Evolution
Gradual change in species over generations through genetic variation and natural selection.
How species change
Species evolve through existing variation, natural selection, and sexual selection.
Darwin and Wallace
Scientists who proposed the theory of evolution by natural selection.
Darwin’s observations
Populations reproduce rapidly, individuals vary, some variation is inherited, and not all offspring survive.
Darwin’s inferences
Variations that help individuals survive and reproduce are more likely to be passed on (adaptations).
Natural selection
Process by which individuals with advantageous traits reproduce more successfully, changing a species over time.
Sexual selection
Type of natural selection where individuals with traits that increase mating success are favored.
Convergent evolution
Different species independently evolve similar traits due to similar environments or pressures.
Homoplasy
Similar traits in unrelated species that evolved due to convergent evolution, not shared ancestry.
Homology
Similar traits due to shared ancestry, even if functions differ (e.g., mammal forelimbs).
Analogy
Traits with similar functions but different evolutionary origins (e.g., wings of bats and insects).
Darwin’s uncertainty
Did not know how traits were inherited or how variation arose.
Mendel’s contribution
Discovered laws of heredity—traits are passed through discrete units (genes).
de Vries’ contribution
Proposed evolution could occur through spontaneous genetic mutations.
Genetic mutation
Random, heritable change in a gene’s DNA sequence that may be harmful, neutral, or beneficial.
Modern evolutionary theory
Combines Darwin’s natural selection with genetics—”Modern Synthesis.”
Advantages of studying other species
Allows comparison, disease research, conservation, and understanding of unique traits.
Ecological niche
The specific environmental role and adaptations of a species in its ecosystem.
Example of convergent evolution
Fish and dolphins have similar fins and body shapes despite different ancestries.
Drosophila (fruit fly) research
Used to study genetic mutations because of fast reproduction and clear traits.
Chromosome
Condensed strand of DNA found in the cell nucleus.
Gene
A segment of DNA that encodes information for a specific protein.
Epigenetics
Study of how gene expression is regulated by factors that don’t change DNA sequence (e.g., methylation).
Human vs animal brain structure
All mammals share basic brain regions, but relative sizes differ by species’ lifestyles.
