Eco-evo Glossary

An ongoing glossary of important terms for the study of eco-evolutionary dynamics.

A

• Adaptive divergence: When different populations of the same species are subjected to different environments, local phenotypic adaptations can become heritable adaptations (Hendry, unpublished  book).
• Adaptive evolution: Evolution that increases the frequency of adaptive alleles in a population; Evolution that increases the fitness of a population.
• Adaptive landscape: A multi-dimensional landscape depicting mean fitness for certain mean phenotype(s) of a population. Each dimension is a trait. The adaptive landscape is a tool to predict how phenotype and fitness will change over time (Hendry, unpublished book).
• Adaptive peak: In a fitness landscape, an adaptive peak is the highest local adaptive trait.
• Adaptive plasticity: Phenotypic changes that are in the same direction favored by selection in a new environment (Ghalambor et al. 2007).
• Adaptive radiation: New, unfilled niches become available and species evolve and fill these niches.
• Adaptive ridge: Two fitness peaks without an adaptive valley between them. In other words, there are two phenotypes that are ideal in a given environment, and there is no fitness loss to switch between them. 
• Additive genetic variance: Variance due to genes that all contribute to a single trait. If multiple genes all contribute a little to the same phenotype (as in a polygene), their effects add together to create the final phenotype and their contributions and corresponding variance are considered additive.
• Admixture mapping: A genetic technique to determine the many genes that contribute to a trait in hybrid zones (where two populations interbreed). Admixture mapping is association mapping in hybrid zones (Hendry, unpublished book).
• Allee effect: When population density is positively correlated with individual fitness (Wikipedia).
• Allelopathy: When an organism can release chemicals that affect other organisms. In positive allelopathy, these chemicals have a positive effect on others; in negative allelopathy, these chemicals have a negative effect on others (Wikipedia).
• Allochronic: Describes samples taken from the same population at different times. This is a method to measure evolution (Hendry, unpublished book).
• Allopatry: Describes populations not in geographic contact.
• Allopatric speciation: Speciation that takes place among two populations not in geographic contact and gene flow cannot occur. See also: Parapatric speciation.
• Anagenesis: Evolution of a population without speciation taking place. I.e., a population's allele frequencies change over time as a whole (Clauset 2013).
• Association mapping: A genetic technique to determine the many genes that contribute to a trait. It is very similar to linkage mapping, but the difference is association mapping uses traits from whole populations. Association mapping in hybrid zones is called admixture mapping (Hendry, unpublished book). 
• Assortative mating: choosing mates based on phenotypes. Antonym: panmixia.

B

• Backcross: A technique used in genetics where an offspring (e.g. F1 or F2) is bred with a parent (P). This is useful to determine the genotype of the offspring. 
• Baldwin Effect: Environmentally-induced variation leads to (genetic) adaptive evolution. 
• Bivariate Quadratic selection gradient: Partial regression coefficient of the cross-product of pairs of each trait deviation (Hendry, unpublished book).
• Breeding value: The trait value of a parent measured as the mean expected value of their offspring (Hendry, unpublished book).
• Broad-sense heritability (H^2): a measure of all the sources of genetic heritability on a phenotype, including epistasis, dominance and recessiveness, additivity, and maternal and paternal effects. Measured as the ratio of the variance of genotype and the variance of phenotype: Var(G)/Var(P). Contrast with narrow-sense heritability (h^2).

C

• Canalisation: Biological robustness; the ability of a population to produce the same pheontype regardless of environment or genotype (Wikipedia). 
• Candidate genes: A genetic technique to determine the role of genes in trait expression. Candidate genes are of known function in model organisms and are targeted for study in non-model organisms to see if that gene functions similarly in the non-model organism (Hendry, unpublished book).
• Character convergence: When a species faced with competition for a shared resource becomes more efficient at using that resource (Ingram et al. 2012). To me personally, this term is misleading because the word convergence implies that two things are becoming one, but that doesn't occur in character convergence. What occurs is increased efficiency. 
• Character displacement: When a species faced with competition for a shared resource switches to primarily using an alternative resource to avoid competition (Ingram et al. 2012). See "Ecological character displacement" and "Reproductive character displacement."
• Coevolutionary dynamics: Adaptation by one species causes counter-adaptation by another, ad infinitum (Garant et al. 2007).
• Coevolutionary theory:
• Common garden experiment: When organisms from a variety of environments are transported into a similar environment. Often used to test if there is a genetic component to phenotype. Also called a transplant experiment (Wikipedia).
• Community phylogenetics:
• Compensatory: Describes a population trait (e.g. mortality) where the rate decreases when the size of the population decreases (fishbase.org). Antonym: depensatory.
• Competitive exclusion principle: Two species cannot coexist if they use all the same resources in the same way, but they can coexist if they use resources differently (Pfenning and Pfenning 2009).
• Contemporary evolution: evolution on ecological time scales; rapid evolution (Garant et al. 2007).

