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C. Evolution · Evolution

Evolution: Unit Review

A1.1 A1.3 A1.5 A1.6 A1.8 A1.9 A1.10 A1.11 A1.12 A1.13 A2.1 A2.2 C1.1 C1.2 C2.1 C2.2 C2.3 C2.4 C3.1 C3.2 C3.3 C3.4About 40 minutes
Learning goals
  • I can explain how variation, selection, drift and gene flow change populations.
  • I can describe and evaluate the evidence for evolution.
  • I can explain how new species form and why species go extinct.
  • I can analyse the impacts of artificial selection, resistance and environmental change.

Words to know

evolution
Change in the inherited traits of a population over generations.
natural selection
Individuals with inherited traits better suited to the environment survive and reproduce more.
genetic drift
Random change in allele frequencies, strongest in small populations.
speciation
Formation of a new species, usually after reproductive isolation.
artificial selection
Humans choosing which individuals breed.

Let's review!

In this unit you learned that populations evolve when the frequencies of inherited traits change over generations. Variation comes from mutation, sexual reproduction and gene flow. Natural selection, sexual selection, genetic drift and gene flow change populations; when populations become reproductively isolated, new species form; when environments change too fast, species may go extinct. You examined the evidence (fossils, anatomy, embryology, biogeography, DNA, direct observation), the history of the theory, and its uses and impacts in medicine, farming and conservation.

This review has a few questions from every lesson. Try each one, then press Show answer to check.

How to use this review

Do two or three sections at a time. For explanation questions, use the key words from the lesson (variation, inherited, selection, survive and reproduce, allele frequency). For calculations (percent after selection, half-life, allele frequency, response to selection), write each step. For every question you get wrong, write down why (forgot a term? divided by the wrong total? mixed up two ideas?) and go back to that lesson's examples. Finish with the 10-question quiz.

Percent after selectionsurvivors with trait ÷ ALL survivorsHalf-life datingcount halvings × half-lifeAllele frequencycopies of allele ÷ (2 × individuals)Response to selectionoffspring mean − population meanGenerations in a time spantime ÷ generation timeNext generation (simulation)share of food × population size
The six calculations from this unit. Write the rule first, then substitute your numbers.
Variationmutation, sexual reproductionand gene flowMechanismsnatural and sexual selection,drift, gene flowOutcomesadaptation, new species,extinctionEvidencefossils, anatomy, embryos,biogeography, DNAHistoryLyell, Lamarck, Malthus,Darwin, Wallace, GouldSocietyresistance, breeding,species at risk
The big picture of the unit: variation feeds the mechanisms of evolution, which produce adaptation, new species and extinction; evidence and history support the theory, and society uses and is affected by it.
Just for fun

Evolution in one sentence, as Darwin might tweet it: "Variation + inheritance + more babies than food + lots of time = every living thing you've ever seen." (Darwin never tweeted. He wrote letters. Thousands of them.)

Adaptation, Niche and Mimicry: The Language of Evolution

1

Classify: a black bear hibernating; a porcupine's quills; a wood frog surviving freezing.

2

What is the difference between a habitat and a niche?

3

A harmless hoverfly looks like a wasp. Name the kind of mimicry.

Where Variation Comes From: Mutations and Genetic Variation

1

Which kind of point mutation causes a frameshift?

2

Why can't a mutation in a skin cell be passed to offspring?

3

Name three sources of genetic variation.

Before Darwin: Deep Time, Extinction, Lamarck and Malthus

1

What did Cuvier show, and what did Lyell argue?

2

State Lamarck's mechanism and why it is rejected.

3

A population of 30 doubles every year with no limits. How many after 4 years?

Darwin, Wallace and the Theory of Natural Selection

1

List the steps of natural selection.

2

80 light and 20 dark moths; birds eat 50% of light and 10% of dark. What percent of survivors are dark?

3

Who independently developed the theory with Darwin?

Evidence for Evolution 1: The Fossil Record

1

A sample has 12.5% of its carbon-14 left. How old is it? (half-life 5730 years)

2

State the law of superposition.

3

Why is Tiktaalik important?

Evidence for Evolution 2: Anatomy, Embryos, Biogeography and DNA

1

Are a whale flipper and a bat wing homologous or analogous?

2

Give an example of a vestigial structure.

3

Species P and Q differ at 4 DNA positions; P and R at 18. Which is P's closer relative?

Adaptation in Real Time: Antibiotic and Pesticide Resistance

1

Does an antibiotic cause resistance? Explain.

2

10 000 bacteria, 10 resistant; a drug kills 99% of sensitive and none of the resistant. Percent resistant among survivors?

3

How do resistance genes jump between bacterial species?

Investigation: Simulating Natural and Artificial Selection

1

In the beak simulation, name the independent and dependent variables.

2

Spoons collect 40 items, forks 40, clothespins 20. With 10 birds next generation, how many of each?

