Lecture Notes: Genetic Variation and Evolution by Natural Selection

Overview

• Differences in genes and environment lead to variation among individuals.
• Variation over time can result in evolution of new species (natural selection).

Key Concepts

Variation in Populations

• Phenotypes: Observable characteristics influenced by genes and environment.
• Each individual has a unique genome, leading to different phenotypes.
• Identical twins have the same genes but can have different phenotypes due to environmental factors.

Genes and Environment

• Genes: Code for proteins; genome is the complete set of genes in an organism.
• Environmental Factors: Diet, lifestyle, exposure to sunlight, etc., affect phenotypes.
• Most traits are influenced by an interaction of multiple genes and environmental factors.

Genetic Variation

• Mutations: Changes in DNA code that may alter the protein and phenotype.
• Most mutations do not affect phenotype; some can be beneficial or harmful.
• Beneficial mutations increase survival and reproduction, passing on to next generations.

Natural Selection

• Charles Darwin: Introduced the concept of "survival of the fittest."
• Natural selection involves the passing of advantageous traits to offspring.
• Over generations, traits that enhance survival become prevalent in populations.

Evolution

• Evolution occurs through the accumulation of advantageous genetic changes.
• Over time, significant genetic variation can lead to the formation of new species.
• All species evolved from common ancestors, tracing back to simple life forms over 3 billion years ago.

Evidence of Evolution

• Proven through examples such as antibiotic resistance in bacteria and fossil records.

Conclusion

• Evolution by natural selection explains how species adapt and evolve over time.
• Genetic and environmental interactions lead to diverse and changing phenotypes.

Resources

• More videos and educational resources are available at Cognito.org.
• Additional materials include questions, flashcards, and exam-style questions.
• Progress tracking is available for personalized study guidance.