Heredity and Sex

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Columbia University Press, 1913 - Heredity - 284 pages
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Page 101 - This depends, not on a struggle for existence, but on a struggle between the males for possession of the females ; the result is not death to the unsuccessful competitor, but few or no offspring. Sexual selection is, therefore, less rigorous than natural selection. Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny.
Page 101 - Amongst birds, the contest is often of a more peaceful character. All those who have attended to the subject believe that there is the severest rivalry between the males of many species to attract, by singing, the females.
Page 114 - ... admire or even notice this display. The hen, the turkey, and the pea-fowl go on feeding while the male is displaying his finery ; and there is reason to believe that it is his persistency and energy rather than his beauty which wins the day.
Page 101 - The result is not death to the unsuccessful competitor, but few or no offspring. Sexual selection is, therefore, less rigorous than natural selection. Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny. But in many cases, victory depends not so much on general vigour, as on having special weapons, confined to the male sex.
Page 102 - I have seen the female sitting quietly on a branch, and two males displaying their charms in front of her. One would shoot up like a rocket, then suddenly expanding the snow-white tail like an inverted parachute, slowly descend in front of her, turning around gradually to show off both back and front.
Page 103 - The expanded white tail covered more space than all the rest of the bird, and was evidently the grand feature in the performance.
Page 217 - The failure to self-fertilize, which is the main problem, would seem to be due to the similarity in the hereditary factors carried by the eggs and sperm; but in the sperm, at least, reduction division has taken place prior to fertilization, and therefore unless each animal was homozygous (which from the nature of the case cannot be assumed possible) the failure to fertilize cannot be due to homozygosity. But both sperm and eggs have developed under the influence of the total or duplex number of hereditary...
Page 115 - In this chapter he described many of the dances, songs, and love-antics of birds, but regarded all such phenomena as merely "periodical fits of gladness." While, however, we may quite well agree with Mr. Hudson that conscious sexual gratification on the part of the female is not the cause of music and dancing performances in birds, nor of the brighter colors and ornaments that distinguish the male, such an opinion by no means excludes the conclusion that these phenomena are primarily sexual and intimately...
Page 114 - To conscious sexual selection, that is, the actual choice by the females of the more brilliantly-coloured males, I believe very little if any effect is directly due. It is undoubtedly proved that in birds the females do sometimes exert a choice ; but the evidence of this fact collected by Mr. Darwin (Descent of Man, chap, xiv.) does not prove that colour determines that choice, while much of the strongest evidence is directly opposed to this view.
Page 103 - Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me. I...

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