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Show 294 SEXUAL SELECTION: 1\rAl\IMALS. PART II. the adult male and with the young of both sexes, as I saw in the Gardens, neither the naked skin at the posterior end of tho bocly, nor the face, shew a trace of red. It appears, however, from some publi heel accounts, that the male does occasionally, or during certain seasons, exhibit some traces of the red. Although he is thus less ornamented than the female, yet in the larger size of his body, larger canine teeth, more developed whiskers, more prominent superciliary ridges, he follows the common rule of the male excelling the female. I have now given all the cases known to me of a difference in colour between the sexes of mammals. Tho colours of the female either do not differ in a sufficient degree from those of the male, or are not of a suitable nature, to afford her protection, and therefore cannot be explained on this principle. In some, perhaps in many cases, the differences may he the result of variations confined to one sex and transmitted to the same sex, without any good having been thus gained, and therefore without the aid of selection. We have instances of this kind with our domesticated animals, as in the males of certain cats .being rusty-red, whilst the females are tortoise-shell coloured. Analogous cases occur under nature; 1\fr. Bartlett has seen many black varieties of the jaguar, leopard, vulpine phalanger and wombat; and he is certain that all, or nearly all, were males. On the other hand, both sexes of wolves, foxes, and apparently of Ameriran squirrels, are occasionally bom black. Hence it is quite possible that with some mammals the blackness of the males, especial1y when this colour is congenital, may simply be the result, without the aid of selection, of one or more variations ha\'ing occurred, whieh from tho first wore IC IIAP. xna. ORNAMENTAL COLOURS. 295 sexually limited in their transmission. Nevertheless it can hardly be admitted that the diversified, vivid, .and contrasted colours of certain quadrupeds, for instance of the above-mentioned monkeys and antelopes, can thus be accouuted for. We should bear in mind that these colours do not appear in tho malo at birth .as in the case .of most ordinary variations, but only at or near matunty; and that unlike ordinary variations if the male be emasculated, they never appear or sub~ sequently disappear. It is on the whole a much more probable eonclusion that the strongly-marked colours and other . ornamental characters of male quadrupeds are beneficial to them in their rivalry with other males, and have consequently been acquired through sexual selection. The probability of this view is strengthened by the differences in colour between the sexes occurl" ing almost exclusively, as may be observed by going through the previous details, in those groups and subgroups of mammals, which present other and distinct secondary sexual characters ; these being likewise due to the action of sexual selection. Quadrupeds manifestly take notice of colour. Sir S. Baker repeatedly observed that the African elephant and rhinoceros attacked with special fury white or grey horses. I have elsewhere shewn 32 that half-wild horses apparently prefer pairing with those of the same colour, a.n~l that herds of fallow-deer of a different colour, though hvmg together, have long kept distinct. It is a more significant fact that a female zebra would not admit the addresses of a male ass until he was painted so as to resemble a zebra, and then, as John Hunter remarks, "she received him very readily. In this curious fact, 32 .: Tho Vnriltlion of Animals a.aJ Pla:1ts under Domost:cnt~on,' 186P, !VOl. u. p. 102, 103. |