Species

216 Species

The new geneticists tended, then, toward an eliminativist view on species, in what

they perceived was the tradition of Darwin: sure, the lineages split and this was real,

but the rank of the splitting was manifold and had no universally common criteria

that could be recognized. There was a division in the way the Synthesis Darwinians

approached species, which can be traced back to Darwin’s own published ambiguity

on the subject. Into this ambiguity of opinion came Ernst Mayr.

Ernst Mayr and the Biospecies Concept

Mayr was a German ornithologist who had left Germany well before the war and
came to America to the American Museum of Natural History and then to Harvard
after spending a number of years in New Guinea and the Solomon Islands studying
bird populations and distributions.^33 He was motivated to address the “species prob-
lem” because of the publication of another book, opposed to Dobzhansky’s approach,
by geneticist Richard Goldschmidt, who became Mayr’s bête noire for many years
to come.^34 Goldschmidt proposed that species evolved in a single step, through mac-
romutations involving chromosomal repatterning to form “hopeful monsters”^35 in
what is often called “saltation” (i.e., the opposite of natura non facit saltum quoted
by Darwin). Goldschmidt repeatedly referred to species being separated by “bridge-
less gaps,”^36 a phrase he took from Turesson,^37 ignoring the fact that Turesson then
went on to give a Darwinian account of species formation. Goldschmidt rejected the
Darwinian idea that subspecific races were incipient species entirely, which seems to
have motivated Mayr’s ire and to have informed his allopatric account of speciation
later.
Mayr was invited to give a series of talks on speciation as part of the Jesup
Lectures in 1941 at Columbia University’s Zoology Department. He was later invited
to publish sufficient material to fill an entire volume for Columbia University Press
after the other lecturer, Edgar Anderson, fell ill.^38 The result was the single most
widely referred to volume of the synthesis.
Basically, this work is a discussion at length of the modes of speciation according
to the best knowledge of the day, and much of what Mayr discussed remains valid. In
the case of “ring-species” for example, his discussions remain the canonical ones.^39
He also introduced several terms, including allopatry^40 and sibling species,^41 which

(^33) Hull 1988, 66f.
(^34) Goldschmidt 1940.
(^35) Op. cit. 390–393; it should be clear now that the term “monster” here refers to a sport or sudden varia-
tion from the type.
(^36) Cf. op. cit., 143.
(^37) Turesson 1927, 100.
(^38) Cf. xvii, of the new Introduction to the 1999 reissue of his 1942.
(^39) Mayr 1999, 180–185. However, some of the canonical examples are being disputed. Recently, molec-
ular analysis of the Larus argentatus (Herring Gull) complex has indicated that they are, in fact,
isolated gene pools [Liebers et al. 2004] and the Parus major (Great Tit) complex, while it does
interbreed to some extent, is a good set of phylogenetic species [Kvist et al. 2003].
(^40) Mayr 1999, 149.
(^41) Op. cit., 151.