Glossary
Adaptive evolution : genetic changes in a population that confer directional changes in a fitness-related trait. The direction of trait evolution is determined by the new phenotypic optimum, whilst the magnitude of change results from the strength of selection (genetic variation and heritability).
Baldwin effect : a novel state of a trait that emerges/changes via plastic mechanisms that is subsequently reinforced by genetic mechanisms that stabilize the trait across generations.
Bogert effect : the effect of plasticity in masking genetic variation from selection. Common examples include thermoregulatory behaviours in ectotherms.
Breeder’s equation : can be used to quantify the expected difference in mean trait value as the product of the heritability of the trait (\(h^{2}\)) and the selection differential the trait is exposed to (\(S\)): \(Z=\ h^{2}S\).
Critical rate of change : The maximum rate of environmental change the population can handle. Exceeding this limit inevitably results in a population decline towards extinction.
Environmental changes : a shift in abiotic (e.g., temperature and precipitation) and/or biotic factors (e.g., predation risk and community structure) that shifts the phenotypic optimum of a trait.
Environmental novelty : the degree to which biotic and abiotic factors differ between present and past. This can be quantified by the distance the phenotypic optimum has moved relative to the optimum in a normal environment.
Lag load : the gap between the moving phenotypic optimum and the mean trait value in the population.
Life history strategies : the suite of vital rate functions (e.g., survival, growth, reproduction) and associated phenotypes (e.g., morphology, behaviour, offspring investment) that work together to optimize the fitness of individuals and viability of populations over time.
Moving optimum theory : a body of work showing that, at any point in time, there is a phenotypic optimum that maximizes the fitness of individuals. This optimum can change over time due to biotic and abiotic factors. In turn, populations track the moving optimum, at a certain lag, via plasticity and/or adaptive evolution.
Phenotypic lag : a gap between the moving phenotypic optimum and the population mean trait.
Phenotypic optimum : the phenotype that maximizes fitness at a point in time.
Phenotypic plasticity : environmentally induced changes in an individual’s phenotype without changes in its genetic makeup.
Plasticity-first hypothesis : genetically based variation in plasticity among individuals in a population responds to selection in a novel environment. This initial variation in plasticity allows for the population to persist when it would not have been able to do so if it were plastic and then to respond to selection.
Rate of mean change : the direction and magnitude of differences in average environmental values (e.g., temperature and precipitation) over time.
Temporal autocorrelation : the correlation of terms in series separated by a time interval. Degree of autocorrelation is often described by the “colour of noise” where negative autocorrelation yields blue noise, zero autocorrelation yields white noise and positive autocorrelation yiels red noise.
Temporal refugia : a period of time where the degree/number/duration of perturbations in the environment that negatively affect fitness are reduced, allowing for intermittent rescues in population size and structure.
Trait heritability : the proportion of trait variance that is a consequence of additive genetic variance.
Transient dynamics : short-term fluctuations in population size/structure that arise due to both (1) perturbations in the strucuture and/or size of the population and (2) probabilistic events (e.g., survival and reproduction) as the population approaches an equilibrium.
Variability : the variance of an environmental variable (e.g., temperature and precipitation) value over time.
Vital rates : a component of fitness (e.g., survival, growth, reproduction, stasis) that varies across the structured life-cycle of an organism (i.e., age, stage, size).