theory
explanatory statements or arguments related to particular sets phenomena supported by observation and experiment
data
observations, measurements, facts (known or assumed) that form the basis for a conclusion; singular datum
reproductive fitness
a measure of the success of an individual in the production of offspring across generations; your children, and their children, and so on all constitute your reproductive fitness
epigenetic
mechanisms acting during mitosis (development) to modify gene expression without modifying the actual DNA sequence; may result in heritable variation
adaptive radiation
the opportunistic and relatively rapid diversification of new forms into new ecological zones through a series of speciation events
immutable
unchanging over time, or unchangeable; an idea traceable to the greek philosopher aristotle, stating that forms exist today as they were when created, have not changed in the past, and cannot change in the future
phenotypic plasticity
a potential for individuals to modify their phenotype in response to variation in external conditions in order to maintain homeostasis and function
sample
a subset of a whole that represents its qualities with regard to the characteristics under study; for example, if three-quarters of a population of university students have a piercing, approximately the same proportion in a sample selected from that population should have a piercing
great chain of being
Aristotle’s ordered, hierarchal, and static view of the world
taxonomy
the method by which organisms are classified and assigned to a group (a taxon; plural taxa) based on shared biological, ecological, and behavioural relationships
extinction
the complete dissa[earance of particular species owing to factors that may be internal (related to the organisms biology) or external (related to environmental change over which the organism has no influence)
phylogenetic
relating to evolutionary histories of ancestry and descent
microevolution
small scale evolutionary events occurring within a population over the span of a few generations, affecting the frequency of specific characters and not involving species formation
biogeography
the study of the geographic distribution of organisms, habitats, and evolutionary history as it related to landscape and ecology
directional selection
a form of positive or negative selection resulting in a shift in phenotypes toward one end of the distribution, typically occurring in dynamic and changing environments
morphospecies
designation of species in the fossil record according to similarity in form irrespective of time
parapatric
refers to species whose ranges are contiguous but not overlapping; gene flow is possible
sympatric
refers to species that coexist in the same geographic region
variability
the tendency for members off a population to exhibit different versions of a particular trait
allopatric
refers to species that “live apart” and do not occupy the same geographic locale; allopatric species are presumed to exist in genetic isolation
punctuated equilibrium
a pattern of evolution characterized by periods of stasis interrupted by rapid evolutionary change; more commonly found in small, peripheral populations on the edge of a species range
constraint
genetic of functional limitation on the activity or expression of a characteristic
variation
the expression of differences for a characteristic among members of a population
anagenesis
a pattern of slow, linear evolutionary change, also known as Darwinian gradualism
stabilizing selection
a form of selection favouring the most common phenotype at the expense of extreme expressions of a character
homologous
referring to homology, which is similarity among characters as a result of inheritance from a common ancestor
founder effect
the potentially biased sampling of the genetic variation in a species due to the isolation of a small number of its members
homoplasy
analogous characters in different taxa that appear as a result of independent evolution; such a character is not present in the last common ancestor of the taxa in question
gene flow
the movement of genes with or without the movement of individuals over geographic space
lactase persistence
in humans, the continues production past childhood of the enzyme lactase necessary for digesting the milk sugar lactose
adaptationist
a perspective that commonly seeks an adaptive explanation or mechanism for the presence or form of a particular phenotypic character
balanced polymorphism
polymorphism means “many types” and in genetic terms denotes phenotypes established at proportions that do not require mutation to maintain their existence. Balanced polymorphism occurs when a heterozygote has a selective advantage over altnernative homozygotes, thereby maintaining allele diversity within the population
convergence
a path toward development of homoplasy; evolution acts on different ancestral structure to converge upon a similar outcome in response to similar adaptive pressures
parallelism
a path toward development of homoplasy; evolution modifies an ancestral character to achieve similar outcomes in response to similar adaptive pressures
genetic bottleneck
a sudden constriction on the genetic diversity appearing in a generation, commonly associated with a reduction in population size