Species

The Species Problem Arises 195

He (inaccurately, see above) cites Darwin a week after the publication of the Origin:

... I met Phillips, the palaeontologist, and he asked me, “How do you dene a species?”

I answered, “I cannot.” Whereupon he said, “At last I have found out the only true

denition,—any form which has ever had a species name!”^20

Similar views were held in the 1920s by British ichthyologist C. Tate Regan,^21 and
were named by Blackwelder the “taxonomic species concept,” and by Kitcher the
“cynical species concept.”^22
According to Poulton, though, species are interbreeding communities, syngamic
communities. This came later to be termed by Johannes Lotsy; briey, a Syngameon
as a neutral term for such communities, irrespective of their rank,^23 although as
Dobzhansky noted, Lotsy seemed to equate the syngameon with “species” anyway.^24
It underlay the gradual variation in forms from one end of a range of organisms to
another, which he referred to as a transition. But while when clear this made diagnosis
possible, there were cases in which it would fail: polymorphisms, seasonal dimor-
phisms, individual developmental adaptation (he calls it individual modification, and
cites Baldwin), geographical races and sub-species, and articial selection. Moreover,
says Poulton, interspecic sterility is not an infallible test of specicity, because, as
Darwin knew, related forms often can interbreed. Instead, sterility of hybrids is “an
incidental consequence of asyngamy,” of separation for a long period.^25 In addition,
asyngamy itself is usually the byproduct of asympatry,^26 although he allowed that Karl
Jordan was correct when he said that it could be due to mechanical incompatibility, or
the lack of t between sexual organs (in the 1896 report using the bird genus Papilio as
the test case).^27 Poulton also accepts Henry Bates’ 1862 claim of preferential mating.^28
All this notwithstanding, sterility is not, in his opinion, due to the action of selection.
This seminal paper, republished in 1905, was greatly inuential in setting up the terms,
both literally and metaphorically, of the twentieth century debate over species and
speciation. It subsequently inspired the writing of a text that summarized the issues as
understood at the end of the period in which neo-Lamarckian mechanisms were still
viable hypotheses, shortly before Dobzhansky’s paper and book.^29 We may usefully
date the Species Problem from Poulton’s paper.

(^20) Poulton cites More Letters of Charles Darwin 1903 [Darwin 1972, vol. I, 127]. As we see above, this
anecdote occurs in Darwin’s correspondence to Gray in 1857.
(^21) Regan 1926.
(^22) Blackwelder 1967, Kitcher 1984.
(^23) Lotsy 1931.
(^24) Dobzhansky 1941, 311.
(^25) Poulton 1908, 80.
(^26) Poulton 1908, 84.
(^27) Jorda n 1896; cf. later, Jordan 1905.
(^28) Bates 1862, 501:
(^) The process of the creation of a new species I believe to be accelerated in the Ithomiae and
allied genera by the strong tendency of the insects, when pairing, to select none but their exact
counterparts: this also enables a number of very closely allied ones to exist together, or the
representative forms to live side by side on the connes of their areas, without amalgamating.
(^29) Robson 1928.