..................................... 182 Conclusions and Future Prospects . . . . . . . . . . . . . . . . .. . . 209 . . . . Micromolecules . . . . . . . . . . . . . . . . . . . . . . . . .. . . 209 . . . . . . . . Macromolecules . . . . . . . . . . . . . . . . . . . . . . . . .. . . 211 . . . . . . . . References ......................................... 213 xl xii Contents 3. Species Selection As a Causal Process ......... . . . . . . .. . . 249 Norman L. Gilinsky Introduction ........................................ 249 Differential Rates of Extinction . . . . . . . . . . . . . . . . . .. . . 251 . . . . . Differential Rates of Speciation: General Problems ........... 252 Differential Rates of Speciation: A Case for Reducibility ....... 254 Differential Rates of Speciation: A Case for Irreducibility Speciation via the Founder Principle . . . . . . . . . . . . .. . . 257 . . . Discussion ......................................... 262 Possible Examples of Species Selection: Hawaiian Drosophilidae ............................ 262 Possible Examples of Species Selection: Tertiary Neogastropoda ............................ 263 The Snail Example: Another Viewpoint ..... . . . . . . . . .. . . 267 . Species Selection and Randomness ..................... 268 Species Selection and Punctuated Equilibria . . . . . . . . . .. . . 269 . .