The Descent of Man and Selection in Relation to Sex, Vol. II (1st Edition)Darwin, Charles
Science
The Descent of Man and Selection in Relation to Sex, Vol. II (1st Edition)
Darwin, Charles
Evolution (Biology); Human beings -- Origin; Sex differences; Sexual dimorphism (Animals); Sexual selection in animals
It should be observed that, in some instances, the transference of
characters from the male to the female has been effected apparently at a
remote period, the male having subsequently undergone great changes,
without transferring to the female any of his later-gained characters.
For instance, the female and the young of the black-grouse (_Tetrao
tetrix_) resemble pretty closely both sexes and the young of the
red-grouse _T. Scoticus_; and we may consequently infer that the
black-grouse is descended from some ancient species, of which both sexes
were coloured in nearly the same manner as the red-grouse. As both sexes
of this latter species are more plainly barred during the
breeding-season than at any other time, and as the male differs
slightly from the female in his more strongly-pronounced red and brown
tints,[238] we may conclude that his plumage has been, at least to a
certain extent, influenced by sexual selection. If so, we may further
infer that the nearly similar plumage of the female black-grouse was
similarly produced at some former period. But since this period the male
black-grouse has acquired his fine black plumage, with his forked and
outwardly-curled tail-feathers; but of these characters there has hardly
been any transference to the female, excepting that she shews in her
tail a trace of the curved fork.
We may therefore conclude that the females of distinct though allied
species have often had their plumage rendered more or less different by
the transference in various degrees, of characters acquired, both during
former and recent times, by the males through sexual selection. But it
deserves especial attention that brilliant colours have been transferred
much more rarely than other tints. For instance, the male of the
red-throated bluebreast (_Cyanecula suecica_) has a rich blue breast,
including a sub-triangular red mark; now marks of approximately the same
shape have been transferred to the female, but the central space is
fulvous instead of red, and is surrounded by mottled instead of blue
feathers. The Gallinaceæ offer many analogous cases; for none of the
species, such as partridges, quails, guinea-fowls, &c., in which the
colours of the plumage have been largely transferred from the male to
the female, are brilliantly coloured. This is well exemplified with the
pheasants, in which the male is generally so much more brilliant than
the female; but with the Eared and Cheer pheasants (_Crossoptilon_
_auritum_ and _Phasianus Wallichii_) the two sexes closely resemble each
other and their colours are dull. We may go so far as to believe that if
any part of the plumage in the males of these two pheasants had been
brilliantly coloured, this would not have been transferred to the
females. These facts strongly support Mr. Wallace’s view that with birds
which are exposed to much danger during nidification, the transference
of bright colours from the male to the female has been checked through
natural selection.
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