Evolution__3rd_Edition

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Full Contents xxi
23.3.2 The best studied mass extinction occurred at
the Cretaceous–Tertiary boundary 651
23.3.3 Several factors can contribute to mass extinctions 653
23.4 Distributions of extinction rates may fit a power law 655
23.5 Changes in the quality of the sedimentary record through time are
associated with changes in the observed extinction rate 657
23.6 Species selection 658
23.6.1 Characters that evolve within taxa may influence extinction
and speciation rates, as is illustrated by snails with
planktonic and direct development 658
23.6.2 Differences in the persistence of ecological niches will
influence macroevolutionary patterns 664
23.6.3 When species selection operates, the factors that control
macroevolution differ from the factors that control
microevolution 665
23.6.4 Forms of species selection may change during mass
extinctions 666
23.7 One higher taxon may replace another, because of chance,
environmental change, or competitive replacement 669
23.7.1 Taxonomic patters through time can provide evidence
about the cause of replacements 669
23.7.2 Two bryozoan groups are a possible example of
a competitive replacement 670
23.7.3 Mammals and dinosaurs are a classic example of
independent replacement, but recent molecular
evidence has complicated the interpretation 671
23.8 Species diversity may have increased logistically or exponentially
since the Cambrian, or it may have increased little at all 674
23.9 Conclusion: biologists and paleontologists have held a range of
views about the importance of mass extinctions in the history of life 677
Summary Further reading Study and review questions
Glossary 682
Answers to Study and Review Questions 690
References 699
Index
Color plate section between pp. 70 and 71
733