1 On Some Fundamental Concepts of Darwinian Biology.- Vitalism, Mechanism, and Compositionism.- Adaptedness and Adaptation.- Adaptedness to Survive and to Reproduce.- Adaptability.- Evolutionary Plasticity.- The Problem of Quantification of Adaptedness.- Darwinian Fitness.- Varieties of Natural Selection.- Darwinian Fitness and Adaptedness.- Evolutionary Opportunism and Adaptive Radiation.- Progressive Evolution.- References.- 2 Cave Ecology and the Evolution of Troglobites.- Animal Life in Caves.- The Cave Ecosystem.- Regressive Evolution in Cave Animals.- Speciation and Adaptation in Troglobites.- References.- 3 Molecular Biology and Bacterial Phylogeny.- The Evolution of Microorganisms in the Precambrian.- Microbial Fossils.- Bacteria as “Living Fossils”.- The Relationship Between Bacteria and Bluegreen Algae.- DNA Nucleotide Composition of Microorganisms.- Evolutionary Changes in Bacterial DNA.- DNA Homology.- Phenotypic Aspects of Bacterial Evolution.- Summary.- References.- 4 Evolutionary Implications of Sexual Behavior in Drosophila.- Types of Behavior.- Drosophila Preview.- Ontogeny of Mating Behavior.- Basic Courtship Patterns.- Adaptive Nature of Mating Behavior.- Specialized Mating Behavior of Hawaiian Species.- Summary of Mating Behavior.- Nature and Function of the Stimuli.- Mating Behavior of Other Diptera.- Significance of Drosophilid Mating Behavior.- Lek Behavior.- Sexual Isolation.- Intraspecific Variations.- Interspecific Behavior.- Origin of Sexual Isolation.- Conclusion.- References.- 5 Evolution of Photoreceptors.- Ciliary Photoreceptors.- Rhabdomeric Photoreceptors.- Ciliary Line of Evolution.- Rhabdomeric Line of Evolution.- Other Taxa.- Protostomes Versus Deuterostomes.- References.- 6 Evolution and Domestication of the Dog.- Taxonomy and Distribution of the Genus Canis.- Origin of the Dog.- Further Evidence for the Wolf as Ancestor to the Dog.- Time of Domestication.- The Place of Domestication.- The Process of Domestication.- Evolution of the Wolf.- Evolution of the Dog.- Evolution of Behavior in Dogs and Wolves.- Theoretical Considerations.- References.- 7 A Sampler of Human Behavioral Genetics.- The Nature of Psychological Traits.- The Twin Method.- Intellectual Abilities.- Schizophrenia.- Summary.- References.- 8 Suture-Zones of Hybrid Interaction Between Recently Joined Biotas.- Tabulation of Suture-Zone Examples.- The Individual Nearctic Zones.- Suture-Zones Outside North America.- Stabilization After Early Suturing.- Hybridization Outside Suture-Zones.- Discussion.- Acknowledgments.- Tables.- References.- Author Index.