D

• Darwin (unit): A unit of evolution--change in the mean value of a trait over time; ln(mean trait value)t2 - ln(mean trait value)t1,where t=time (Hendry, umnublished book). 
• Deme: A population of individuals of one species that breed with each other and share a distinct gene pool (Wikipedia).
• Depensatory: Describes a population trait (e.g. mortality) where the rate increases when the size of the population decreases (fishbase.org). Antonym: compensatory.
• Directional selection: Selection that favors one trait over another, eventually leading to the extermination of the less adaptive trait. Synonym: linear selection.
• Dispersal: movement of individuals (Garant et al. 2007).
• Diverging selection: selection leads to the appearance of a new trait morph.

E

• Eco-evolutionary dynamics: "Genetic and phenotypic interactions within and among populations and species" strongly influencing "the interplay of ecological and evolutionary changes."
• Ecological character displacement: When traits in two populations diverge due to selection for differential resource use (Pfenning and Pfenning 2009).
• Ecological genetics:
• Ecological inheritance: 
• Ecological speciation: 
• Ecological stoichiometry: 
• Ecosystem engineer: 
• Ecophenotype: 
• Evolutionary metacommunities: 
• Evolutionary quantitative genetics:
• Evolutionary rescue: When environmental changes cause population decline, but evolution of the population increases population size before it goes extinct. 
• Evolvability: A measure of evolutionary potential, calculated as the additive genetic variance divided by the square of the mean trait value (Hendry, unpublished book).

F

• F1: Filial generation 1. These are the offspring of two individuals from the P (parental) generation.
• F2: Filial generation 2. These are the offspring of two individuals from the F1 generation.
• F3: Filial generation 3. These are the offspring of two individuals from the F2 generation.
• Fst: A measure of differentiation in neutral genes between populations (Sanford and Kelly 2011).
• Function-valued traits: Phenotypes that are continuous variables. Example: growth curve (Hendry, unpublished book).

G

• Gasterosteus aculeatus: The Linnean classification for threespine stickleback.
• Gene flow: Movement of genes (Garant et al. 2007).
• Gene knockout studies: 
• Genetic accommodation: Tentative definition (I don't yet fully understand this term): When environmentally- or genetically-induced phenotypic variation leads to changes in how associated genes are regulated (Crispo 2007).
• Genetic assimilation: A type of genetic accommodation. When environmentally-induced phenotypic variation leads to adaptive heritable variation (Ghalambor et al. 2007).
• Genetic compensation: When environmentally-induced phenotypic variation is maladaptive and populations change genetically to compensate (Crispo 2007).
• Genome scans: a genetic technique where a large number of genetic markers (such as single-nucleotide polymorphisms [SNPs]) are determined in many individuals from many populations or species. The idea is to search for markers that show the smallest or largest differences among groups (Hendry, unpublished book).
• Genotype by environment interaction (G x E): how genotypes respond differently across different environments. Can only refer to populations and groups of genotypes.
• Guild: a collection of species that use resources in similar ways (Morin 2011).

H

• Haldane: A unit of evolution--change in the standard deviation of a trait per generation; [ln(mean trait value)_t2 - ln(mean trait value)_t1]/s/generations. Haldanes only measure sustained directional change.
• Heritability: A measure of how traits are passed on from parents to offspring. See broad-sense and narrow-sense heritability.
• Heterosis: The case of an offspring having superior qualities than both its parents.

