Ornithology, Evolution, and Philosophy 123

376 12 Summary: Appreciation of Ernst Mayr’s Science
(1942e), which synthesized new systematics, evolution and population genetics,
Mayr assumed a central position in the evolutionary synthesis and evolutionary
studies in the United States. He emphasized repeatedly how large a role systematics
played in the evolutionary synthesis, because this is so often ignored. The
naturalists-systematists solved the problem of speciation, but they also showed that
there was a smooth, unbroken connection between evolution at the species level
and evolution of higher taxa and of major evolutionary innovations (macroevolution).
There were no discontinuities (saltations), because the units of evolution
are populations and populations can only change gradually, more slowly or faster
depending on the size of the population.
Mayr’s work as a curator of ornithology at the American Museum of Natural
History in New York (1931–1953) on the patterns of geographical variation and
speciation in the birds of New Guinea, Melanesia, Polynesia, Micronesia—the first
two areas he visited on expeditions during the late 1920s—formed the empirical
basis for his theoretical work on species, speciation and general problems of evolution
in animals. Evolution is gradual and continuously progressing, yet the species
of a local fauna, the products of evolution, are sharply separated by unbridgeable
gaps. Building on the work of several earlier systematists, Mayr solved this apparent
contradiction with the theory of allopatric speciation, the differentiation of geographically
separated (allopatric) populations and their later contact and overlap
of their ranges without hybridization after genetic-reproductive isolation between
them had been completed. In later years he agreed that in some groups of animals
species may also arise without geographic barriers (in sympatry). In the field of
zoogeography he discussed the composition, origins, history and boundaries of
faunas and established the theory of island biogeography already in 1933(j). He was
a prime mover of evolutionary studies in the United States since the mid-1940s, one
of the founders of the Society for the Study of Evolution and the founding editor
of its journal Evolution (1947–1949). During these years he also discussed many
problems with a bearing on the history and philosophy of biology like historical
aspects of the study of geographical variation, the theoretical species concept, and
the concept of “population thinking,” on the basis of which Charles Darwin had
conceptualized his thesis of natural selection.
Mayr’s career is an example for important theoretical work in the biological
sciences being based on empirical research in ornithology. He published numerous
papers and three books as an ornithologist during the 1920s to the 1950s. Among
the almost 300 titles on birds just over half are descriptive faunistic works and
taxonomic revisions; about 30% treat natural history topics (life history, migration,
and molt), and the rest refer to biogeography and speciation (Gill 1994). Early in his
ornithological career Mayr also developed an interest in zoological nomenclature,
particularly in the stability of scientific names of birds and other animals. During
the 1950s and 1960s, he published actively in this field. Beginning with his work
on Systematics and the Origin of Species (1942e) ornithological papers dropped to
about 25% and less over the next several decades.
In 1953 Mayr accepted the position of an Alexander Agassiz Professor of Zoology
at the Museum of Comparative Zoology, Harvard University, Cambridge,