Unit 5 Evolution Vocabulary

Evolution

The process of biological change in populations over time.

Fossil

The preserved remains, impressions, or traces of ancient organisms from the geologic past.

Biodiversity

The total variety of living organisms in an ecosystem, biome, or across the biosphere.

Common ancestor

An ancestral organism or population from which different descendant species originated.

Deep time

The concept that Earth's history extends over an immense period of time far beyond human memory.

Uniformitarianism

The geological principle that the physical processes shaping Earth today operated in the same manner in the past.

Use and disuse

Lamarck's superseded hypothesis that structures frequently utilized become enhanced, while unused parts deteriorate.

Inheritance of acquired characteristics

Lamarck's superseded concept stating that modifications acquired during an individual's lifetime can be transmitted to offspring.

Artificial selection

Selective breeding by humans to propagate organisms exhibiting desirable hereditary characteristics.

Inherited variation

Natural genetic differences among individuals within a population that can be passed to subsequent generations.

Natural selection

Mechanism of evolution where individuals carrying advantageous heritable traits survive and reproduce at higher rates than others.

Overproduction

The reproductive pattern in which more offspring are generated than the local environment can support.

Struggle for existence

The competition among members of a population for limited resources such as food, living space, and mates.

Differential reproductive success

The disparity in offspring production between individuals with advantageous adaptations and those without them.

Adaptation

Any heritable physical, physiological, or behavioral trait that enhances an organism's ability to survive and reproduce.

Fitness

A measure of how successfully an organism survives and transmits its genes to fertile offspring.

Common descent

The scientific principle that all living and extinct species share ancestral lineages tracing back to shared origins.

Descent with modification

The principle that species change over generations as ancestral lineages accumulate structural and functional changes.

Biogeography

The scientific study of the geographic distribution of living organisms and their extinct ancestors.

Radioactive dating

Method of determining the absolute numerical age of rocks and organic remains through isotopic decay rates.

Fossil record

The total worldwide assembly of preserved ancient remains and traces documenting the history of life on Earth.

Homologous structures

Anatomical features in different species that share an underlying ancestral design despite performing different functions.

Analogous structures

Body parts that share similar functions across species but evolved independently without a common ancestral origin.

Vestigial structures

Inherited anatomical remnants that have lost most or all of their original ancestral utility.

Comparative embryology

The study of structural similarities and divergences observed across organisms during their early developmental stages.

Universal genetic code

The shared molecular triplet codons and nucleotide translation systems utilized by almost all living organisms.

Homologous proteins

Functional polypeptides across different taxa that share amino acid sequence and structural affinities inherited from a common ancestor.

Genotype

The full genetic constitution or combination of specific alleles carried by an organism.

Phenotype

The observable physical, biochemical, and behavioral attributes of an organism shaped by genetic and environmental factors.

Population

A localized group of individuals belonging to the same species that inhabit a shared geographical area and interbreed.

Gene pool

The complete set of all alleles and genes present across all individuals in an interbreeding population.

Allele frequency

The proportion of a specific allele relative to all alternative alleles of that gene locus within a population.

Evolution (genetic definition)

Any shift in the relative allele frequencies of a population's gene pool across successive generations.

Mutation

A permanent change in the nucleotide sequence of DNA that creates new genetic variations.

Genetic recombination

The rearrangement of existing alleles into novel gene combinations during sexual reproduction and meiosis.

Independent assortment

The random alignment and separation of maternal and paternal homologous chromosome pairs during meiosis I.

Crossing over

The reciprocal exchange of genetic segments between non-sister chromatids of homologous chromosomes during prophase I of meiosis.

Lateral gene transfer

The transmission of genetic elements between distinct organisms through mechanisms other than direct vertical descent.

Single-gene trait

A phenotypic characteristic governed by alleles at a single genetic locus.

Polygenic trait

A phenotypic characteristic controlled by the additive effects of two or more independent genes.

Evolutionary fitness

The relative quantitative contribution an individual makes to the gene pool of the next generation.

Evolutionary adaptation

An inherited anatomical, physiological, or behavioral feature that elevates an individual's reproductive success.

Directional selection

A mode of natural selection that favors individuals displaying phenotypes at one extreme of a phenotypic distribution.

Stabilizing selection

A mode of natural selection favoring intermediate phenotypes while acting against both phenotypic extremes.

Disruptive selection

A mode of natural selection favoring both phenotypic extremes over intermediate variants.

Genetic drift

Stochastic fluctuations in population allele frequencies resulting purely from chance occurrences, most prominent in small groups.

Bottleneck effect

A drastic loss of genetic variation resulting from a sudden, severe contraction in population size caused by environmental catastrophes.

Founder effect

The establishment of a new population by a small group of dispersing individuals whose allele frequencies differ from the parent stock.

Genetic equilibrium

A theoretical state in which allele and genotype proportions remain unchanged across generations in the absence of evolutionary influences.

Hardy-Weinberg principle

The mathematical rule stating that allele frequencies in a sexually reproducing population remain static unless external evolutionary forces act upon them.

Gene flow

The transfer of genetic alleles into or out of a population resulting from the movement of fertile individuals or gametes.

Species (biological concept)

A group of populations whose members possess the potential to interbreed in nature and produce viable, fertile offspring.

