Evidence of Evolution | Jamb Biology

Fossil Records as Evidence

1. Definition of Fossils: Remains or traces of ancient organisms preserved in rocks.
2. Fossil Records: Provide a timeline of evolutionary changes across different geological periods.
3. Transitional Fossils: Show intermediate forms between ancient and modern species (e.g., Archaeopteryx links birds and reptiles).
4. Chronological Order: Fossils in deeper layers are older, showing simpler organisms evolving into complex forms.
5. Extinct Species: Fossil evidence of organisms no longer existing today supports evolutionary changes.
6. Human Evolution: Fossils like Australopithecus and Homo erectus trace human ancestry.
7. Plant Fossils: Fossilized pollen and leaves indicate the progression of plant evolution.
8. Geographical Distribution: Fossils of similar species found on different continents suggest continental drift and evolution.
9. Radiometric Dating: Determines the age of fossils using isotopes like carbon-14.
10. Patterns of Evolution: Fossil evidence shows trends like adaptive radiation and extinction events.
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11. Evidence for Gradual Changes: Fossils demonstrate slow, progressive changes in species over millions of years.
12. Example: The horse's fossil record shows gradual changes from small, multi-toed ancestors to modern single-toed horses.
13. Gaps in Fossil Records: Despite missing links, fossil evidence strongly supports evolutionary theory.
14. Marine Fossils: Show that life began in the oceans and diversified onto land.
15. Microfossils: Provide insights into the early forms of life, such as bacteria and single-celled organisms.
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Comparative Anatomy and Physiology

16. Homologous Structures: Similar structures with different functions (e.g., forelimbs of humans, bats, and whales).
17. Evidence of Common Ancestry: Homologous structures suggest a shared evolutionary origin.
18. Analogous Structures: Different structures with similar functions (e.g., wings of birds and insects).
19. Convergent Evolution: Analogous structures arise due to similar environmental pressures, not common ancestry.
20. Vestigial Organs: Structures with no apparent function (e.g., human appendix, whale pelvic bones).
21. Significance of Vestigial Organs: Indicate evolutionary remnants of once-functional traits.
22. Comparative Physiology: Similar biochemical processes (e.g., respiration and metabolism) across species support evolution.
23. DNA Similarities: Genetic codes are nearly universal, indicating common ancestry.
24. Protein Comparisons: Similarities in proteins like hemoglobin demonstrate evolutionary relationships.
25. Examples of Physiology: Enzyme functions and hormonal systems show common evolutionary origins.
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Embryology as Evidence

26. Definition: The study of embryos and their development stages.
27. Embryonic Similarities: Early embryos of different species appear strikingly similar.
28. Example: Fish, birds, and mammals all have gill slits and tails during early embryonic stages.
29. Recapitulation Theory: "Ontogeny recapitulates phylogeny" suggests embryonic development mirrors evolutionary history.
30. Homologous Embryos: Similar developmental patterns indicate a common ancestor.
31. Vestigial Features in Embryos: Traits like gill slits in human embryos highlight evolutionary links to aquatic ancestors.
32. Study of Development: Shows how complex organisms evolved from simpler ancestors.
33. Evolutionary Trends: Embryology highlights gradual complexity in development over time.
34. Examples: Tadpoles resemble fish, reflecting amphibians’ evolutionary transition from aquatic to terrestrial life.
35. Molecular Embryology: Reveals similarities in genes controlling development (e.g., Hox genes).
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Modern Evidence from Genetics and Mutation

36. DNA Evidence: Genetic sequences reveal evolutionary relationships among species.
37. Common Genes: Humans share over 98% of their DNA with chimpanzees, indicating a close evolutionary link.
38. Mitochondrial DNA: Used to trace maternal lineages and evolutionary history.
39. Mutations: Random changes in DNA provide raw material for evolution.
40. Role of Mutations: Introduce genetic variation, leading to new traits and adaptations.
41. Natural Selection and Mutations: Beneficial mutations are passed on, driving evolution.
42. Genetic Drift: Random changes in gene frequencies influence small populations.
43. Genetic Evidence in Human Evolution: Traces migration patterns and interbreeding with species like Neanderthals.
44. Horizontal Gene Transfer: Genetic exchange between organisms (e.g., bacteria) shows non-linear evolutionary patterns.
45. Molecular Clocks: Estimate the time of divergence between species using mutation rates.
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Evolutionary Trends in Plants and Animals

46. Plant Evolution: Transition from simple algae to complex flowering plants.
47. Examples of Plant Trends: Development of vascular tissue, seeds, and flowers.
48. Animal Evolution: From single-celled organisms to multicellular species with complex systems.
49. Examples of Animal Trends: Development of vertebrates, limbs for movement, and specialized organs.
50. Adaptive Radiation: Species diversify to exploit different ecological niches (e.g., Darwin’s finches).