BIOL 103 Module 1 Flashcards
What are the three major questions evolutionary biology tries to answer?
Unity of life, Diversity of life, and Adaptation.
What does “descent with modification” mean?
Species change over time, sharing common ancestry but accumulating changes.
What is homology?
Similarity due to shared ancestry.
What is convergent evolution?
Similar traits evolving independently in unrelated lineages due to similar environmental pressures.
What does the fossil record provide in understanding evolution?
Evidence of extinct intermediates and support for common ancestry.
What’s the role of DNA in phylogenetic trees?
Highly conserved genes like rRNA allow comparison across all life forms to infer deep evolutionary relationships.
What are the four postulates of natural selection?
- Trait variation
- Fitness differences
- Trait-fitness correlation
- Heritability of traits
What is artificial selection?
Human-driven evolution by selectively breeding individuals with desired traits.
What is the difference between phenotype and genotype?
Phenotype = observable traits; Genotype = genetic makeup.
What are the main sources of genetic variation?
Mutation, gene flow, recombination (via sex).
What’s the difference between new alleles and new genotypes?
Alleles = new sequences via mutation; Genotypes = new combinations via recombination.
What does Hardy-Weinberg equilibrium assume?
No selection, no mutation, no migration, large population size, and random mating.
What does the Hardy-Weinberg equation predict?
Expected genotype frequencies:
p² + 2pq + q² = 1
What is phenotypic variation due to environment?
Trait differences caused by environmental conditions, not genetics (e.g., hydrangea flower color by soil pH).
What is a genetic polymorphism?
Two or more distinct alleles in a population (e.g., blue vs white flowers in Linanthus parryi).
What does continuous variation suggest about genetic architecture?
Trait is likely influenced by many genes (polygenic).
What is genetic drift?
Random changes in allele frequencies due to sampling error in small populations.
What is a founder effect?
Reduced genetic variation when a new population is started by a small number of individuals.
What is a population bottleneck?
A sharp reduction in population size leading to loss of genetic diversity.
How does population size affect genetic drift?
Smaller populations experience stronger drift and lose variation faster.
What is gene flow?
Movement of alleles between populations (e.g., via pollen or migrating individuals).
How does gene flow affect populations?
Increases genetic variation within populations and reduces differences among them.
What was the key takeaway from the fruit fly experiment?
Small populations show rapid loss of alleles due to drift.
What is the relationship between gene flow and conservation?
Promoting gene flow (e.g., habitat corridors) can preserve genetic diversity.
