1. Chapter 19 Evolutionary Patterns, Rates and Trends

2. Natural Selection  Results in adaptations of a population to biotic and abiotic environment  Evolution by Natural Selection requires: Variation Inheritance Differential adaptiveness Differential reproduction

3. Macroevolution  Large scale patterns, trends and rates of change among families and other more inclusive groups of species

4. Species  Population whose members have the potential to interbreed and produce viable, fertile offspring  Speciation Splitting of one species into 2 or more Transformation of 1 species into a new species  Final result:  Changes in a gene pool allele and genotypic frequencies

5. Reproductive Isolation  Inability to reproduce with members of another species  Cornerstone of the biological species concept  Speciation is the attainment of reproductive isolation  Reproductive isolation arises as a by-product of genetic change

6. Pre-Zygotic Isolating Mechanisms  Habitat Isolation occupy different habitats  Temporal Isolation reproduce at different times of the year  Mechanical Isolation animal genitalia or plant floral structures are incompatible  Behavioral Isolation courtship behaviors

7. Albatross courtship Reproductive Isolation

8. Pre-Zygotic Isolating Mechanisms  Gamete Isolation sperm of 1 species may not be able to survive in the reproductive tract of another species  Polyploidy occurs in plants can’t reproduce with plants that have polyploidy

9. Post Zygotic Isolating Mechanisms  Zygote Mortality Zygote with 2 different chromosome sets may fail to go thru mitosis (gastrulation) Incompatible instructions  Hybrid Sterility Hybrid survives but cannot reproduce  F 2 Fitness Hybrid is fertile, but F 2 has reduced fitness

10. Mechanisms of Speciation  Allopatric Speciation  Sympatric Speciation  Parapatric Speciation

11. Models of speciation Models of Speciation

12. Allopatric Speciation  Speciation in geographically isolated populations  Some sort of barrier arises and prevents gene flow  Effectiveness of barrier varies with species  Species separated by geographic barriers will diverge genetically  If divergence is great enough it will prevent inbreeding even if the barrier later disappears

13. Allopatric Speciation  Adaptive Radiation burst of divergence single lineage gives rise to many new species new species fill vacant adaptive zone adaptive zone is “way of life”

14. Allopatric speciation on an archipelago Models of Speciation

15. Sympatric Speciation  Species forms within the home range of the parent species  Occurs without a barrier

16. Models of speciation Models of Speciation

17. Sympatric speciation in wheat Possible Evolution of Wheat

18. Models of speciation Models of Speciation

19. Parapatric Speciation  Neighboring populations become distinct species while maintaining contact along a common border  Adjacent populations evolve into distinct species while maintaining contact along a common border

20. Parapatric Speciation BULLOCK’S ORIOLE BALTIMORE ORIOLE HYBRID ZONE

21. Patterns of Change in a Lineage  Cladogenesis Branching pattern Lineage splits, isolated populations diverge  Anagenesis No branching Changes occur within single lineage Gene flow throughout process

22. Evolutionary tree diagram Evolutionary Trees

23. Evolutionary tree for plants Evolutionary Trees

24. Gradual Model  Speciation model in which species emerge through many small morphological changes that accumulate over a long time period  Fits well with evidence from certain lineages in fossil record

25. Punctuation Model  Speciation model in which most changes in morphology are compressed into brief period near onset of divergence  Supported by fossil evidence in some lineages

26. Taxonomy  Field of biology concerned with identifying, naming, and classifying species  Somewhat subjective  Information about species can be interpreted differently

27. Phylogeny  The scientific study of evolutionary relationships among species  Practical applications Allows predictions about the needs or weaknesses of one species on the basis of its known relationship to another

28. Examples of Classification

29. Classification systems Six-Kingdom Scheme

30. Constructing a Cladogram A Cladogram

31. Interpreting a Cladogram A Cladogram

32. Constructing a Cladogram