物种起源导论02-家养条件下的变异.pptVIP

Introduction to The Origin of Species WANG Yuguo (School of Life Sciences, Fudan University) 复旦大学生命科学学院 王 玉 国 物 种 起 源 导 论 VARIATION UNDER DOMESTICATION 家养条件下的变异 CHAPTER I Introduction to The Origin of Species Causes of Variability Effects of Habit and the use and disuse of Parts—Correlated Variation—Inheritance Character of Domestic Varieties—Difficulty of distinguishing between Varieties and Species—Origin of Domestic Varieties from one or more Species Domestic Pigeons, their Differences and Origin Principles of Selection, anciently followed, their Effects Unconscious Selection Circumstances favourable to Mans power of Selection. Causes of Variability 变异的原因 The individuals of the same variety or sub-variety of our older cultivated plants and animals generally differ much more from each other, than do the individuals of any one species or variety in a state of nature. It seems pretty clear that organic beings must be exposed during several generations to the new conditions of life to cause any appreciable amount of variation; and that when the organisation has once begun to vary, it generally continues to vary for many generations. Changed conditions of life are of the highest importance in causing variability, both by acting directly on the organisation, and indirectly by affecting the reproductive system. The nature of the conditions is of subordinate importance in comparison with the nature of the organism in determining each particular form of variation. Effects of Habit and of the Use or Disuse of Parts; Correlated Variation; Inheritance 习性和器官的使用与否的效应； 相关变异；遗传 Plants Animals the increased use or disuse of parts changed habits the inherited effects Correlated variation monstrosities Character of Domestic Varieties; Difficulty of Distinguishing between Varieties and Species; Origin of Domestic Varieties from One or More Species. 家养变种的性状；区别变种与物种的困难； 家养变种起源于一个或多个物种 大麦 小麦 豌豆 罂粟 亚麻 Sheep and goats —— form no decided opinion Dogs —— sev