Speciation

The evolutionary lineage-splitting event that results in the formation of one or more distinct species.

Reproductive isolation

The presence of biological barriers that prevent members of two different species from producing viable, fertile offspring.

Behavioral isolation

Reproductive divergence caused by differences in courtship displays, mating calls, or pheromonal cues between populations.

Geographic isolation

Spatial separation of populations by physical landscape barriers such as mountain ranges, canyons, or water bodies.

Temporal isolation

Reproductive isolation arising when related populations mate or release gametes during different times of day, seasons, or years.

Ecological competition

The interaction between organisms vying for identical limiting environmental resources that can drive divergent specialization.

Gene duplication

A mutational event producing an extra copy of a DNA sequence, frequently caused by unequal homologous crossing over.

Gene family

A cluster of phylogenetically related genes that arose through ancestral gene duplications followed by functional diversification.

Molecular clock

A tool estimating divergence times between lineages by measuring the steady accumulation of neutral mutations over time.

Neutral mutation

A base-pair alteration in a DNA sequence that exerts neither positive nor negative effects on survival or reproductive fitness.

Hox genes

A conserved group of homeotic regulatory genes that direct the anterior-posterior patterning and identity of embryonic body segments.

Ubx gene

A specific homeobox gene responsible for regulating the identity of thoracic and abdominal appendages, such as suppressing abdominal legs in insects.

Binomial nomenclature

The formal two-part Latin naming system developed to assign every organism a standardized genus and specific epithet.

Genus

A Linnaean taxonomic category ranking above species and consisting of structurally and phylogenetically closely related species.

Species identifier

The second word in a scientific binomen that designates a particular species within its designated genus.

Taxon

Any named biological grouping or unit at any level within a formal taxonomic classification hierarchy.

Systematics

The scientific field focused on classifying organisms and reconstructing their evolutionary phylogenetic relationships.

Domain

The highest, most inclusive formal category in biological classification, positioned above kingdoms.

Kingdom

A broad taxonomic rank directly subordinate to domain and divided into phyla.

Phylum

A primary taxonomic division ranking below kingdom and containing related classes.

Class

A taxonomic rank below phylum and above order, grouping related orders.

Order

A taxonomic rank situated between class and family, comprising related biological families.

Family

A taxonomic rank located between order and genus, assembling closely related genera.

Species (taxonomic rank)

The foundational and most specific major category within the Linnaean taxonomic hierarchy.

Phylogeny

The evolutionary lineage history and ancestral relationships among groups of living and extinct organisms.

Phylogenetic systematics

The classification of organisms based explicitly on their evolutionary branching sequences and shared ancestry.

Clade

A monophyletic taxonomic unit consisting of an ancestral taxon and all of its evolutionary descendants.

Monophyletic group

A lineage grouping that includes an ancestral species and all of its descendants, without omissions.

Paraphyletic group

An artificial grouping that encompasses a common ancestor and some, but not all, of its descendant lineages.

Cladistic analysis

A comparative biological method using shared derived characteristics to infer evolutionary branching patterns.

Cladogram

A branching tree diagram that illustrates hypothesized phylogenetic relationships among biological clades.

Root (cladogram)

The basal branch point representing the common ancestor shared by every taxon depicted on the diagram.

Node (cladogram)

A branching junction that denotes the most recent common ancestor of two or more diverging lineages.

Derived character

An evolutionary novelty that arose in the most recent common ancestor of an exclusive lineage and was inherited by its descendants.

Bacteria (domain)

A major domain of unicellular prokaryotes whose cell envelopes typically contain peptidoglycan.

Archaea (domain)

A major domain of unicellular prokaryotes lacking peptidoglycan in their cell walls, often inhabiting extreme environments.

Eukarya

The domain encompassing all organisms whose cells possess membrane-bound nuclei and compartmentalized organelles.

Eubacteria

The true bacterial kingdom comprising prokaryotic organisms possessing peptidoglycan cell walls.

Archaebacteria

The prokaryotic kingdom comprising ancient microorganisms whose cell walls lack peptidoglycan polymers.

Protista

A polyphyletic paraphyletic kingdom grouping primarily unicellular eukaryotic organisms that are not plants, animals, or fungi.

Fungi

A kingdom of heterotrophic eukaryotic organisms possessing chitinous cell walls that absorb predigested nutrients.

Plantae

A kingdom of multicellular autotrophic eukaryotes possessing cellulose-rich cell walls that produce sugars through photosynthesis.

Animalia

A kingdom of multicellular eukaryotic heterotrophs whose cells lack rigid walls and typically exhibit tissue differentiation.

Prokaryote

A unicellular organism lacking a membrane-enclosed nucleus and specialized membrane-bound cytoplasmic organelles.

Eukaryote

An organism consisting of one or more cells containing a membrane-bound nucleus and organized organelles.

Autotroph

An organism capable of synthesizing organic nutritive compounds from inorganic substances using energy from light or chemicals.

Heterotroph

An organism that must obtain carbon and metabolic energy by ingesting or absorbing other organisms or organic matter.

Peptidoglycan

A mesh-like copolymer of amino acids and sugars forming the structural backbone of eubacterial cell walls.