Problems of genetics / by William Bateson.

  • Bateson, William, 1861-1926.
Date:
1913
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Problems of genetics / by William Bateson. Source: Wellcome Collection.

    143/290 (page 121)
    VARIATION AND LOCALITY 121 bars on the wings, but the female is somewhat thrush-like in colour. In the island of Porto Rico there is a form called xan~ thomus, in which both sexes are like the males of the mainland. A similar species called humeralis, also with both sexes male-like, lives in Cuba. The island of Cuba, curiously enough, has also a distinct species named assimilis, in which the female is a dull black all over, though the male is like the mainland type. So also may local races differ in respect of variability. Ar- gynnis paphia, the Silver Washed Fritillary, through a great part of its distribution has only one female form. In the English New Forest a second female form, valesina, co-exists with the ordinary paphia female. But in the southern valleys of the Alps the valesina female is much the commoner of the two, and indeed in some localities where the species is abundant, I have seen no paphia females in many days collecting. The beetle Gonioctena variabilis furnishes an illustration of a comparable phenomenon affecting the male sex. In 1894 and 1895 I studied the curious colour variations of this species es¬ pecially in the neighbourhood of Granada, and Mr. Doncaster ten years later repeated the observations on the same ground, and also collected the insect in other places in the south of Spain. The distinctions are not easy to give in words and the reader is referred to the colour plate accompanying my paper.® The essential fact is that the males commonly have the elytra red with black spots and the females for the most part have greenish grey elytra with black stripes. In some localities a large minority of males closely resemble the female type, being identical in colour and then only distinguishable by structural differences. In two Granada localities I found the proportion of such males quite different. In the Darro valley about 38 per cent, (in ® Proc. Zool. Soc., 189s, p. 850. Plate. Many points beyond that mentioned above are involved in this remarkable case. For example, not only are there males like females, but a small proportion of females resemble the ordinary male type. The stripes are not merely the spots produced, for they occupy different anatomical positions. The spots almost always go with a black ventral surface, but the striped forms nearly always have that region testaceous. Spartium retama, the food-plant, will not grow in England, but if it could be naturalised in America the whole problem might be investigated there and results of exceptional interest would almost cer¬ tainly be attained.