3

What is the key difference between natural and artificial selection?

Patterns of Selection: Stabilizing, Directional, Disruptive and Sexual Selection

1

Which type of selection splits a population into two peaks?

2

Bighorn rams with the biggest horns are shot by trophy hunters; average horn size falls. Type of selection?

3

Male moose fighting is which kind of sexual selection?

Chance and Movement: Genetic Drift, Bottlenecks, Founders and Gene Flow

1

40 plants: 10 AA, 20 Aa, 10 aa. Frequency of A?

2

Why does drift matter most in small populations?

3

Northern elephant seals have low genetic variation. Why?

Speciation: How New Species Form

1

State the biological species concept.

2

Mules are sterile. Which barrier is this?

3

Allopatric or sympatric: a new plant species forms by polyploidy in the same field.

Patterns and Pace: Adaptive Radiation, Convergence, Coevolution and Punctuated Equilibrium

1

Darwin's finches are an example of:

2

Sharks and dolphins have similar shapes because of:

3

What did Eldredge and Gould propose?

Extinction and Vulnerable Species: Environmental Change and Natural Selection

1

Over 100 years, how many generations for a species with a 20-year generation time?

2

Give three traits that make a species vulnerable to extinction.

3

What do COSEWIC and SARA do?

Artificial Selection: Breeding Plants and Animals

1

Name two vegetables bred from wild cabbage (Brassica oleracea).

2

Population mean 100 g; chosen parents 130 g; offspring 109 g. Find the response to selection.

3

Who domesticated corn from teosinte?

Weighing Artificial Selection and Biotechnology: Economic and Environmental Costs and Benefits

1

Give one economic advantage and one environmental disadvantage of artificial selection.

2

Why is a genetically uniform crop risky?

3

Which is more reliable: a peer-reviewed article or an anonymous blog? Why?

Check your understanding

Quiz

1.

Which statement best describes evolution?

2.

Which is the only source of brand-new alleles?

3.

Whose idea was inheritance of acquired characteristics?

4.

A fossil has 25% of its carbon-14 left. Half-life 5730 years. Age?

5.

Bird wings and butterfly wings are:

6.

100 beetles: 50 green, 50 brown. Birds eat 60% of brown and 20% of green. Percent green among survivors?

7.

A few individuals start a new isolated population with different allele frequencies by chance. This is:

8.

Two frog species breed in the same pond in different months. This barrier is:

9.

Punctuated equilibrium proposes that:

10.

Which is a disadvantage of artificial selection?

For parents and teachers

How to use the results: each section of this review matches one lesson. Revisit the lesson that matches the kind of mistake:

  • Adaptation types, niche, mimicry, or "individuals evolve" language → Adaptation, Niche and Mimicry: The Language of Evolution.
  • Mutation types, frameshifts, sources of variation, judging sources → Where Variation Comes From: Mutations and Genetic Variation.
  • Mixing up Lyell, Cuvier, Lamarck and Malthus, or geometric vs arithmetic growth → Before Darwin: Deep Time, Extinction, Lamarck and Malthus.
  • Steps of natural selection, or percentages after selection (dividing by the wrong total) → Darwin, Wallace and the Theory of Natural Selection.
  • Superposition, half-life calculations, transitional fossils → Evidence for Evolution 1: The Fossil Record.
  • Homologous vs analogous vs vestigial, embryology, biogeography, counting DNA differences → Evidence for Evolution 2: Anatomy, Embryos, Biogeography and DNA.
  • "The antibiotic caused resistance", plasmids, resistance calculations → Adaptation in Real Time: Antibiotic and Pesticide Resistance.
  • Variables, hypotheses, data tables, graphs, error, natural vs artificial selection → Investigation: Simulating Natural and Artificial Selection.
  • Stabilizing vs directional vs disruptive, sexual selection → Patterns of Selection: Stabilizing, Directional, Disruptive and Sexual Selection.
  • Allele frequency counting, drift, bottleneck vs founder effect, gene flow → Chance and Movement: Genetic Drift, Bottlenecks, Founders and Gene Flow.
  • Species definitions, prezygotic vs postzygotic barriers, allopatric vs sympatric → Speciation: How New Species Form.
  • Adaptive radiation, convergence, coevolution, punctuated equilibrium → Patterns and Pace: Adaptive Radiation, Convergence, Coevolution and Punctuated Equilibrium.
  • Generation-time reasoning, vulnerability factors, COSEWIC vs SARA → Extinction and Vulnerable Species: Environmental Change and Natural Selection.
  • Breeding examples, selection differential and response → Artificial Selection: Breeding Plants and Animals.
  • One-sided analyses of breeding or biotechnology, genetic diversity, source evaluation → Weighing Artificial Selection and Biotechnology: Economic and Environmental Costs and Benefits.

Tip: ask your teen to explain one big idea aloud each day (for example, "Why don't individuals evolve?"). Explaining is the best test of understanding.