Darwinian Evolution & Speciation – Chapter 7 Review

A comprehensive set of question-and-answer flashcards covering key concepts from Darwinian evolution through speciation, including evidence for evolution, mechanisms of microevolution, geologic time scales, reproductive barriers, taxonomy, and phylogenetic trees.

What scientific field studies both the unity and diversity of life on Earth?

Evolutionary biology.

Give the modern biological definition of evolution.

A change in the heritable characteristics of a species (or population) over successive generations.

Which genetic process allows some animal coronaviruses to become zoonotic for humans?

Mutation that alters the viral genome and host specificity.

Name two serious diseases caused by coronaviruses other than COVID-19.

Severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).

In what year did Charles Darwin publish "On the Origin of Species"?

1859.

Which philosopher believed species were fixed and unchanging?

Aristotle.

What was Lamarck’s major misconception about how species change?

He proposed that individuals could acquire traits during their lifetime and pass them to offspring.

Which geologist argued that Earth is ancient and shaped by slow, cumulative processes?

Charles Lyell.

On which islands did Darwin observe finches that helped inspire his theory?

The Galápagos Islands.

State the two key points Darwin made in "Origin of Species".

1) Modern species descend from common ancestors (evolution). 2) Natural selection is the mechanism of evolution.

What Darwinian observation describes the fact that more offspring are born than an environment can support?

Overproduction.

Which observation refers to finite amounts of food, water, and shelter in an ecosystem?

Limited resources.

What conclusion did Darwin draw from overproduction and limited resources?

Competition among individuals for survival and reproduction.

What term describes the naturally occurring differences among individuals in a population?

Variation.

Define natural selection in one sentence.

The differential survival and reproduction of individuals with favorable heritable traits.

Why don’t individuals evolve, according to evolutionary theory?

Evolutionary change is measured as shifts in a population’s gene pool, not in single organisms.

What does artificial selection refer to?

Human-directed breeding for desired traits in plants or animals.

Name the wild ancestor of all modern dog breeds.

The gray wolf (Canis lupus).

Why have some antibiotics become virtually useless since the 1940s?

Bacteria have evolved resistance through natural selection.

Define adaptation in evolutionary terms.

A heritable trait that improves an organism’s ability to survive and reproduce in its environment.

Briefly describe how fossils form.

Organisms die, become buried in sediment, and their hard parts are compressed into rock.

What dating method measures decay of radioactive isotopes to determine fossil age?

Radiometric dating.

Give one example of a transitional fossil mentioned in class.

Fossil whales with small rear legs.

Which continent’s isolation explains the dominance of marsupials there?

Australia.

What type of anatomical features in mammal forelimbs demonstrate common ancestry?

Homologous bone structures.

How does bioinformatics support evolution?

By comparing DNA/protein sequences to show genetic similarity among species.

Define gene pool.

The complete set of alleles for all genes in a population.

What two primary sources create genetic variation in a population?

Mutation and sexual reproduction (recombination/independent assortment).

What is Darwinian fitness?

An individual’s relative contribution of genes to the next generation.

List two common causes of mutations.

DNA replication errors and exposure to mutagens such as radiation or chemicals.

Define genetic drift.

Random changes in allele frequencies due to chance events, especially in small populations.

What is a population bottleneck?

A drastic reduction in population size that randomly alters allele frequencies.

Describe the founder effect.

Genetic drift occurring when a few individuals colonize a new habitat, carrying only a subset of the original gene pool.

What is gene flow?

The movement of alleles between populations through migration.

Define sexual selection.

Natural selection based on traits that enhance mating success.

What is the ultimate source of all new genetic variation?

Mutation.

Approximately how old is Earth?

About 4.5 billion years.

During which geologic era did dinosaurs first appear?

The Mesozoic era (about 230 mya).

How does plate tectonics influence evolution?

It rearranges continents, creating new environments and isolation that drive speciation.

Define macroevolution.

Large-scale evolutionary changes, such as the origin of new species or groups, over long time periods.

Differentiate nonbranching and branching evolution.

Nonbranching: one lineage gradually changes. Branching: one lineage splits into two or more.

What is a mass extinction?

A relatively brief period when a majority of species on Earth die out.

How do background extinctions differ from mass extinctions?

They occur at lower, more constant rates during normal periods.

State the biological species concept.

A species is a population whose members can interbreed in nature and produce fertile offspring.

Give an example of a pre-zygotic reproductive barrier.

Behavioral isolation, such as species-specific mating calls.

What is hybrid weakness, and is it pre- or post-zygotic?

A post-zygotic barrier where hybrid offspring are sterile or less fit.

Define allopatric speciation.

Speciation that occurs when populations are geographically separated.

Define sympatric speciation.

Speciation that occurs within the same geographic area, often via genetic changes like polyploidy.

Contrast gradualism and punctuated equilibrium.

Gradualism: slow, steady accumulation of changes; punctuated equilibrium: long stasis punctuated by rapid speciation bursts.

List the main ranks of the taxonomic hierarchy in order.

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

What two names form an organism’s binomial scientific name?

Genus and species.

Name the three domains of life.

Bacteria, Archaea, and Eukarya.

Which three kingdoms are usually recognized within Eukarya?

Plantae, Fungi, and Animalia (with protists as the remaining group).

What does a phylogenetic tree represent?

A hypothesis of evolutionary relationships among species.

Define clade.

A group consisting of an ancestral species and all its descendants.

On a phylogenetic tree, how do you determine which two species are most closely related?

Find the most recent common ancestor they share.

How can DNA sequencing refine evolutionary trees?

By quantifying genetic similarities to estimate divergence times.

Which microevolutionary mechanism changed vole fur-color ratios after a forest fire?

Genetic drift (bottleneck caused by the fire).

Rodents with fur color matching the environment have higher what?

Evolutionary fitness due to better camouflage and survival.