Mechanisms of Evolution Flashcards

Vocabulary flashcards related to the mechanisms of evolution.

Natural Selection

A mechanism of evolution where traits evolve through differential survival and reproduction.

Evolution

Change in allele frequency over time in a population of organisms.

Genetic Drift

Random changes in allele frequency from one generation to the next.

Gene Flow

Transfer of alleles from one population to another, usually involving movement of individuals.

Mutation

Alteration of a gene that gives rise to a new allele.

CatCard

Needed for all exams at the University of Arizona.

Charles Darwin

Proposed the theory of evolution by natural selection.

H.M.S. Beagle

The ship Charles Darwin sailed on for a 5-year survey.

Origin of Species (1859)

Darwin's book where he introduced natural selection.

White Sands Dunes, New Mexico

An example of natural selection with lizards.

Holbrookia maculata

Species of lizard found at White Sands Dunes.

Crypsis

Matching of body coloration to substrate; an adaptation.

Adaptations

Inherited traits favored by natural selection.

Population

Group of potentially interbreeding individuals of the same species in the same geographic area.

Allele Frequency

Proportion of a particular allele in a particular population.

Gene

A unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

Allele

Form (or version/variation) of a gene.

Genotype

Description of the genetic basis of an individual.

Lizard Coloration

Example of variation in a population.

Heritable Variation

Variation that is genetically-based and can be passed down.

Genetic Drift Effect on Large Populations

Little change in Allele Frequency

Genetic Drift Effect on Small Populations

Dramatic change in Allele Frequency

Evolution

Change in heritable characteristics of biological populations over successive generations.

Natural Selection

The process where organisms better adapted to their environment tend to survive and reproduce more than those less adapted.

Mutation

A change in the DNA sequence of an organism.

Gene Flow

The movement of genes from one population to another.

Genetic Drift

A change in the frequency of an existing gene variant in the population due to random chance.

Allele frequency

The rate at which a specific allele appears within a population.

Microevolution

Changes in gene frequencies within a population over time.

Macroevolution

Evolution that occurs at or above the level of species.

Phenotype

The observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Speciation

The process by which new species arise.

Phylogeny

The evolutionary history of a species or group of species.

Taxonomy

The science of classifying organisms.

Binomial Nomenclature

The system of nomenclature in which two terms are used to denote a species of living organism, the first one indicating the genus and the second the specific epithet.

Homologous Structures

Structures in different species that are similar because of common ancestry.

Analogous Structures

Structures that do not have a common evolutionary origin but are similar in function.

Vestigial Structures

A structure in an organism that has lost all or most of its original function in the course of evolution.

Fossil Record

The totality of fossilized artifacts and their placement within the earth’s rock strata.

Radiometric Dating

A method of dating geological or archeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample.

Adaptive Radiation

The diversification of a group of organisms into forms filling different ecological niches.

Convergent Evolution

The independent evolution of similar features in different lineages.

Divergent Evolution

The accumulation of differences between closely related populations within a species, leading to speciation.

Coevolution

The influence of closely associated species on each other in their evolution.

Sexual Selection

Natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.

Artificial Selection

The selective breeding of domesticated plants and animals to encourage the occurrence of desirable trait.s

Founder Effect

The reduced genetic diversity which results when a population is descended from a small number of colonizing ancestors.

Bottleneck Effect

A sharp reduction in the size of a population due to environmental events or human activities.

Hardy-Weinberg Equilibrium

A principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.

Fitness

An organism's ability to survive and reproduce in a particular environment.

Directional Selection

A mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.

Stabilizing Selection

A type of natural selection in which the population mean stabilizes on a particular non-extreme trait value.

Disruptive Selection

A mode of natural selection in which extreme values for a trait are favored over intermediate values.

Allopatric Speciation

Speciation occurs when biological populations of the same species become isolated from each other preventing or interfering with gene flow.

Sympatric Speciation

Speciation that occurs when two groups of the same species live in the same geographic location, but they evolve differently until they can no longer interbreed and are considered different species.

Prezygotic Barriers

A form of reproductive isolation that occurs before the formation of hybrid zygotes.

Postzygotic Barriers

A form of reproductive isolation that occurs after hybrid zygotes have formed.

Hybrid

The offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction.

Endemic Species

Species that are only found in one particular region.

Phylogenetic Tree

A branching diagram showing the evolutionary relationships among various biological species or other entities.

Clade

A group of organisms believed to have evolved from a common ancestor.

Sister Taxa

Groups of organisms that share an immediate common ancestor and are each other's closest relatives.

Basal Taxon

A lineage that diverges early in the history of a group.

Derived Character

A trait that arose in the most recent common ancestor of a particular lineage and was passed along to its descendants.

Shared Ancestral Character

A character that originated in an ancestor of the taxon.

Horizontal Gene Transfer

The transfer of genes between unrelated species.

Prokaryotes

A microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles.

Eukaryotes

Any organism whose cells contain a nucleus and other organelles enclosed within membranes.

Bacteria

A domain of prokaryotic microorganisms characterized by cell walls containing peptidoglycan.

Archaea

A domain of single-celled organisms that lack a cell nucleus or any other membrane-bound organelles, and are genetically distinct from bacteria and eukaryotes.

Protists

A diverse collection of eukaryotic organisms.

Endosymbiosis

A symbiotic relationship in which one organism lives inside the other.

Primary Endosymbiosis

The process by which a eukaryote engulfs another living prokaryote.

Secondary Endosymbiosis

Occurs when a eukaryote engulfs another eukaryote cell that has already undergone primary endosymbiosis.

Multicellularity

The state of being composed of many cells that cooperate to form an integrated organism.

Cellular Specialization

The process by which cells differentiate and perform specific functions within a multicellular organism.

Colonial Organisms

Organisms that are composed of many individual cells that can survive on their own if separated.

Peptidoglycan

A substance forming the cell walls of many bacteria.

Extremophiles

Organisms that thrive in extreme environments.

Methanogens

Microorganisms that produce methane as a metabolic byproduct in anoxic conditions.

Halophiles

Organisms that thrive in high salt concentrations.

Thermophiles

Organisms that thrive in high temperatures.

Acidophiles

Organisms that thrive in acidic environments.

Capsule (Bacteria)

A sticky outer layer that protects the cell.

Endospore

A dormant, tough, and non-reproductive structure produced by some bacteria.

Gram Stain

A staining technique for the preliminary identification of bacteria.

Binary Fission

A method of asexual reproduction in bacteria.

Transformation

The genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings.

Transduction

The process by which foreign DNA is introduced into a cell by a virus or viral vector.

Conjugation

The transfer of genetic material between bacterial cells by direct contact.

Plasmids

A small, circular DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently.

Nitrogen Fixation

The chemical processes by which atmospheric nitrogen is assimilated into organic compounds, especially by certain microorganisms as part of the nitrogen cycle.

Decomposers

Organisms that break down dead or decaying organisms.

Pathogens

Biological agents that cause disease or illness to their host.

Exotoxins

Toxic substances secreted by bacteria and released outside the cell.

Endotoxins

Lipid components of the outer membrane of gram-negative bacteria.

Biofilms

A thin layer of microorganisms adhering to the surface of a structure, which may include bacteria, fungi, protists, and archaea.

Antibiotics

Substances that kill or inhibit the growth of bacteria.

Antibiotic Resistance

The ability of a microorganism to withstand the effects of an antibiotic.

Vector

Organisms that transmit pathogens from one host to another.