Ornithology, Evolution, and Philosophy 123

University Student in Greifswald and Berlin 29
Another interesting question is the rate of differentiation (“Polish Serin” [H]).
Supporters of the mutation theory should answer this question: In which way
does the established form disappear from its range? Possibly the mutant is more
strongly expansive. The peculiar phenomena of convergence which caused so
many errors in systematics need to be taken thoroughly into consideration.
Very many ornithologists would appreciate a comprehensive treatment of these
problems. Surely such a study would suit you. […]
With ornithological greetings. Sincerely yours, Ernst Mayr.
Notes:
[A] In cases of clinal or stepped clinal geographical variation, A.B. Meyer and
L.W. Wiglesworth (1898) and L. Wiglesworth (1898) had proposed to assign
subspecies names only to the endpoints and to selected intermediate stages in
the character progression.
[B] This is a reference to the hybridization between the white-headed and stripeheaded
forms of the Long-tailed Tit (Aegithalos caudatus) in central Europe.
[C] Mayr distinguished here between primary and secondary intergradation.
[D] Görnitz (1923: 498) had concluded “that the majority of the geographical
subspecies are not due to the effect of natural selection but originated through
the effect of climatic factors.”
[E] This is a reference to two pairs of sibling species (Luscinia luscinia/L. megarhynchos
and Certhia brachydactyla/C. familiaris) whose members probably
originated in geographical isolation from their respective common ancestors
and are today in secondary contact along a narrow (nightingales) or broad
(treecreepers) zone of overlap in central Europe.
[F] The Protestant pastor and ornithologist Otto Kleinschmidt (1870–1954) had
proposed a typological species concept (“Formenkreis”) and the independent
origin (creation) of all animal species.
[G] In his excellently illustrated monograph series “Berajah” (1905–1936) Kleinschmidt
had discussed geographical variation and range expansion of numerous
species.
[H] Several subspecies of the Serin (Serinus serinus) had been described from
regions (Germany, Poland), which this bird had colonized only during the
last century. In his dissertation on “The expansion of the Serin” Mayr (1926e)
was able to prove that the Serin finch does not differ in these latter areas
taxonomically from the populations in the Mediterranean region.
When I sent a copy of the above letter to Ernst Mayr in 1992, he was totally
surprised and answered (transl.):
“I am terribly amused at my forwardness with Stresemann. No doubt this is part
of the reason why in the Stresemann family I was always referred to as the fresh
(‘freche’) young Mayr. I admire the patience with which Stresemann tolerated me
and my letters. He must have appreciated my genuine deep interest in science.
I had completely forgotten all about this letter and even reading and re-reading it
now does not trigger any remembrance.”