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PATTERNS IN EVOLUTION

PATTERNS IN EVOLUTION. Patterns in Evolution. Divergent. Convergent. Parallel. Divergent Evolution. Divergent evolution is the evolution of different species (populations) from a common ancestral species (population). . Homologous Structures.

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PATTERNS IN EVOLUTION

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  1. PATTERNS IN EVOLUTION

  2. Patterns in Evolution Divergent Convergent Parallel

  3. Divergent Evolution • Divergent evolution is the evolution of different species (populations) from a common ancestral species (population).

  4. Homologous Structures • Homologous features are evidence of divergent evolutionary relationship.

  5. Adaptive Radiation • Adaptive radiation is a special case of divergent evolution • Adaptive Radiation is when a cluster of different species evolve from a single ancestral species

  6. Adaptive Radiation

  7. Parallel Evolution • Parallel evolution occurs when related species evolve similar features • independently.The two species then evolve in much the same way over time, probably in response to similar environmental selection pressures.

  8. Parallel Evolution

  9. Convergent Evolution • Convergent evolution is the evolution of similar features in unrelated species, through selective factors such as similar environments or diets • Over time selection pressures may act on distantly related species to produce superficial similarities. • It appears the different species are becoming more similar.

  10. Analogous Structures • Anatomical structures that are found in different groups of organisms, such as wings in birds and butterflies, are described as analogous features; that is, they serve the same function but have evolved independently.

  11. Convergent Evolution • The eyes of octopuses and vertebrates are a striking example of convergent evolution. • Even though octopuses and vertebrates both have eyes, this does not mean that they are closely related. • From an evolutionary point of view, analogous features are not helpful in the discovery of ‘who is related to whom’.

  12. Convergent Evolution

  13. Convergent Evolution

  14. Co Evolution • Co-evolution is when changes in one species occurs because of changes in another species. • This way the relationship between the two is maintained

  15. Macro-evolution • Change within a species is termed macro-evolution. • There are two views on the rate of change for macro evolution • Gradualism • Punctuated Equilibrium

  16. Evolution: gradual or intermittent? The punk ekk model proposes that species persist unchanged over very long periods and that evolution of new species mainly occurs over much shorter time periods. Gradualism model proposes that the rate of evolutionary change was slow and that new species arose gradually. Punctuated equilibrium model Gradualism

  17. Depicting Relationships • The pattern of how organisms are related through evolutionary descent from a common ancestor is termed phylogeny. • These relationships are depicted in a branching diagram called a cladogram or phylogenetic tree. • The diagram is based on discovering shared advanced characteristics for each branch point. • All the species at a particular branch point share a common ancestor.

  18. Phylogenetic Trees / Cladograms

  19. Question

  20. Molecular clock concept • The number of differences in the proteins of two species might indicate the time that had elapsed since these species diverged from their most recent common ancestor. This is the concept of the molecular clock. Caution with molecular clock data • The molecular clock ‘ticks’ at different rates for different proteins. • The rates of change in the same protein can differ in different groups.

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