Evolution and Speciation Lecture Review

A comprehensive set of flashcards covering the definitions, history, mechanisms, evidence, and common misconceptions of evolution and speciation.

What is the specific definition of evolution within a population?

Evolution is the process of genetic changes, specifically changes in allele frequencies, within a population through time.

According to George Gaylord Simpson, what distinction must be stressed regarding evolution?

The distinction between the fact that evolution has occurred and the Darwinian theory as to how it occurred.

Who stated that 'Nothing in biology makes sense except in the light of evolution'?

Theodosius Dobzhansky

What were the two primary contributions of Georges-Louis Buffon?

He noted environmental influence on animal form and estimated the earth's age to be ${70,000}$ years.

What was the core argument of Thomas Malthus in 'An Essay on the Principles of Population' (${1798}$)?

Populations grow exponentially until they are limited by resources.

Which scientist proposed the first hypothesis for evolution in ${1809}$?

Jean Baptiste de Lamarck

What mechanism did Lamarck propose for evolution?

The inheritance of acquired traits.

What did Charles Lyell argue in his ${1833}$ work 'Principles of Geology'?

Gradual geologic processes shaped the earth over millions of years.

Which two individuals independently developed the theory of evolution by natural selection?

Charles Darwin and Alfred Russell Wallace

What was the name of the ship and the duration of the expedition Charles Darwin took around the world?

HMS Beagle, from ${1831-1836}$.

What locations did Alfred Russell Wallace explore during his expeditions?

The Amazon rain forest (${1848-1852}$) and the Malay Archipelago (${1854-1862}$).

What were two key observations made by Darwin while developing his theory?

Island species resembled the nearest mainland species, and fossilized species resembled the extant species of each region.

Who sent Darwin a letter in ${1858}$ proposing a nearly identical mechanism for evolution?

Alfred Russell Wallace

What are the two major requirements for adaptation and speciation via natural selection?

Variation in heritable traits and the overproduction of offspring.

What is the 'Modern Synthesis'?

The combination of Gregor Mendel's patterns of inheritance, the relationship between DNA and proteins, and natural selection, including predictive equations.

What is the ultimate source of heritable variation?

DNA mutation.

Does the environment produce favorable mutations?

No, the environment acts on available variation already present within populations.

Does natural selection act on genotypes or phenotypes?

Natural selection acts on phenotypes.

In what way does sexual reproduction contribute to genetic variation?

Through the formation of genetically unique gametes and the combining of gametes at fertilization.

At what biological level does evolution occur?

Evolution occurs in populations over time, not in individuals.

What are adaptations?

Adaptations are the products of natural selection.

What are two examples of 'Natural Selection in Action' mentioned in the notes?

Pesticide resistance in insect populations and artificial selection (e.g., fancy pigeons, livestock).

What are the three primary ways natural selection can alter populations?

Stabilizing Selection, Directional Selection, and Disruptive Selection.

What is sexual selection and what common outcome does it have?

It is the process where individuals with certain traits are more likely to reproduce; it often results in sexual dimorphism.

Besides natural selection, what are three other mechanisms of evolution?

Mutation, Genetic Drift, and Gene Flow.

Which mechanism involves chance changes in small populations due to random events like floods or fire?

Genetic Drift.

What is the difference between the bottleneck effect and the founder effect?

The Bottleneck effect occurs when a population size is drastically reduced by an event, while the Founder effect occurs when a small group starts a new population.

What causes gene flow?

Migration, dispersal, or the removal of barriers.

Name the intermediate fossil forms of the horse mentioned in the evidence of evolution.

Eohippus (${55-45}$ million years ago), Mesohippus (${40-30}$ million years ago), and Hipparion (${23-2}$ million years ago).

What is the difference between homologous and vestigial structures?

Homologous structures are similar due to common ancestry; vestigial structures are remnants that have lost their original function.

What results in analogous traits?

Convergent evolution, where similar selective pressures produce similar traits in species without a common ancestor.

What example is used to illustrate biogeography in the notes?

The geographic distribution of True Toads (Bufonidae) relative to continental drift.

What specific molecular evidence supports the 'unity of life'?

A common genetic code and the similarity of DNA sequences.

Which researchers documented evolution in Galapagos finches from ${1976}$ to present?

Rosemary and Peter Grant

According to the lecture, what are the three criteria for a species?

It is the result of common ancestry, forms a reproductive community (gene flow), and shares a similar ecological niche.

What is the focus of the Biological Species Concept?

A group of populations whose members can interbreed and produce viable offspring.

Which species concept is used to name most of the ${2}$ million+ species discovered to date?

The Morphological Species Concept (based on physical traits).

How does the Phylogenetic Species Concept define a species?

The smallest group that shares common ancestry and forms a branch on a phylogenetic tree.

What is speciation?

The formation of two (or more) species from one ancestral species via a series of splitting events.

What is the difference between prezygotic and postzygotic barriers?

Prezygotic barriers prevent fertilization (e.g., habitat or behavioral differences); postzygotic barriers occur after fertilization (e.g., reduced hybrid viability or fertility).

What is Allopatric Speciation?

Speciation resulting from the geographic separation of members of a parent species through dispersal or vicariance.

Provide an example of vicariance.

The splitting of a population by a geographic barrier like the Grand Canyon.

What is Sympatric Speciation?

Speciation occurring without physical barriers, often through chromosomal errors or behavioral isolation.

What are the two chromosomal errors mentioned under sympatric speciation?

Autopolyploidy (two sets of chromosomes from one species) and Alloploidy (matings between two species).

What is adaptive radiation?

Multiple speciation events resulting from adaptations to available niches, common on island chains or after mass extinctions.

Why is the phrase 'just a theory' a misconception in science?

In science, 'theory' is a well-substantiated explanation, not the common vernacular meaning of a mere guess.

Why is the statement 'individuals evolve' incorrect?

Evolution only applies to heritable traits across generations within a population; individuals do not change their genetic makeup.

Does evolution explain the origin of life?

No, evolution explains how life changes over time, but the origin of life is covered by different hypotheses.

Explain the misconception 'Humans evolved from apes'.

Humans and apes share a distant common ancestry; humans did not descend directly from modern apes.

Is mutation random or purposeful?

Mutation is random and can be deleterious, neutral, or advantageous; organisms do not evolve in purposeful response to the environment.