OCR Text |
Show 302 , 'EXUAL SELECTION : MAMMALS. PAnT II. tho best of my ability tho sexual differences of anim.als belonging to all classes, I cannot avoid the conclusiOn that the curiously-arranged colours of many antelopes, though common to both sexes, are the result of sexual selection primarily applied to the male. The same conclusion may perhaps be extended to the tiger, one of the most beautiful animals in the world, the sexes of which cannot be distinguished by colour, even by the dealers in wild beasts. Mr. Wallace believes.38 that the striped coat of the tiger "so assi" milates with the vertical stems of the bamboo, as to ~:assist greatly in concealing him from his approaching "prey." But this view does not appear to me satisfactory. We have some slight evidence that his beauty may be due to sexual selection, for in two species of Felis analogous marks and colours are rather brighter in the male than in the female. The zebra is conspicuously striped, and stripes on the open plains of South Africa cannot afford any protection. Burchell 39 in describing a herd says, "their sleek ribs glistened in the "sun, and the brightness and regularity of their striped " coats presented a picture of extraordinary beauty, in "which probably they are not surpassed by any other "quadruped." Here we have no evidence of sexual selection, as throughout tho whole group of the Equidro the sexes are identical in colour. Nevertheless he who attributes the white and dark vertical stripes on the flanks of various antelopes to sexual selection, will probably extend the same view to the Royal Tiger and beautiful Zebra. vVe have seen in a former chapter that when young animals belonging to any class follow nearly the same as 'Westminster Review,' July 1, 1867, p. 5. 30 ' 'l'nwels in South Africa,' 1824, vol. ii. p. 315. CllAI'. XVlii. SPOTS AND STRIPES. 303 habits of life with their parents, and yet are coloured in a different manner, it may be inferred that they have retained the colouring of some ancient and extinct progenitor. In the family of pigs, and in the genus Tapir, the young are marked with longitudinal stripes, and thus differ from every existing adult species in these two groups. With many kinds of deer the young are marked with elegant white spots, of which their parents exhibit not a trace. A graduated series can be followed from the Axis deer, both sexes of which at all ages and during all seasons arc beautifully spotted (the male being rather more strongly coloured than the female)-to species in which neither the old nor the young are spotted. I will specify some of the steps in this series. The Mantchurian deer (Cerv~~s Mantchuricus) is spotted during tho whole year, but the spots are much plainer, as I have seen in the Zoological Gardens, during the summer, when the general colour of tho coat is lighter, than during the ' winter, when the general colour is darker and the horns a7e fully developed. In the hog-deer (Hyelaphus porc'mus) the spots are extremely conspicuous during the summer when the coat is reddish-brown, but quite disappear during tho winter when the coat is brown:to In both these species the young are spotted. In the Vil'ginian <leer the young are likewise spotted, and about five per cent. of the adult animals living in Judge Caton's park, as I am informed by him, temporarily exhibit at the period when the red summer coat is being replaced by the bluish winter coat, a row of spots on each flank, which are always the same in 40 Dr. Gmy, ' Gleanings from the l\1enagerie of Knowsley,' p. 64. Mr. Blyth, in SJ1eaking ('Land and Water,' 186!), p. 42) of tho ho,.. deer of Ceylon, says it is more brightly spotted with white than tho common hog-deer, at lhr senson when it renews its horns. |