Lecture on Biological Evolution

Introduction to Evolution

Evolution is often misunderstood in media and games.
In biology, individuals do not evolve during their lifespan.
Common misconceptions include:
- "Theory" in science vs casual conversation.
- "Fitness" in biology refers to the number of offspring (gene transmission), not physical strength.
- "Evolution" doesn’t always mean increasing complexity.

Biological Evolution: Change in a population's inherited traits over generations.
- Population: A group of organisms of the same species with genetic variety.
- Evolution occurs through changes in the gene pool of a population.

Gene Flow:
- Movement of genes between populations, often through migration.
Mutations:
- Changes in genetic material, can be beneficial, harmful, or neutral.
Genetic Drift:
- Changes due to random events, e.g., a lawn mower affecting grasshopper population.
Natural Selection:
- Traits that improve survival and reproduction are more likely to be passed on.
- Example: Green grasshoppers better camouflaged, thus surviving predators.

Molecular Homologies:
- DNA and proteins demonstrate relatedness among species.
Anatomical Homologies:
- Homologous structures: Similarities due to common ancestry (e.g., human arm and dog forelimb)
- Analogous structures: Similar function, different ancestry (e.g., bird wing and insect wing).
- Vestigial Structures: Inherited but lost original function (e.g., chicken wing claw).
Developmental Homology:
- Similar embryonic stages can indicate shared ancestry.
- Example: Chordata phylum members have notochord during development.

Study of organism distribution across the planet.
Geographic distribution supports evolutionary history.
Example: Marsupials in Australia and South America share ancestry due to continental drift.

Stay curious and keep exploring the wonders of evolution.