from crosses between allied species. As a result of the
sterility, the parents of a hybrid were, in an evolutionary sense,
reproductively isolated from each other, so they would be members of
distinct species. In his theory of ‘physiological selection’, Romanes
postulated germline ‘collective variations’ that accumulate in certain
members of a species; these members are thus ‘physiological complements’
producing fertile offspring when mutually crossed, but sterile offspring
when crossed with others. Unlike Darwin's natural selection, which secured
reproductive isolation of the fit by elimination of the unfit, physiological
selection postulated variations in the reproductive system that were not
targets of natural selection; these sympatrically isolated the fit from the
fit, leaving two species where initially there had been one. Bateson
approved of physiological selection. He noted that Mendel's ‘unit characters
’ were ‘sensible manifestations’ of what we now refer to as ‘genes’, but
postulated a ‘residue’, distinct from genes, that might affect gene flow
between organisms and so originate species. The reproductive isolation of
the parents of a sterile hybrid was due to two complementing non-genic
factors (the ‘residue’) separately introduced into the hybrid by each
parent. Modern studies, especially of yeast hybrids, support the
Romanes–Bateson viewpoint.
Source: The Royal Society
http://rsnr.royalsocietypublishing.org/content/early/2009/10/27/rsnr.2009.0045.abstract?papetoc
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| forsdyke... |
| Posted: Tue Nov 03, 2009 7:17 am |
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