Hierarchy Theory of Evolution Glossary

Attributes that ensure greater stability and persistence of an individual entity, typically envisioned as maximizations of the match between biological entities and their immediate environment, resulting in gains in fitness.


Aggregate traits
Cumulative properties or combined attributes of entities at the lower level.


Average path length
The mean number of nodes along the shortest path connecting two nodes in a network.


A highly integrated, discrete assemblage of non-conspecific avatars occupying a particular biotope.


Boundary conditions
Interactions of entities at a higher level that exert constraints upon entities at the adjacent focal level in a hierarchy.


The enduring and robust organismal phenotypic stability.


In philosophy of biology, a collections of entities whose membership is based exclusively on shared properties.


Coordinated stasis
The empirical pattern in the fossil record characterized by geographically co-localized avatars persisting in stasis over extended intervals of geologic time.


Secondary extinction
Extinction triggered by the removal of other species.


Degree distribution
In network theory, the frequency distribution of the number of links per node (vertex connectivity).


Disparity pattern
Evolutionary pattern describing the dynamics of change in the attributes (typically phenotypic) of evolving individuals at a given level of a genealogical hierarchy.


Diversity pattern
Evolutionary pattern describing the dynamics of change in the quantity of evolving individuals at a given level of a genealogical hierarchy.


Downward causation
The effect that the upper level exerts on the lower level in a hierarchy.


A non-deterministic sorting process owing to chance.


Effect selection (effect hypothesis)
Differential reproductive success among species within clades resulting from selection operating on aggregate traits that ultimately reside at the organismal level.


Emergent traits
Properties that cannot be reduced to or be expressed in terms of properties of entities at the lower level.


The fate of information that can be altered as it is transmitted from ancestors to descendants in biological and sociocultural systems.


Evolutionary capacitance
The buffering capacity of genetic networks to suppress phenotypic variance in a population in face of environmental perturbations.


Evolutionary driver
An extrinsic factor causing evolutionary change, typically an abiotic environmental factor affecting climatic, lithological, and geochemical processes.


Evolutionary pattern
An empirically discernible regularity in the history of a biological system.


Measure of degree of replication success.


Focal level
Level in a hierarchy at which a phenomenon in question is observed.


Genetic drift
Random fluctuations in allele frequencies due to sampling effects in finite populations.


Hereditary replicator
An entity generating progeny that might differ from the ancestral form.


An arrangement of entities in which some are represented as being above, below, or at the same level as other entities.


Higher level
A more inclusive level in a hierarchy relative to the focal level.


A class of entities at the same hierarchical level.


A node in a network with a disproportionately large number of connections.


In philosophy of biology, an integrated, spatiotemporally constrained (i.e. historical) system.


Initiating conditions
Interactions of entities at a lower level that affect the dynamics at the adjacent focal level in a hierarchy.


Active exchange of matter and energy in biological or sociocultural complex systems.


Entity that that interact with their environments in such a way as to make replication differential.


Kin selection
Population-level selection process that enhances the reproductive success of an organism’s relatives, even at a cost to the organism’s own survival and reproduction.


Degree of inclusiveness, relative rank, or significance in a hierarchy.


Lower level
A less inclusive level in a hierarchy relative to the focal level.


Mass extinction
A potential consequence of sorting at supraspecific levels, where entire clades may become extinct as a result of environmental changes or contingent factors.


Natural selection
Selection operating on phenotypic properties of individual organisms.


Nested compositional hierarchy
1. A pattern of relationship among entities based on the principle of increasing inclusiveness, so that entities at one level are composed of parts at lower levels and are themselves nested within more extensive entities.

2. An acyclical graph (mathematics).


A system of interacting entities that is conventionally represented by a graph, a collection of nodes (vertices) connected by links (edges).


Non-holonomic constraints
See Boundary conditions.


Non-proliferative replication
Replication mode resulting in the production of a single descendant from the parent.


Phylogenetic drift
A stochastic origination and persistence of species in the absence of environmental interaction.


Proliferative replication
Replication mode resulting in the production of multiple descendants from the parent (or parental pair).


Punctuated equilibria
The empirical pattern characterized by a prolonged period of phenotypic stasis and a relatively brief burst of phenotypic change triggered by speciation as documented in the fossil record.


Random walk
A pattern characterized by a succession of independent steps, where increases and decreases of a trait are equally probable.


Transmission of heritable information in biological or sociocultural complex systems.


Entity that pass on their structure (i.e., information) intact through successive generations.


An exceptionally high degree of tolerance against random failures and external perturbations.


Scale-free network
A network with few hubs and the majority of nodes with relatively few connections, so that
its degree distribution of vertex connectivity follows a power law function.


A deterministic process that represents a special type of sorting resulting from nonrandom differences in fitness, or replication success.


Simple replicator
Entity producing descendants identical to itself (clones).


Sloshing bucket hypothesis
A model of global evolutionary dynamics postulating a correlation between the level of perturbation in the economic hierarchy and the level in the genealogical hierarchy at which the evolutionary consequence is recorded.


Small world network
A network characterized by short mean path length.


A consequence of differential birth and death rates among genealogical individuals differing in their properties.


Segments of time-extended, population-level lineages demarcated by origin through speciation and demise through extinction.


Species drift
See Phylogenetic drift.


Species selection
Differential reproductive success among species within monophyletic groups favoring species that persist for long periods and speciate at higher rates.


Species selection sensu stricto
Species selection operating on emergent, heritable properties of species level.


A historical pattern characterized by little or no net change, typically showing minimal oscillations around a stable mean.


A network of functionally interdependent and structurally interconnected components comprising an integrated whole.


Taxic pattern
Historical pattern of species-level diversity.


A sustained directional change in a statistic descriptor for some attribute observed over time.


Transformational pattern
Historical pattern in morphological disparity at organismal level.


Turnover pulse
The empirical pattern of cross-lineage, synchronous, species-level transitions (speciation and extinction) as documented by the fossil record.


Upper level
See Higher level.


Upward causation
The effect that the lower level exerts on the upper level in a hierarchy.