The mature Darwin 184582

CD's contributions to *ichthyology, for the period from 1845 to his death, were both indirect and direct. The indirect contribution, obviously, is that he developed the evolutionary context within which biology must now be done, if it is to mean anything, notwithstanding *creationism.

That story, culminating in the 1859 publication of the first edition of *Origin of Species, has been told in uncounted biographies and texts, and does not need rehashing here.

However, Origin, which ran in six editions during CD's lifetime, contains a multitude of direct references to fishes, notably on sexual selection, on relict forms (variants of the ganoid story, see above), on the position of fishes along the Complexity *scale, and on various *difficulties of the theory, i.e. the seeming lack of transitory forms to explain through natural selection the evolution of *eyes in fishes and other animals; *flying fishes; *swimbladders, erroneously presented as lung precursors; *electric fishes; the metamorphoses of flatfishes; the pregnancy of male

*seahorses; the sudden appearance of*teleosts in the *fossil record; and more. Also discussed are the impact of sea-surface temperatures and geographic barriers on ichthyofauna formation, including an interesting volte-face from the first edition, concerning the impact of the Isthmus of *Panama; and the results of his field experiments on how seeds in fish stomachs are distributed by piscivorous *birds. Overall, Origin is a firework of ichthyological ideas.

Many of these ideas are amplified in the books CD later wrote to boost the argument in Origin, notably *Variations (1871,1877), and *Descent (1871,1877), his only works with sections explicitly dedicated to fishes. In Variations, a two-page section deals with the origin and forms of *Goldfish. In Descent, a section discusses the *sex ratios of *Pike, *salmonids and *cyprinids, and another discusses the secondary sexual characters of a large number of fish *species, from *sharks and *rays to highly derived teleosts.

Thus, CD would have had a strong impact on ichthyology, had he decided to gather his thoughts on this group into a small book, similar, say, to the one he devoted to *Worms. He never assembled that book, however, and his impact on the discipline remained indirect - or absent, as illustrated by *Gunther's Introduction to the Study of Fishes.

The present volume may be seen as a belated entry on CD's behalf.

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