Charles Darwin's Voyage and Theory
Left on a 5-year voyage in December 1831.
Spent 20 years developing the theory of evolution by natural selection.
Published "On The Origin of Species."
Natural Selection Principles
Natural Selection: Nature favors some individuals’ reproductive success over others.
Result of natural selection leads to evolution over generations.
Key Observations
Individuals in populations compete for limited resources.
Populations produce more offspring than adults, leading to competition.
Some individuals inherit advantageous traits for survival and reproduction.
Variations within populations are heritable.
Inferences About Populations
Populations change over time as advantageous traits become common.
Survival of the fittest refers to reproductive fitness, not physical fitness.
Example: Large-billed Ground Finch
Evolved from an ancestral species with smaller bills.
Limited resources led to competition among finches with different bill sizes.
Finches with larger bills had better access to abundant larger seeds, leading to higher survival and reproduction rates.
Scientific Theory Characteristics
Supported by extensive evidence and remains open for revision.
No amphibians or large mammals on remote islands; fossil complexity supports evolution.
All studied organisms exhibit homologous and vestigial features.
Importance of Predictions
Predictions from natural selection help anticipate species' changes due to climate change and antibiotic resistance.
Concluding Thoughts
Evolution occurs under selective pressures (e.g., food scarcity, temperature changes).
Organisms with greater fitness adapt over generations, potentially leading to new species.
Selective pressure can be abiotic (non-living) or biotic (living).