BSC2010-evolution-2-2024 (3)
Page 5: Definition of Evolution
Organic/Biological Evolution: The descent of modern organisms with modification from preexisting life-forms.
Examples include: Human, Gorilla, Chimpanzee, Gibbon, Orangutan.
Page 6: Historical Context of Evolution
Ancient Greeks (2500 years ago):
Aristotle: species are “fixed.”
Judeo-Christian beliefs (2000 years ago):
Species do not change; each species is divinely created; Earth is ~6000 years old.
Linnaeus thought evolution was absurd.
Page 7: Confounding Evidence I - Biogeography
Similar species often inhabit the same geographic region.
Different species with similar forms can be found in different regions.
Specific traits adapt to environments, e.g., thick, waxy leaves in desert plants.
Page 8: Confounding Evidence II - Comparative Morphology
Comparative Morphology: Study of similarities and differences in body plans of major groups.
Puzzling patterns:
Similar bone structures in different animals (e.g. humans and dogs).
Some structures are identified as vestigial.
Page 9: Homologous Structures
Examples include:
Human arm
Dog foreleg
Seal flipper
Page 10: Developmental Homology
Both chick and human have gill pouches and tails, indicating shared ancestry.
Page 11: Vestigial Structures
Examples:
backbone
pelvic girdle
coccyx (tailbone)
Small bone attached to pelvic girdle in humans, akin to structures in other mammals.
Page 12: Confounding Evidence III - Geological Discoveries
Georges Cuvier:
Deeper layers contain simpler fossils than shallower layers.
Some fossils seem related to known species; fossils appear/disappear between layers.
James Hutton and Charles Lyell:
Suggested geology changes gradually over time.
Page 13: Darwin and Wallace
Charles Darwin and Alfred Wallace developed similar theories on evolution.
Page 14: Charles Darwin's Voyage
HMS Beagle (1831-1836):
Major journey across various regions, including the Galapagos Islands.
Page 15: Darwin’s Observations in the Galapagos
Observed various lifestyles and body forms; identified 13 species of finches that adapted to environmental challenges.
Page 16: Theory of Natural Selection
Darwin and Wallace co-published their theories in 1858; "The Origin of Species" was published in 1859, introducing natural selection.
Page 17: Darwin’s Facts of Natural Selection
Species can potentially increase in population exponentially.
Actual population sizes tend to remain stable due to limiting resources.
Results in a “struggle for existence.”
Page 18: Continued Darwin’s Facts
Individuals within a species exhibit variation.
Some variations enhance survival and reproduction.
Variations are inheritable.
Page 19: Summary of Darwin’s Theory
Key conclusions of natural selection:
Overproduction and struggle for existence
Heritable individual variation
Final conclusion: Differential reproductive success causes evolution, termed natural selection.
Page 20: Other Points on Darwin’s Theory
Natural selection affects only heritable traits; no inheritance of acquired characteristics as per Lamarck.
Evolution occurs at the population level, suggesting gradual emergence of biodiversity through organism-environment interactions.
Page 21: Darwin’s Later Works
Published "The Descent of Man and Selection in Relation to Sex" in 1871.