Glossary

Adaptation | A trait that has evolved through natural selection, providing a functional advantage in a particular environment​

Adaptive Evolution | Evolution that results in organisms being better suited to their environment due to the advantageous traits passed on through natural selection​

Adaptive Radiation | The diversification of a group of organisms into different species, each adapted to a specific environment or niche.

Allele Frequency | The relative frequency of an allele (gene variant) in a population.

Allopatric Speciation | The process of speciation that occurs when a population becomes geographically isolated and evolves into a new species.

Allopolyploidy | A form of polyploidy that occurs when two different species interbreed and produce viable, fertile offspring with extra sets of chromosomes.

Anagenesis | Evolutionary change within a single lineage without branching

Analogous Structures | Features that serve similar functions in different species but do not share a common ancestry

Anthropogenic | Refers to human-induced changes or impacts on the environment.

Apomorphy | A derived or new trait that evolved in a particular lineage and is not present in the lineage's ancestral form; distinguishes members of a clade from their common ancestors and is a key characteristic used in phylogenetic analysis to define evolutionary relationships between species

Aposematic | Organism that expresses warning signals (e.g. coloration) to indicate toxicity or danger

Asexual Reproduction | A mode of reproduction where offspring arise from a single organism, inheriting the genes of that parent only.

Autopolyploidy | A form of polyploidy where an individual has multiple sets of chromosomes from the same species.

Background Extinction Rate | The normal rate at which species go extinct due to natural causes.

Binomial Nomenclature | The two-part scientific naming system for organisms, consisting of the genus and species name

Biodiversity | The variety of life forms in an ecosystem, including species diversity.

Biological Species Concept | A definition of species as a group of individuals that interbreed and produce fertile, viable offspring. It distinguishes species based on their ability to reproduce successfully.

Branch (of a phylogenetic tree) | The evolutionary lineage or path between two nodes on a phylogenetic tree; indicates the divergence of species or groups from a common ancestor

Clade | A group of organisms that includes a common ancestor and all its descendants

Cladogenesis | The process by which a species splits into two or more distinct species

Convergent Evolution | A process where unrelated species evolve similar traits due to similar environmental pressures.

Derived Character | A trait that appears in a recent ancestor and is unique to a particular clade

Descent with Modification | Darwin's concept that all life is related to one another, and that species evolve over time, with changes accumulating across generations, leading to a divergence from common ancestors

Dispersal | The movement of individuals of a species to new geographic areas, which can lead to allopatric speciation.

Ecology | Study of interactions between organisms and their environment

Evolution | The process through which populations of organisms change over generations due to alterations in genetic composition

Extinction | The process by which a species, genus, or family ceases to exist.

Founder Species | The original species from which other species evolve in adaptive radiation.

Gene Pool | The complete set of genetic information, including all the gene variants, in a population or species.

Habitat Isolation | A form of reproductive isolation where species occupy different habitats, reducing the likelihood of mating.

Homologous Structures | Anatomical features that are similar in different species due to shared ancestry

Horizontal Gene Transfer | Movement of genetic material between organisms other than by the transmission of DNA from parent to offspring

Hybrid | An organism resulting from the mating of two different species, typically infertile due to genetic incompatibility.

Mass Extinction | A rapid event leading to the loss of a large number of species across multiple environments.

Maximum Likelihood | A statistical method used to estimate the probability of a particular phylogenetic tree being correct

Molecular Systematics | The use of molecular data to determine evolutionary relationships

Monophyletic Group | A group consisting of a common ancestor and all its descendants

Morphological Species Concept | A species concept that defines species based on their physical characteristics (morphology).

Mutualism | Interaction in which both species benefit

Natural Selection | A mechanism of evolution where individuals with traits that enhance survival and reproduction are more likely to pass on their traits to the next generation. It is sometimes called "survival of the fittest"

Niche | All the biotic and abiotic factors required for the survival and persistence of a species; the role and position a species has in its environment

Node (of a phylogenetic tree) | A point on a phylogenetic tree representing the common ancestor of descendant groups

Outgroup | A species or group that is closely related to but not part of the group being studied, used to infer the root of a phylogenetic tree

Parsimony | The principle that the simplest explanation, requiring the fewest evolutionary changes, is preferred

Phylogeny | A diagram showing evolutionary relationships among species, often resembling a branching tree.

Plesiomorphy | An ancestral trait that is inherited from a distant common ancestor and is shared by multiple species or groups; often present in both the ancestral and descendant groups, making them less useful for distinguishing relationships in a specific clade

Polyphyletic Group | A group of organisms that does not include the most recent common ancestor; a group of organisms that does not share an ancestor exclusive only to that group

Polyploidy | A condition in which an organism has extra sets of chromosomes, which can lead to speciation, especially in plants.

Polytomy | A section of a phylogenetic tree where a single ancestor splits into more than two descendant species

Postzygotic Barrier | A reproductive barrier that occurs after fertilization, preventing the offspring from developing into fertile, viable adults.

Predation | Interaction where one organism consumes another

Prezygotic Barrier | A mechanism that prevents fertilization from occurring, thus preventing species from reproducing.

Reproductive Isolation | A state where different species or populations are unable to interbreed successfully, leading to speciation.

Root (of a phylogenetic tree) | The base of a phylogenetic tree, representing the most recent common ancestor of all taxa in the tree

Selective Pressure | External factors that influence which traits are advantageous and therefore passed on, such as predation, food availability, or climate

Sexual Reproduction | The process where two organisms contribute genetic information (through gametes like sperm and egg) to produce offspring, allowing for genetic diversity.

Sister Taxa | Two descendants that split from the same node in a phylogenetic tree

Species | A group of individuals that can interbreed and produce fertile offspring (based on the Biological Species Concept). Over time, species can diverge due to evolutionary processes

Symbiosis | Close and long-term biological interaction between two species

Sympatric Speciation | Speciation that occurs without geographic isolation, often due to genetic or behavioral factors that lead to reproductive isolation.

Taxonomy | The science of classifying organisms based on shared characteristics

Temporal Isolation | A type of prezygotic barrier where species reproduce at different times, preventing interbreeding.

Variation | The differences in traits among individuals within a population. These variations can be inherited and play a crucial role in natural selection

Vicariance | The physical splitting of a habitat, leading to geographical isolation and allopatric speciation.