Table of Contents
PREFACE .............................................................................................. 001
INTRODUCTION ............................................................................... 015
CHAPTER I VARIATION UNDER
DOMESTICATION ........................................... 021
CAUSES OF VARIABILITY...............................................................022
EFFECTS OF HABIT AND OF THE USE OR DISUSE OF
PARTS; CORRELATED VARIATION; INHERITANCE .......027
CHARACTER OF DOMESTIC VARIETIES; DIFFICULTY
OF DISTINGUISHING BETWEEN VARIETIES AND
SPECIES; ORIGIN OF DOMESTIC VARIETIES FROM
ONE OR MORE SPECIES...............................................................032
BREEDS OF THE DOMESTIC PIGEON, THEIR
DIFFERENCES AND ORIGIN .....................................................037
PRINCIPLES OF SELECTION ANCIENTLY FOLLOWED,
AND THEIR EFFECTS .................................................................. 046
UNCONSCIOUS SELECTION.......................................................... 051
·I?
CIRCUMSTANCES FAVOURABLE TO MAN’S POWER OF
SELECTION ......................................................................................058
CHAPTER II VARIATION UNDER
NATURE ............................................................ 063
INDIVIDUAL DIFFERENCES ........................................................ 065
DOUBTFUL SPECIES......................................................................... 068
WIDE-RANGING, MUCH DIFFUSED, AND COMMON
SPECIES VARY MOST....................................................................077
SPECIES OF THE LARGER GENERA IN EACH COUNTRY
VARY MORE FREQUENTLY THAN THE SPECIES OF
THE SMALLER GENERA ............................................................. 079
MANY OF THE SPECIES INCLUDED WITHIN THE LARGER
GENERA RESEMBLE VARIETIES IN BEING VERY CLOSELY,
BUT UNEQUALLY, RELATED TO EACH OTHER, AND IN
HAVING RESTRICTED RANGES ..............................................082
SUMMARY ........................................................................................... 084
CHAPTER III STRUGGLE FOR
EXISTENCE ...................................................... 087
THE TERM, STRUGGLE FOR EXISTENCE, USED
IN A LARGE SENSE........................................................................090
GEOMETRICAL RATIO OF INCREASE.......................................091
NATURE OF THE CHECKS TO INCREASE .............................. 095
? II ?
COMPLEX RELATIONS OF ALL ANIMALS AND PLANTS TO
EACH OTHER IN THE STRUGGLE FOR EXISTENCE ...... 099
STRUGGLE FOR LIFE MOST SEVERE BETWEEN
INDIVIDUALS AND VARIETIES OF THE SAME SPECIES .... 104
CHAPTER IV NATURAL SELECTION;
OR THE SURVIVAL OF THE FITTEST .......... 109
SEXUAL SELECTION ........................................................................ 119
ILLUSTRATIONS OF THE ACTION OF NATURAL
SELECTION, OR THE SURVIVAL OF THE FITTEST ...........122
ON THE INTERCROSSING OF INDIVIDUALS ........................ 131
CIRCUMSTANCES FAVOURABLE FOR THE PRODUCTION
OF NEW FORMS THROUGH NATURAL SELECTION .......137
EXTINCTION CAUSED BY NATURAL SELECTION .............. 145
DIVERGENCE OF CHARACTER ................................................... 147
THE PROBABLE EFFECTS OF THE ACTION OF NATURAL
SELECTION THROUGH DIVERGENCE OF CHARACTER
AND EXTINCTION, ON THE DESCENDANTS OF A
COMMON ANCESTOR...................................................................152
ON THE DEGREE TO WHICH ORGANISATION TENDS
TO ADVANCE ................................................................................. 163
CONVERGENCE OF CHARACTER............................................... 168
SUMMARY OF CHAPTER .................................................................171
? III ?
CHAPTER V LAWS OF VARIATION ................. 175
EFFECTS OF THE INCREASED USE AND DISUSE OF PARTS,
AS CONTROLLED BY NATURAL SELECTION .................... 178
ACCLIMATISATION ........................................................................ 184
CORRELATED VARIATION .......................................................... 188
COMPENSATION AND ECONOMY OF GROWTH ................ 192
MULTIPLE, RUDIMENTARY, AND LOWLY-ORGANISED
STRUCTURES ARE VARIABLE ..................................................194
A PART DEVELOPED IN ANY SPECIES IN AN
EXTRAORDINARY DEGREE OR MANNER, IN
COMPARISON WITH THE SAME PART IN ALLIED
SPECIES, TENDS TO BE HIGHLY VARIABLE ....................... 195
SPECIFIC CHARACTERS MORE VARIABLE THAN GENERIC
CHARACTERS .................................................................................199
SECONDARY SEXUAL CHARACTERS VARIABLE .................201
DISTINCT SPECIES PRESENT ANALOGOUS VARIATIONS,
SO THAT A VARIETY OF ONE SPECIES OFTEN ASSUMES
A CHARACTER PROPER TO AN ALLIED SPECIES, OR
REVERTS TO SOME OF THE CHARACTERS OF AN EARLY
PROGENITOR ................................................................................ 204
SUMMARY .............................................................................................213
? IV ?
CHAPTER VI DIFFICULTIES OF THE
THEORY .............................................................217
ON THE ABSENCE OR RARITY OF TRANSITIONAL
VARIETIES ........................................................................................ 219
ON THE ORIGIN AND TRANSITION OF ORGANIC BEINGS
WITH PECULIAR HABITS AND STRUCTURE .....................226
ORGANS OF EXTREME PERFECTION AND
COMPLICATION ............................................................................233
MODES Of TRANSITION ............................................................... 238
SPECIAL DIFFICULTIES OF THE THEORY OF NATURAL
SELECTION ...................................................................................... 243
ORGANS OF LITTLE APPARENT IMPORTANCE, AS
AFFECTED BY NATURAL SELECTION ...................................253
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