Test 3 Bio Objectives: Quantitative Genetics, Population Genetics, and Early Life

Vocabulary practice flashcards covering quantitative traits, population genetics and Hardy-Weinberg equilibrium, evolutionary mechanisms of selection, and early Earth and life transitions.

Quantitative traits

Measurable characteristics that vary continuously and are controlled by multiple genes acting together with environmental factors.

Gene of small effect

A gene where differences in its alleles cause only a small change in the phenotype.

Gene of large effect

A gene where differences in its alleles cause a large or noticeable change in the phenotype.

Polygenic trait

A trait controlled by many different genes, usually genes of small effect, whose effects add together along with environmental influences to create continuous variation.

Standing genetic variation

Genetic differences and existing alleles that already exist within a population upon which natural selection can act when environmental conditions change, without waiting for a new mutation.

Hardy-Weinberg equilibrium (HWE)

A state in which allele and genotype frequencies remain stable from generation to generation at a specific locus because none of the major mechanisms causing evolutionary change are operating strongly.

HWE allele frequency equation

The relationship $p + q = 1$, where $p$ represents the frequency of the dominant allele and $q$ represents the frequency of the recessive allele.

HWE genotype frequency equation

The relationship $p^2 + 2pq + q^2 = 1$, where $p^2$ represents the frequency of the homozygous dominant genotype, $2pq$ represents the heterozygote frequency, and $q^2$ represents the homozygous recessive genotype frequency.

Assumptions of Hardy-Weinberg equilibrium

The five required conditions for equilibrium at a locus: no natural selection, no mutation, no migration/gene flow, a very large population (essentially no genetic drift), and random mating.

Null model (Hardy-Weinberg equilibrium)

A baseline standard used to compare observed real population data against expected genotype counts in order to detect whether evolutionary processes are operating at a locus.

Individual selection

Selection favoring a trait that increases an individual's own reproductive success ("helps me reproduce").

Kin selection

Selection favoring a behavior that increases the reproductive success of genetic relatives, indirectly helping copies of the individual's genes get passed on ("helps my relatives reproduce").

Early Earth atmosphere

An early planetary environment containing gases from volcanic activity, frequent impacts, intense UV radiation, and very little or no free atmospheric oxygen.

RNA world hypothesis

The hypothesis proposing that early life relied heavily on RNA before modern DNA/protein-based systems evolved, because RNA can store genetic information and perform catalytic functions.

Anaerobic metabolism of early organisms

An energy-obtaining metabolic strategy used by earliest life in an environment without free oxygen, relying on chemical reactions as either heterotrophs or chemoautotrophs.