Unit 5 - Evolution of Species and Populations

Compare the three domains of life.

Archaea: Prokaryote, unicellular, varied cell walls; Bacteria: Prokaryote, unicellular, peptidoglycan cell wall; Eukarya: Eukaryote, mostly multicellular, varied cell structures.

Distinguish between the subgroups of domain Eukarya.

Protista: mostly unicellular; Fungi: chitin cell wall; Plantae: cellulose cell wall; Animalia: no cell wall, all eukaryotic.

Describe the process and products of natural selection.

Variation, competition, survival of the fittest → leads to adaptations and evolution of populations.

Explain how mutation and sexual reproduction produce genetic variation.

Mutations create new alleles; sexual reproduction shuffles alleles into new combinations.

Define gene pool, population, and microevolution.

Gene pool: all alleles in a population; Population: same species in an area; Microevolution: small changes in allele frequencies over time.

List the five conditions required for Hardy-Weinberg equilibrium.

Large population, random mating, no mutations, no gene flow, no natural selection.

Explain why Hardy-Weinberg is important to natural populations and public health.

Helps detect if evolution is occurring; predicts disease allele frequencies.

Describe the three main causes of evolutionary change.

Natural selection, genetic drift (random), and gene flow (migration).

Define genetic drift and gene flow.

Drift: random changes in alleles (small populations); Flow: migration adds/removes alleles.

Explain bottleneck effect and founder effect.

Bottleneck: drastic population drop; Founder: small group starts a new population.

Explain how genetic bottlenecks threaten survival.

Reduces genetic variation, making species less adaptable.

Why is natural selection the only mechanism that consistently leads to adaptive evolution?

It increases traits that improve survival and reproduction.

Distinguish between stabilizing, directional, and disruptive selection.

Stabilizing: favors average; Directional: favors one extreme; Disruptive: favors both extremes.

Define and compare intrasexual and intersexual selection.

Intrasexual: competition within same sex; Intersexual: mate choice.

How has antibiotic resistance evolved?

Natural selection favors resistant bacteria that survive and reproduce.

How is genetic variation maintained in populations?

Through mutations, sexual reproduction, and heterozygote advantage.

Why can’t natural selection produce perfect traits?

It can only work on existing traits and there are trade-offs.

Distinguish between microevolution and speciation.

Microevolution: small changes within a species; Speciation: formation of new species.

Define the biological species concept and give its advantage/disadvantage.

Species = interbreeding groups; Good for animals; not useful for fossils or asexual organisms.

List 5 prezygotic and 3 postzygotic reproductive barriers.

Prezygotic: habitat, temporal, behavioral, mechanical, gametic; Postzygotic: hybrid sterility, inviability, breakdown.

How can geological processes lead to speciation?

Geographic isolation leads to allopatric speciation.

How do reproductive barriers evolve in isolated populations?

Different selective pressures cause changes that prevent mating.

Explain sympatric speciation with examples.

New species without geographic separation—e.g., polyploidy in plants or behavioral isolation in animals.

How did Darwin’s finches show adaptive radiation?

One species evolved into many with different beaks to match food sources.

How do hybrid zones affect speciation?

Can lead to reinforcement (stronger barriers) or fusion (species merge).

Give examples of reinforcement and fusion in hybrid zones.

Reinforcement: frogs with weak hybrids; Fusion: fish populations merge.

Compare punctuated equilibrium and gradualism.

Punctuated: fast bursts of change; Gradualism: slow, steady change.

What are the goals of taxonomy?

To classify, name, and organize species based on shared traits and ancestry.

List the taxonomic levels from most specific to most general.

Species, Genus, Family, Order, Class, Phylum, Kingdom, Domain.

Distinguish between systematics and taxonomy.

Systematics: study of evolutionary relationships; Taxonomy: naming/classifying.

Compare homologous and analogous structures.

Homologous: same structure, different use (common ancestry); Analogous: different origin, same function.

Describe convergent evolution.

Unrelated species evolve similar traits due to similar environments.

What is a cladogram and what is an outgroup?

Cladogram: diagram of shared traits; Outgroup: least related group for comparison.

What is artificial selection?

Humans select traits to breed.

What is balancing selection?

Natural selection maintains diversity in a population.

What is homology?

Similarity due to shared ancestry.

What do paleontologists study?

Fossils and ancient life.

What is sexual dimorphism?

Differences in traits between males and females.

What is a stratum (strata)?

Layers of sedimentary rock.

Define adaptive radiation.

Rapid speciation from one ancestor into many new forms.

What is the biological species concept?

Defines species by ability to interbreed and produce fertile offspring.

What is the ecological species concept?

Defines species by ecological niche.

What is a hybrid zone?

Where species interbreed and produce hybrids.

What is the morphological species concept?

Defines species by structural traits.

What is the phylogenetic species concept?

Defines species as smallest group with a shared ancestor.

Define punctuated equilibrium.

Fast evolutionary changes with long stable periods.

What is binomial nomenclature?

Two-part scientific name: Genus + species.

What is a clade?

An ancestor and all its descendants.

What is a cladogram?

Diagram showing evolutionary relationships.

What is systematics?

Study of evolution and classification.