Chapter 22: An Introduction to Evolution

A set of practice flashcards covering key concepts, terms, and examples from the Evolution lecture notes.

What is the definition of evolution as used in biology?

Heritable change in one or more characteristics of a population or species from one generation to the next.

What is microevolution?

Changes in a single gene in a population over time.

What is macroevolution?

Formation of new species or groups of species.

What is empirical thought?

Observation-based reasoning; shift in the 1600s toward seeking rational explanations rather than relying on non-physical or spiritual views.

What is the difference between a species and a population?

A species is a group of related organisms capable of interbreeding to produce viable offspring; a population is members of the same species likely to encounter each other and interbreed.

Who contributed to early classification and the modern species concept in the 17th century?

John Ray developed an early classification system and the modern species concept; Carolus Linnaeus extended the modern species concept.

Did John Ray or Carolus Linnaeus propose that evolutionary change promotes the formation of new species?

No. Neither proposed that evolutionary change promotes the formation of new species.

What did Buffon and Lamarck propose about life forms?

That life forms are not fixed; Lamarck proposed inheritance of acquired characteristics (e.g., giraffe necks).

What is uniformitarianism?

Slow geological processes cause substantial change; Earth is much older than 6,000 years.

What did Thomas Malthus argue?

Only a fraction of any population will survive and reproduce due to limited resources, leading to competition.

Who was Charles Darwin and which fields influenced his theory?

A British naturalist born in 1809; his ideas were shaped by geology, economics, and observations from the Voyage of the Beagle.

What did Darwin notice about Galápagos island finches?

Distinctive traits and differences among island finches that provided specialized feeding strategies, with similarities across species but key differences in beak form.

What beak characteristics are associated with ground finches and their diets?

Ground finches have beaks shaped to crush various seed sizes; large beaks crush large seeds, small beaks crush small seeds.

What is a probing beak used for in Galápagos finches?

To search for insects in crevices and then pick them up; some can also probe wood.

What is natural selection?

More offspring produced than can survive; competition for limited resources; individuals with better traits flourish and reproduce.

What is descent with modification?

Evolution based on heritable variation within a species and natural selection, leading to gradual change over generations.

What is convergent evolution?

Unrelated lineages evolve similar traits because they occupy similar environments, not because they are closely related.

What is homology?

Fundamental similarity due to descent from a common ancestor; can be anatomical, developmental, or molecular.

What are vestigial structures?

Anatomical structures with no apparent function but that resemble ancestral structures.

Give two examples of vestigial structures.

Humans: embryonic tail and ear-wiggling muscles; Boa constrictors: skeletal remnants of hip and hind legs.

What is molecular homology?

Similarities at the molecular level (DNA) indicating common ancestry; many pathways are conserved across species.

What is an ortholog?

A homologous gene in separate species that originated by speciation and reflects evolutionary changes.

What is a paralog?

A homologous gene within a single species arising from gene duplication; can form a gene family (e.g., globin genes).

What is horizontal gene transfer?

Exchange of genetic material among different species; common in bacteria and can occur between prokaryotes and eukaryotes.

What does Figure 22.14 illustrate about evolution?

An ancestral gene undergoes mutation accumulation in different lineages, leading to evolutionary separation of organisms (e.g., E. coli vs. C. acetylbutylicum) from a common ancestor.

What is a gene family and what are paralogs?

Two or more paralogs within a genome produced by gene duplication; enables specialized functions over time.

How does chromosome evolution provide evidence for evolution?

Differences in chromosome structure between humans and great apes (e.g., chromosome 2 fused in humans; inversion on chromosome 3 in orangutans) reflect evolutionary relationships.

What is Tiktaalik roseae and why is it important?

A fishapod transitional fossil with a mix of fish and tetrapod features, illustrating the transition from aquatic to terrestrial vertebrates.

What is the evolutionary sequence leading to modern whales?

Whales evolved from terrestrial tetrapods; fossil sequence includes Pakicetus, Ambulocetus, Remingtonocetus, Rodhocetus, Dorudon, leading to modern cetaceans.

Give an example of convergent evolution.

Giant anteater and echidna both have long snouts and tongues for ants, despite not being closely related.

What does biogeography mean by endemism?

Endemic means naturally found only in a particular location (e.g., Island fox on the Channel Islands).

What is notable about Australia’s mammal evolution?

Australia’s isolation led to marsupials being common; no large terrestrial placental mammals are native there.

When was Darwin’s On the Origin of Species published?

1859.

What is the p53 example used to illustrate in molecular evolution?

Comparing amino acid sequences across species shows conserved regions; more similar sequences indicate closer evolutionary relationships.