CONTENTS 



Character Displacetnent 111 



Reduction of Fertility 277 

 Chromosomal Reanangements as Isolating Mechanisms 282 



Examples from Drosophila 282 



Oenothera and Translocation Complexes 283 



Chromosomal Mutants of Datura 287 



Evaluation of the Data 288 

 Failure of Isolating Mechanisms 290 



Introgressivc Hybridization 291 

 References 292 



Chapter Nineteen: Polyploidy 293 



Polyploidy, A Major Phenomenon in Plant Evolution 293 



Colchicine Induction of Polyploids 293 



The Gigas Habitus 294 

 Autotetraploidy in Evolution 296 

 Allotetraploidy in Experiment and in Nature 298 



Species Synthesis 301 



Genome Analysis 301 



The Wheats 303 



Polyploidy in Bromus: a Complex Case 304 

 Some Generalizations on Polyploidy 305 

 Polyploidy in the Animal Kingdom 306 

 References 307 



Chapter Twenty: Distribution of Species 308 



Island Life 308 



Genetic Drift on Oceanic Islands 309 



Rapid Selective Differentiation on Oceanic Islands 309 

 Endemism 312 

 Continental Distribution 314 

 Discontinuous Distribution and Bridges 315 



Corridors 315 



Filter Bridges 316 



Sweepstakes Routes 318 

 Problematical Distributions 320 



The Eastern Asia— Eastern North Atnerica Case 320 



Bipolar Mirror ism 320 



The Australia— South America Case 321 

 Theories of Distribution 322 



Continental Drift 



322 



The Age and Area Theory of Willis 322 

 Matthew's Theory on Climate and Evolution 324 

 References 326 



PART FIVE: RETROSPECT AND PROSPECT 327 



Chapter Twenty-one: Retrospect and Prospect 329 



Man and ihi- iMitnre 330 



Plant and Aninuil Breeding 331 



Distribution and Evolution of Wild Species 332 



Radiation and Evolution 333 



The l<uture of Man 334 



Evolution, a Young Science 336 

 References 337 



Index 339 



XVI 



