Evolutionary Biology & Ecology Lecture Glossary Review

These flashcards provide question-and-answer practice for key concepts across cell biology, genetics, population genetics, life-history strategies, phylogenetics, speciation, mutualism, biogeography, and ecology, as covered in the lecture notes.

What does the cell theory state about biological organization?

The cell is the most basic unit of biological organization.

In an experiment where treatments vary naturally, what is this design called?

A comparative experiment.

Which variable responds to changes in another factor during an experiment?

The dependent variable.

What is a testable prediction based on observations of nature called?

A hypothesis.

Which variable is deliberately altered to test its effect on another variable?

The independent variable.

What kind of experiment involves treatments that are actively altered by the researcher?

A manipulative experiment.

Name Mendel’s two key laws of inheritance.

Independent assortment of allele pairs and segregation of homologous alleles.

How is a scientific law generally characterized?

As an observation that occurs repeatedly and without variation.

What does the theory of evolution explain?

How the frequency of inherited characteristics changes in populations across generations.

What are alleles?

Different nucleotide sequences that can occupy a particular gene locus.

Summarize the central dogma of biology.

Information flows from DNA to RNA through transcription and from RNA to protein through translation.

What is a chromosomal mutation?

An accidental change in the arrangement of large DNA segments during replication.

Define a codon.

A sequence of three RNA nucleotides that codes for a specific amino acid.

Why is cytochrome c useful in molecular evolution studies?

Its gene accumulates silent mutations at a predictable rate, acting as a molecular clock.

What mutation involves accidental removal of large DNA segments?

A deletion.

What term describes the accidental addition of extra DNA segments?

Duplication.

In evolutionary biology, how is fitness defined?

As a measure of reproductive success within a population.

What effect does a frameshift mutation have on a gene?

It alters every downstream codon, changing the entire polypeptide sequence.

What is genotype?

The combination of alleles an individual carries at a particular locus.

Differentiate germline from somatic cells.

Germline cells can be passed to offspring; somatic cells cannot.

What are indels?

Point mutations where a single nucleotide is inserted or deleted.

What is a missense mutation?

A point mutation that changes one amino acid in the resulting protein.

How is mutation rate defined?

The expected frequency of mutations at a locus from one generation to the next.

What does a nonsense mutation create?

A premature stop codon.

What is phenotype?

The physical manifestation of a genotype resulting from gene expression.

Explain polymorphic genes.

Genes that have more than one allele in a population.

What is transcription?

Copying DNA into RNA.

Distinguish transition from transversion mutations.

Transition: purine ↔ purine or pyrimidine ↔ pyrimidine; Transversion: purine ↔ pyrimidine.

Define allometric scaling.

Physical constraints that geometry imposes on organism size.

What is an energy budget?

The total energy available for an organism’s physiological functions.

Explain phenotypic plasticity.

The ability of a phenotype to vary in expression depending on environmental conditions.

What does a reaction norm depict?

The pattern of phenotypic responses across an environmental gradient.

Define adaptation in evolutionary terms.

A trait that increases reproductive success.

What selection favors two contrasting phenotypes simultaneously?

Disruptive (diversifying) selection.

Explain the mutation-selection balance concept.

Deleterious alleles persist at predictable rates due to ongoing mutation despite selection against them.

What is pleiotropy?

A single gene influencing multiple phenotypic traits.

How is relative fitness measured?

Frequency of a genotype relative to the most common genotype’s frequency.

What is the selection coefficient (s)?

A measure of the strength of selection acting against a genotype (s = 1 − w).

State the Hardy–Weinberg genotype frequency equation.

p² + 2pq + q² = 1.

What is the purpose of a chi-square test in population genetics?

To determine whether observed genotype frequencies deviate significantly from expected frequencies.

Define allele frequency.

The proportion of a particular allele among all alleles at a locus in a population.

What does a p-value < 0.05 indicate in hypothesis testing?

The result is statistically significant; the null hypothesis is rejected.

Describe genetic drift.

Random changes in allele frequencies due to chance events.

What is gene flow?

Movement of alleles into or out of a population via migration.

How is effective population size (Ne) calculated for unequal sexes?

Ne = 4 Nf Nm / (Nf + Nm).

Explain founder effect.

Random allele frequency changes when a small subset colonizes new territory.

What is inbreeding depression?

Reduced fitness due to loss of heterozygosity in small populations.

Define fixation in genetic drift.

When an allele becomes the only variant at its locus in a population.

What is overdominance?

The tendency for heterozygotes to have higher frequency or fitness than either homozygote.

Differentiate r-selected from K-selected species with respect to population growth.

r-selected: exponential, density-independent growth; K-selected: logistic, density-dependent growth.

What life-history strategy maximizes population growth rate?

The r-selected strategy.

Define inclusive fitness.

An individual’s own reproductive success plus that achieved by its related kin.

Summarize Muller’s ratchet hypothesis.

Asexual populations accumulate deleterious mutations faster than sexual populations.

What does the Red Queen hypothesis predict?

Sexual reproduction gives hosts an advantage in co-evolutionary arms races with parasites.

Explain runaway sexual selection.

Selection favors increasingly extreme mate-choice traits over generations.

What does a life table record?

Survivorship and reproduction for a cohort across age classes.

Define net reproductive rate (R0).

Average number of offspring an individual is expected to produce over its lifetime.

In a phylogenetic tree, what does a node represent?

The most recent common ancestor of diverging lineages.

What principle favors the tree with the fewest evolutionary changes?

Parsimony.

Distinguish monophyletic from paraphyletic groups.

Monophyletic: ancestor and all descendants; Paraphyletic: ancestor and some, but not all, descendants.

What is convergent evolution?

Evolution of similar traits in unrelated lineages due to similar selection pressures.

Define homology.

Similarity due to inheritance from a common ancestor.

What is a homoplasy?

A trait shared for reasons other than common ancestry (e.g., convergence).

What is allopatric speciation?

Speciation caused by geographic isolation between populations.

Define sympatric speciation.

Speciation occurring within the same geographic area due to resource or niche differentiation.

What is a genetic cline?

A gradual change in allele frequencies across an environmental gradient.

Describe reproductive isolation.

The inability of individuals to produce viable, fertile offspring.

What is polyploidization?

Formation of offspring with more than two sets of chromosomes.

Differentiate autopolyploidization from allopolyploidization.

Autopolyploidization arises from self-fertilization; allopolyploidization arises from hybridization of different parents.

Define hybrid vigor (heterosis).

Fitness advantages observed in hybrids compared to parents.

What are Beltian bodies, and who benefits from them?

Energy-rich glands on acacia leaves; ants eat them and in return defend the plant.

What is an obligate mutualism?

A mutualistic interaction where both species depend on each other for reproduction or survival.

Explain Shelford’s Law of Tolerance.

An organism’s performance is limited by environmental factors outside its optimal range.

Define ecological niche.

The range of environmental conditions and resources a species can utilize.

Differentiate fundamental from realized niche.

Fundamental: potential conditions a species could occupy; Realized: conditions it actually occupies.

What is continental drift?

Movement of Earth’s continents across the mantle due to plate tectonics.

Describe adaptive radiation.

Rapid diversification facilitated by novel traits that exploit new ecological niches.

What is eutrophication?

Oxygen depletion in water bodies due to excessive nutrient input and algal blooms.

Define phylogeography.

The study of the geographic distribution of genealogical lineages.

What does competitive exclusion state?

When two species compete for the same resources, one will outcompete and exclude the other.

Explain phylogenetic conservatism.

The tendency of lineages to retain ancestral traits over long evolutionary periods.