This lecture introduces the concept of evolution, focusing on mechanisms like natural selection, convergent evolution, divergent evolution, and coevolution, as well as key examples.
Basics of Evolution
Evolution means organisms change over many generations.
These changes may help organisms survive or lead to their extinction.
Natural Selection
Natural selection favors traits that help organisms survive and reproduce.
Traits that are not helpful for survival can lead to extinction.
Charles Darwin established the basis for natural selection through his research, especially in the Galapagos Islands.
Convergent Evolution
Convergent evolution occurs when different species develop similar traits independently.
Similar solutions to survival challenges can appear in unrelated species due to similar environmental pressures.
Example: Both cacti (plants) and porcupines (animals) evolve spines as protection, though they are unrelated.
Divergent Evolution
Divergent evolution happens when related species evolve different traits over time.
Starting from a common ancestor, species adapt to different environments, leading to unique characteristics.
Example: Bird beaks change shape across species depending on their food sources.
Coevolution
Coevolution is the process where two species evolve in response to each other's changes.
These species usually rely on each other for survival.
Example: Certain orchids and their pollinating insects have closely linked evolutionary paths.
Key Terms & Definitions
Evolution — gradual change in species over generations.
Natural Selection — process where traits beneficial for survival become more common.
Convergent Evolution — unrelated species independently develop similar traits.
Divergent Evolution — related species evolve different traits from a common starting point.
Coevolution — two species evolve in response to each other's adaptations.
Action Items / Next Steps
Study the examples of different types of evolution.