I

• Intraguild predation: When a predator is also a competitor; it also competes for resources within a trophic level (Ingram et al. 2012).
• Introgression: when genes from one population are introduced to another through hybrids (Rheindt and Edwards 2011). 

J

K

L

• Lande equation: ∆z = Gβ. Relates evolutionary change (∆z) as a function of additive genetic variation (G) and selection strength (as selection differential, β) (Hendry, unpublished book).
• Life history theory:
• Linear selection: Selection that favors one trait over another, eventually leading to the extermination of the less adaptive trait. Synonym: directional selection.
• Line-cross analysis: Genetic analyses based on comparison of pure crosses, F1 hybrids, F2 hybrids, and backcrosses to parental forms (Hendry, unpublished book).
• Linkage disequilibrium: Non-random gene flow.
• Linkage mapping: A genetic technique to determine sections of a genome that are physically close together. 
• Locus

M

• Magic traits: traits under selection from the environment and mating, or "phenotypic traits involved in both local adaptation and mating decisions." (Haller 2011)
• Muggle traits: traits that would be magic but aren't in certain environments.

N

• Narrow sense heritability (h^2): A measure of how much heritability is due just to additive genetic effects on phenotype. It is measured as the ratio of additive genetic variance and total phenotypic variance: Var(A)/Var(P). Narrow sense heritability is proportional to the rate of short-term responses to selection (Bolnick et al. 2011). Contrast with broad-sense heritability (H^2). 
• Niche complementarity: the tendency for phenotypically divergent species to compete less intensely (Bolnick et al. 2011).
• Niche construction:

O

• Organic selection: The ability of plasticity to increase survival (Crispo, 2007). 
• Orthoplasy: When environmental variables cause phenotypic changes that direct genetic changes (Crispo, 2007).

P

• Panmixia: Random mating. Antonym: assortative mating.
• Panmitic: Describes a population with random mating. This is the adjective form of panmixia, above.
• Parapatric speciation: Speciation that takes place between to populations whose ranges are adjacent.
• Parapatry: Describes two populations whose ranges are adjacent.
• Phenotypic plasticity: When an organism can change its phenotype (genotype remains constant).
• Physiological time: A measure incorporating time and temperature that is applied to poikilotherms. It considers that development and growth are very reliant on external temperature as well as time in order to come to completion (Glossary Ecology, biophyics.sbg.ac.at/home.htm).
• Phytophagous: Feeding on plants.
• Pleiotropy: One locus affecting multiple phenotypes.
• Polymorphism: When multiple morphs of a trait exist.
• Polyphenism: When one gene can produce multiple phenotypes.
• Portfolio effect: When subunits have opposite values such that the overall average value is intermediate. It is often used to describe population density. For example, if groups of salmon return to a river at different times of the year spanning the whole year, the average population of salmon in the river is constant over the whole year even though the subgroups are variant (Bolnick et al. 2011).
• Purifying selection: Selection that continues to favor the most common phenotype and reduces phenotypic variance. Also called stabilizing selection. 

Q

• Qst: A measure of the differentiation of continuous (AKA quantitative) phenotypic traits between populations (Sanford and Kelly 2011).
• Quadratic selection differential: Considers non-directional selection. When this term is negative, selection is stabilizing; when this term is positive, selection is disruptive. Also known as a partial regression coefficient of the squared deviance of a trait (Hendry, unpublished book).
• Quantitative genetics: Statistically dividing genetic variation into its parts: epistasis variance, additive genetic variance, dominance variance, maternal effects variance, and environmental variance (Hendry, 2013).
• Quantitative trait: A trait controlled by multiple loci (Savolainen et al. 2013).
• Quantitative trait locus (QTL): Stretches of DNA that contain some of the many genes that control a quantitative trait (Wikipedia; Savolainen et al. 2013).

