1. Evidence of Evolution

2. I. Evolution
Evolution: gradual changes in a species over time

3. Jean Baptiste de Lamarck
1. First to propose that living things had descended from a similar extinct species
a. Acquired traits passed on to offspring

4. 2. Acquired Trait: a trait not determined by genes
2. Acquired Trait: a trait not determined by genes. Arises during an organisms lifetime due to their experience or behavior
3. Genetic Trait: a trait determined by genes

5. Charles Darwin: “Father of Evolution”

6. 1. Studied organisms (finches, tortoises, iguanas) on the Galapagos islands.

7. 2. Wrote the “Origin of Species”

8. 3. Evolution occurs due to natural selection

9. Natural Selection: Organisms that are better adapted to their environment will have a better chance of survival, therefore they will reproduce more

10. E. Steps to Natural Selection

11. Variation is necessary for natural selection
a. Within a population there is a variation in traits (phenotypes)

12. Living things face a constant struggle for existence
a. Produce more offspring than there is room and food for, so they must compete to survive

16. Only some individuals survive and reproduce
a. Some individuals are more “fit” for the environment or for life in general
ex. Resistance to disease

18. 4. Each generation consists of individuals with traits(phenotypes) that made them more “fit”, so over time, alleles for those traits will increase in frequency

19. Species adapt to their environment
a. selection tends to make organisms better suited to their environment

20. C. Lethal genes are kept in the gene pool if in the heterozygous form because those individuals will not show the lethal phenotype

21. Evidence of evolution: how do we know it occurs
1. Similarities in Embryology: during early stages of development, organisms that descend from common ancestor look the same

23. 2. Homologous features: similar features that originated in a shared ancestor
ex. Forelimbs of vertebrates

24. 3. Analogous Features(not a piece of evidence for evolution): serve similar function and they look similar, but the organisms don’t share a common ancestor
ex. Wings in insects and birds

25. 4. Vestigial Features: features that are apparently useless to the modern organism, but may have been useful to ancestors
ex. Tailbone in humans, pelvic bones in whales

26. 5. Similarities in DNA and macromolecules(proteins, carbs, etc.)

27. Patterns of Evolution:
1. Coevolution: change of two or more species in close association with each other.
ex. Hummingbirds and the flowers they feed on

28. 2. Convergent Evolution: organisms that are not closely related evolve to show similar trait
ex. Sharks and Dolphins

29. Divergent evolution: two or more organisms evolve to become more and more dissimilar

30. a. Adaptive Radiation: many related species evolve from a single ancestral species

31. b. Artificial Selection: speeding up of divergent evolution
ex. Dog breeding