The variational properties of an organism, as distinct from its functional properties, are those properties relating principally to the production of variation among its offspring, but in a broader sense can include phenotypic plasticity. It is an umbrella concept introduced in
so that the classical concepts of pleiotropy

Pleiotropy

Pleiotropy occurs when one gene influences multiple phenotypic traits. Consequently, a mutation in a pleiotropic gene may have an effect on some or all traits simultaneously...

, canalization

Canalization

Canalization may refer to:* Canalization, the process of introducing weirs and locks to a river so as to secure a defined depth suitable for navigation*Channelization, the process of modifying the course of a stream so that it follows a restricted path...

, developmental constraints, morphological integration, developmental homeostasis

Homeostasis

Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...

, etc., and later concepts such as robustness

Robustness

Robustness may refer to:*In biology**Robustness , the persistence of a system’s characteristic behavior under perturbations or conditions of uncertainty...

, neutral networks, modularity

Modularity

Modularity is a general systems concept, typically defined as a continuum describing the degree to which a system’s components may be separated and recombined. It refers to both the tightness of coupling between components, and the degree to which the “rules” of the system architecture enable the...

, the G-matrix, distribution of mutation effects, etc., could be thought of as different aspects of a single phenomenology. While the functional properties of an organism determine is level of adaptedness

Adaptation

An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....

 to its environment, it is the variational properties of a species that chiefly determine its evolvability

Evolvability

Evolvability is defined as the capacity of a system for adaptive evolution. Evolvability is the ability of a population of organisms to not merely generate genetic diversity, but to generate adaptive genetic diversity, and thereby evolve through natural selection.In order for a biological organism...

.

Variational properties include the production of DNA sequence variation, epigenetic variation, and phenotypic variation. While the genome is typically thought of as the storehouse of information that generates the organism, it can also be seen as the set of heritable degrees of freedom for varying the organism. DNA thus has both a generative role in the organism, and variational role in the lineage.

Prior to its introduction into evolutionary biology, the phrase "variational properties" already had usage in various areas of mathematics and physical sciences