HIV, Evolution, and Natural Selection – Lecture Vocabulary

Vocabulary flashcards covering HIV treatment, mechanisms of evolution, types of natural selection, evidence and hypotheses of evolution, and reproductive isolation concepts.

AIDS

A chronic, life-threatening condition that develops when infection with HIV severely damages the immune system.

HIV (Human Immunodeficiency Virus)

A sexually transmitted virus that attacks CD4 T cells and weakens the immune system, potentially leading to AIDS.

Antiretroviral Therapy (ART)

Medication regimen using multiple antiretroviral drugs to control HIV replication; recommended for all HIV-positive individuals.

Highly Active Antiretroviral Therapy (HAART)

Another name for combination ART using three or more drugs from at least two classes to prevent drug-resistant HIV strains.

Combination Therapy ("the cocktail")

Treatment strategy in which three or more antiretroviral drugs are taken together for maximum HIV suppression.

Natural Selection

Differential survival and reproduction of individuals in a population due to environmental pressures; leads to adaptation.

Evolution

A change in allele frequency in a population over successive generations.

Allele Frequency

Proportion of a specific allele among all allele copies in a population’s gene pool.

Population

A group of organisms of the same species living in the same geographic area and interbreeding.

Species

A group of individuals that actually or potentially interbreed in nature and produce fertile offspring.

Gene Pool

The total collection of alleles present in all individuals of a population.

Gene Flow

Movement of alleles between populations through migration and interbreeding.

Genetic Drift

Random changes in allele frequencies from one generation to the next, especially in small populations.

Mutation

A heritable change in DNA sequence; the ultimate source of new genetic variation.

Adaptation

A heritable trait that increases an individual’s fitness in a specific environment.

Relative Fitness

The reproductive success of one genotype compared with others in the same population.

Directional Selection

Natural selection that favors one extreme phenotype, shifting the population’s trait distribution.

Stabilizing Selection

Selection that favors intermediate phenotypes over extremes, narrowing trait variation.

Diversifying (Disruptive) Selection

Selection that favors extreme phenotypes at both ends of the range over intermediate forms.

Differential Survival and Reproduction

Core mechanism of natural selection; individuals with advantageous traits leave more offspring.

Environmental Pressure

Any factor in an organism’s surroundings that influences its survival and reproduction.

Common Descent

Hypothesis that all living species share a common ancestor and diverged over time.

Static Model

Hypothesis that species arise separately and remain unchanged through time.

Transformation Hypothesis

Idea that species arise separately but change over time in response to the environment.

Separate Types Hypothesis

Proposal that lineages change and new species arise, but major groups originate from separate ancestors.

Fossil Record

Chronological collection of preserved remains used to study evolutionary changes through time.

Phylogenetic Tree

Diagram depicting evolutionary relationships and common ancestry among species.

Comparative Anatomy

Study of similarities and differences in the structures of different species to infer evolutionary relationships.

Homology

Similarity in characteristics resulting from common ancestry.

Vestigial Structure

A non-functional or reduced feature that was functional in an ancestor.

Biogeography

Study of the geographic distribution of species and how it relates to evolutionary history.

Convergent Evolution

Independent evolution of similar adaptations in distantly related species facing similar environmental challenges.

Radiometric Dating

Technique for estimating the age of rocks and fossils by measuring decay products of radioactive elements.

Reproductive Isolation

Condition in which different species cannot interbreed or produce fertile offspring, maintaining separate gene pools.

Pre-fertilization Barrier

Reproductive isolation mechanism that prevents mating or fertilization between species.

Post-fertilization Barrier

Isolation mechanism that reduces viability or fertility of hybrid offspring after mating occurs.

Spatial Isolation

Pre-fertilization barrier caused by non-overlapping habitats of two species.

Behavioral Isolation

Barrier arising from differences in mating behaviors or courtship signals.

Mechanical Isolation

Reproductive barrier in which physical incompatibility of reproductive organs prevents mating.

Temporal Isolation

Barrier where species breed at different times, preventing interbreeding.

Gamete Incompatibility

Pre-fertilization barrier where sperm cannot fertilize eggs of another species.

Interspecies Hybrid

Offspring produced by parents of two different species; often inviable or infertile.

Speciation

Genetic divergence leading to reproductive isolation and formation of new species.

Allopatric Speciation

Speciation that occurs when populations are geographically separated by a physical barrier or distance.

Sympatric Speciation

Speciation that occurs without geographic separation, often through genetic or behavioral divergence.

Founder Hypothesis (Founder Effect)

Genetic drift occurring when a few individuals start a new population with reduced genetic diversity.

Population Bottleneck

Sharp reduction in population size followed by expansion, often lowering genetic diversity.

Fitness (in Evolution)

An individual’s ability to survive and reproduce, passing genes to the next generation.

HMS Beagle Voyage

Darwin’s journey (1831-1836) during which observations of geology and biodiversity led to his natural selection theory.

Environmental Adaptation

Adjustment of a population’s traits to improve survival in a particular environment.

Antibiotic Resistance

Ability of bacteria to survive and reproduce in the presence of antibiotic drugs, often a result of natural selection.