R

• Rapid evolution: Evolution on ecological time scales; contemporary evolution (Garant et al. 2007). Evolution is considered rapid if its effect on ecology is greater than or equal to the effect of traditional ecological drivers such as predation or temperature.
• Reaction norm: pattern of plasticity; “The particular way an individual's (or genotype's) phenotype varies across environments” (Ghalambor et al. 2007).
• Reinforcement: "The evolution of traits that minimize hybridization between species" (Pfenning and Pfenning 2009). For example, it is maladaptive for individuals in two different populations to mate if they produce sterile offspring. Therefore, individuals that mate only within their population will tend to produce more offspring and the two populations will slowly cease to interbreed. In this way, reinforcement can complete speciation. 
• Reproductive character displacement: Two populations evolve traits due to selection against interpopulation reproduction (Pfenning and Pfenning 2009).

S

• Selection coefficient (s): a measure of the relative fitness of a trait. It compares the fitness of one trait to another (Wikipedia).
• Selection differential (S): Describes total selection acting on a trait; the difference between the mean trait value of a selected group and the mean of the entire population before selection. Typically described as linear or quadratic. Specifically, it is calculated by subtracting the mean trait value before selection from the mean trait value after selection (Hendry, unpublished book).
• Short tandem repeats (STR):
• Single nucleotide polymorphism (SNP).
• Species diversity: A measure of species that takes into account richness (# of species) and their relative abundances. 
• Species evenness: 
• Species richness: The number of species in a given area. 
• Stochastic: Describing a random process or something with a random probability.
• Squib traits: trivial magic traits.
• Stenotopic: Able to tolerate or adapt to only a small range of environmental conditions (Wikipedia). 
• Sympatric speciation: Speciation that occurs within a population such that the resulting species' ranges overlap.
• Sympatry: Describes distinct populations with overlapping ranges.
• Synchronic: Describes samples taken from two different populations from the same time. Example: Samples taken from two different populations with a common ancestor from the same time period. (Hendry, unpublished book).

T

• Transgenerational plasticity (TGP): when environmental cues by a parent before fertilization affect offspring reaction norms (phenotypes). No DNA is altered, so it's not true evolution. A more generalized version of 'maternal effects.'
• Transgenics: 
• Trophic level: a collection of species that obtains energy in a similar way (Morin 2011). For example, organisms that obtain energy from the sun (e.g. plants and diatoms) are the lowest trophic level, and all organisms that obtain energy by eating those plants are the next highest trophic level. 

U

• Univariate linear selection gradient: A strategy to better separate direct and indirect selection; partial regression coefficient of each trait.
• Univariate quadratic selection gradient: A strategy to better separate direct and indirect selection; partial regression coefficient of each trait deviation squared.

W

X
Y
Z

• Zero-sum ecological drift: Within an ecosystem, individuals are randomly replaced regardless of taxonomic identity (Ricklefs and Renner 2012).

References (not complete)

• Bolnick, D. I., P. Amarasekare, M. S. Araújo, R. Bürger, J. M. Levine, M. Novak, V. H. W. Rudolf, S. J. Schreiber, M. C. Urban, and D. a Vasseur. 2011. Why intraspecific trait variation matters in community ecology. Trends in ecology & evolution 26:183–92.
• Garant, D., S. E. Forde, and A. P. Hendry. 2007. The multifarious effects of dispersal and gene flow on contemporary adaptation. Functional Ecology 21:434–443.
• Ghalambor, C. K., J. K. McKay, S. P. Carroll, and D. N. Reznick. 2007. Adaptive versus non-adaptive phenotypic plasticity and the potential for contemporary adaptation in new environments. Functional Ecology 21:394–407.
• Ingram, T., N. J. B. Kraft, P. Kratina, L. Southcott, R. Svanb, and D. Schluter. 2012. INTRAGUILD PREDATION DRIVES EVOLUTIONARY NICHE SHIFT IN THREESPINE STICKLEBACK. Evolution 66:1819–1832.
• P. Morin, Community Ecology, 2nd ed (2011).
• Pfenning, K. S., and D. W. Pfenning. 2009. Character Displacement: Ecological and Reproductive Responses to a Common Evolutionary Problem. Chicago Journals 84:253–276.
• Sanford, E., and M. W. Kelly. 2011. Local adaptation in marine invertebrates. Annual review of marine science 3:509–35.
• Savolainen, O., M. Lascoux, and J. Merilä. 2013. Ecological genomics of local adaptation. Nature reviews. Genetics 14:807–20.