Ornithology, Evolution, and Philosophy 123

228 5 Biological Species and Speciation—Mayr’s First Synthesis
a given Galapagos Island and how this affects the size of the bill. It was Lack who
brought ecology into the evolutionary synthesis, Mayr (1947e) remarked in his
article on “Ecological factors in speciation.”
As to the origin of higher taxa Mayr (1942e: 298) concluded that this process
“is nothing but an extrapolation of speciation. All the processes and phenomena
of macroevolution and of the origin of the higher [taxa] can be traced back to
intraspecific variation, even though the first steps of such processes are usually
very minute.”
Isolating Mechanisms in Drosophila
Mating behavior is a very important isolating mechanism. Mayr wanted to know
how such species specificity was obtained. In a letter to R. C. Murphy, chairman of
the bird department at the AMNH, dated 18 March 1943, he explained:
“I have come to the conclusion in connection with my work on the origin of
species that a study of the factors which control the mating of animals is one of
the most badly needed research jobs in this field. There are certain factors, the socalled
isolating mechanisms, which prevent the mating of individuals which do not
belong to the same species. I’m planning to conduct a number of experiments […]
through which I want to determine how far the isolating mechanisms are inborn
and to what extent they are conditioned during the early life of the individual”
(cited from Cain 2002b).
AsafirststephewasgoingtoworkonDrosophila which would “make the
problems clearer.” Mayr spent mid-June to mid-July 1943 in Cold Spring Harbor
(Dobzhansky was in Brazil that year) and hoped to start experiments with birds
a few months later in the AMNH. A room on the top floor, the necessary cages
and individuals of three species of estrildid finches (Lonchura) wereacquired.
Alexander Seidel, the artist for Mayr’s books on the Birds of the Southwest Pacific
and the BirdsofthePhilippines(p. 150), was hired to run the bird colony. However,
the logistics of this project and several problems, e.g., how to keep the species
separated from each other, were overwhelming in view of other museum tasks
and his long commuting trips each day. 15 Mayr restricted research on isolating
mechanisms to Drosophila. His collaboration with Dobzhansky in Cold Spring
Harbor from 1944 until 1946, working at the same table, gave him another chance to
broaden his knowledge of evolution and evolutionary genetics. Mayr and his family
continued to spend 1–2 summer months there until 1952 (except in 1951 when they
were in Europe). He participated in seminars and discussions and interacted with
many other geneticists and scientists who were developing molecular biology at
that time. These annual stays at Cold Spring Harbor were invaluable for his future
career (pp. 243–250).
In a first set of experiments Dobzhansky and Mayr (1944j) tested geographical
strains of neotropical Drosophila willistoni. The methodology was developed by
15 Such experiments were later carried out successfully by Klaus Immelmann (1935–1987)
and his students in Bielefeld, Germany (e.g., Immelmann et al. 1978).