Population Genetics & Speciation – Core Vocabulary

Comprehensive vocabulary flashcards covering population genetics, mutation types, evolutionary mechanisms, and speciation concepts for Chapter 9 exam review.

Population

A group of organisms of the same species living in a defined area at a given time.

Gene Pool

The total set of genes and all their alleles present in a population at one time.

Allele Frequency

The proportion of a specific allele among all allele copies for a gene in a population (value between 0 and 1).

Evolution (Genetic Definition)

A change in allele frequencies in a population’s gene pool over time.

Mutation

A permanent change in the nucleotide sequence of DNA.

Somatic Mutation

A mutation occurring in a body (non-gamete) cell; affects only the individual, not offspring.

Germline Mutation

A mutation occurring in gametes; passed to offspring and contributes to evolution.

Spontaneous Mutation

Naturally occurring DNA-change arising from replication errors; creates new alleles instantly.

Induced Mutation

DNA-change caused by external mutagenic agents such as radiation or chemicals.

Mutagenic Agent

Physical or chemical factor (e.g., X-rays, UV, pesticides) that increases mutation rate.

Beneficial Mutation

A DNA change that increases an organism’s survival or reproductive success.

Detrimental Mutation

A DNA change that decreases an organism’s survival or reproductive success.

Neutral Mutation

A DNA change with no effect on survival or reproduction.

Point Mutation

A small localised change involving one nucleotide in a gene.

Substitution Mutation

Point mutation where one base is replaced by another (silent, missense, or nonsense).

Silent Mutation

Base substitution that does not change the encoded amino acid; protein remains normal.

Missense Mutation

Base substitution that codes for a different amino acid, potentially altering protein function.

Nonsense Mutation

Base substitution that converts a codon to a STOP, prematurely truncating the protein.

Frameshift Mutation

Insertion or deletion of a nucleotide that shifts the reading frame, altering downstream codons.

Block (Chromosome) Mutation

Large-scale alteration affecting a segment containing multiple genes, usually during meiosis.

Chromosomal Abnormality

Mutation involving whole chromosomes or changes in chromosome number, visible in a karyotype.

Karyotype

Pictorial display of chromosomes used to detect size, number, or banding abnormalities.

Aneuploidy

Presence of one extra or one missing chromosome (e.g., 2n+1 or 2n-1).

Polyploidy

Condition of having more than two complete sets of chromosomes; common in plants.

Gene Flow

Movement of alleles between populations via migration, seed/pollen transfer, etc.

Genetic Drift

Random fluctuation of allele frequencies, strongest in small populations.

Bottleneck Effect

Loss of genetic diversity when a population is drastically reduced by a catastrophic event.

Founder Effect

Genetic drift in a new, isolated population founded by a small number of individuals.

Selection Pressure

Environmental factor that differentially influences survival or reproduction of phenotypes.

Natural Selection

Process in which individuals with advantageous alleles survive, reproduce, and pass them on (‘survival of the fittest’).

Antibiotic Resistance

Ability of bacteria to survive and reproduce despite antibiotic presence, often due to mutation.

Plasmid

Small circular DNA molecule in bacteria that can carry antibiotic-resistance genes.

Conjugation

Transfer of genetic material (usually plasmids) between bacteria through direct cell contact.

Speciation

Formation of new species from ancestral species when populations become reproductively isolated.

Reproductive Isolation

Inability of two groups to interbreed successfully, preventing gene flow.

Allopatric Speciation

Speciation due to geographical separation of populations.

Sympatric Speciation

Speciation without geographical separation, often via genetic changes like polyploidy.

Temporal Isolation

Reproductive barrier where populations breed at different times or seasons.

Behavioural Isolation

Reproductive barrier due to differences in mating rituals or signals.

Geographical Isolation

Physical barrier (mountain, ocean) preventing gene flow between populations.

Divergent Evolution

Accumulation of differences leading two or more species to arise from one ancestor.

Adaptive Radiation

Rapid divergent evolution producing many species adapted to different niches.

Antigenic Drift

Gradual accumulation of point mutations in viral genes, altering surface antigens and causing epidemics.

Antigenic Shift

Abrupt reassortment of viral RNA segments when multiple viruses infect one cell, creating novel strains.

Selective Breeding

Human-directed mating of organisms with desirable traits to enhance those traits in offspring.

Variation (Genetic)

Differences in alleles and traits among individuals of a population.

Fitness (Biological)

An individual’s ability to survive and reproduce in its environment relative to others.

Mutagen

Any agent that increases the frequency of mutations in organisms.

Viable Offspring

Progeny that are capable of living and developing normally.

Fertile Offspring

Progeny that can reproduce successfully, maintaining the species lineage.