Evolution__3rd_Edition

..
Figure 1.10
(a) Julian Huxley (1887–1975)
in 1918. (b) Ernst Mayr
(1904–), on the right, on an
ornithological expedition in
New Guinea in 1928, with his
Malay assistant.
. . . and led to a new understanding
of speciation ...
(a) (b)
CHAPTER 1 / The Rise of Evolutionary Biology 17
acquired characters. A major book, The Variation of Animals in Nature, by two systematists,
G.C. Robson and O.W. Richards (1936), accepted neither Mendelism nor
Darwinism. Robson and Richards suggested that the differences between species are
non-adaptive and have nothing to do with natural selection. Richard Goldschmidt
(1878–1958), most famously in his book on The Material Basis of Evolution (1940),
argued that speciation was produced by macromutations, not the selection of small
variants.
The question of how species originate is closely related to the questions of population
genetics, and Fisher, Haldane, and Wright had all discussed it. Dobzhansky and
Huxley emphasized the problem even more. They all reasoned that the kinds of
changes studied by population geneticists, if they took place in geographically separated
populations, could cause the populations to diverge and eventually evolve into
distinct species (Chapter 14). The classic work, however, was by Ernst Mayr: Systematics
and the Origin of Species (1942). Like many classic books in science, it was written
as a polemic against a particular viewpoint. It was precipitated by Goldschmidt’s
Material Basis but criticized Goldschmidt from the viewpoint of a complete and differing
theory a the modern synthesis a rather than narrowly refuting him and it therefore
has a much broader importance. Both Goldschmidt and Mayr (Figure 1.10b) were
born and educated in Germany and later emigrated to the USA. Mayr left in 1930 as a
young man, but Goldschmidt was 58 and had built a distinguished career when he left
Nazi Germany in 1936.
A related development is often called the “new systematics,” after the title of a book
edited by Julian Huxley (1940). It refers to the overthrow of what Mayr called the
“typological” species concept and its replacement by a species concept better suited to
modern population genetics (Chapter 13). The two concepts differ in what sense they