adaptation:
1: the process of adjustment of an individual organism to environmental
stress; adaptability;
2: process of evolutionary modification which results in improved survival
and reproductive efficiency;
3: any morphological, physiological, developmental or behavioral character
that enhances survival and reproductive success of an organism
age structure: the number or percentage of
individuals in each age class of a population; age distribution; age composition
agroecosystem: an agricultural ecosystem: row crop (i.e. corn), solid
planted crop (i.e. wheat), perennial forage, managed forest, rangeland,
etc.; crop rotation
agroecotype: an edaphic ecotype adapted to cultivated soils
allele: any of the different forms of a gene occupying the same locus
(q.v. on homologous chromosomes), and which undergo meiotic pairing (q.v.
and can mutate one to another)
amensalism: an interspecific interaction in which one organism, population or species is inhibited, typically by toxin produced by another (amensal), which is unaffected
androdioecious: used of plant species having male and hermaphrodite flowers on separate plants
archetype: 1. a perfect or typical specimen; 2. an original model or pattern; prototype
bottleneck: a sudden decrease in the size of a population with corresponding reduction of total genetic variability
bottleneck effect: a conceptual occurence of genetic drift in populations reduced in size through fluctuations in abundance.
colonization:
1: the successful invasion of a new habitat by a species
2. the occupation of bare soil by seedlings or sporelings
commensalism: symbiosis in which one species derives benefit from a common food supply whilst the other species is not adversely affected
competition:
1: the simultaneous demand by two or more organisms or species for an
essential common resource that is actually or potentially in limited supply
(exploitation competition)
2: the detrimental interaction between two or more organisms or species
seeking a common resource that is not limiting (interference competition)
3: the tendency of neighboring plants to utilize the same quantum of
light, ion of a mineral nutrient, molecule of water, or volume of space
(mechanistic; Grime, 1979)
4: an interaction between species in a mixture in which each lowers the
net reproductive rate of the other (demographic outcome)
competitive exclusion: the exclusion of one species by another when they compete for a common resource that is in limited supply
competitive exclusion principle: the principle that two species having identical ecological requirments cannot coexist indefinitely; complete competitors cannot coexist
demography: the study of populations, especially of growth rates and age structure
dioecious: used of plants or plant species having male and female reproductive organs on different individuals; dioecy
ecological guild:
1: a group of
species having similar ecological resource requirements and foraging strategies,
and therefore similar roles (niches) in the community
2:
groups of species that exploit resources in a particular way (Silvertown,
2001)
ecology: the study of the interrelationships between living organisms
and their environment
ecosystem: a community of organisms and their physical environment interacting
as an ecological unit; the entire biological and physical content of a biotope
ecotype:
1: a locally adapted population; a race or infraspecific group having distinctive
characters which result from the selective pressures of the local environment;
ecological race;
2: a subunit capable of interbreeding with members of that and other ecotypes
q.v. comprising individuals capable of interbreeding with members of that
and other ecotypes within the ecospecies but remaining distict through selection
and isolation;
3: biotype
evolution
1: Any gradual directional change, unfolding;
2: Any cumulative change in the characteristics of organisms or populations
from generation to generation; descent or development with modification;
3: change in the frequency of genes in a population
fecundity
1: the potential reproductive capacity of an organism or population,
measured by the number of gametes or asexual propagules (Lincoln et al., 1998)
2: potential fertility or the capability of repeated fertilization.
Specifically the term refers to the quantity of gametes, generally eggs,
produced per individual over a defined period of time.
fitness:
1: the relative competitive ability of a given genotype conferred
by adaptive morphological, physiological or behavioral characters, expressed
and usually quantified as the average number of surviving progeny of one
genotype compared with the average number of surviving progeny of competing
genotypes; a measure of the contribution of a given genotype to the subsequent
generation relative to that of other genotypes (Lincoln, et al., 1998)
2: the relative ability of an organism to survive and transmit its genes
to the next generation
founder effect: that only a small fraction of the genetic variation of a parent population or species is present in the small number of founder members of a new colony or population
frequency-dependent selection: selection occurring in the situation in which the relative fitness of alternative genotypes is related to their frequency of occurrence within a population
genetic drift: the occurence of random changes in
the gene frequencies of small isolated populations, not due to selection,
mutation or immigration; drift; Sewall Wright effect.
genotype:
1: The hereditary or genetic constitution of an individual; all the genetic
material of a cell, usually referring only to the nuclear material;
2: All individuals sharing the same genetic constitution; biotype;
3: The specimen on which a genus-group taxon is based; the primary type
of the type species
guild:
1: a group of species having similar ecological resource requirements and
foraging strategies, and therefore similar roles (niches) in the community
2: groups of species that exploit resources in a particular way (Silvertown,
2001)
gynodioecious: used of plants or plant species
having female (pistillate) and hermaphrodite (perfect) flowers on separate
plants in a population or species
habitat: the locality, site and particular type of local environment
occupied by an organism (for us, a weed)
Hardy-Weinberg equilibrium: the maintenance of more or less constant allele frequencies in a population through successive generations; genetic equilibrium
Hardy-Weinberg law: that allele frequencies will
tend to remain constant from generation to generation and that genotypes will
reach an equilibrium frequency in one generation of random mating and will
remain at that frequency thereafter; demonstrating that meiosis and
recombination do not alter gene frequencies
hybridization: any crossing of individuals of different genetic
compostion,
typically belonging to separate species, resulting in hybrid offspring
introgression: the spread of genes of one species into the gene pool
of another by hybridization and backcrossing; introgressive hybridization
life history:
1: the significant features of the life cycle
through which an organism passes, with particular reference to strategies
influencing survival and reproduction
2: how long it typically lives, how long it usually takes to reach reproductive
size, how often it reproduces and a number of other attributes that have
demographic and fitness consequences (Silvertown & Charlesworth, 2001)
microhabitat: a very localized habitat (Example: on the size scale
of an individual seed in the soil seed bank)
microsite: analogous to a microhabitat; ex. the site perceived by
a seed in the seed bank, or a seedling in a field.
mortality: death rate as a proportion of the
population expressed as a percentage or as a fraction; mortality rate; often
used in a general sense as equivalent to death
•density-dependent mortality:
mortality and a decrease in population density (numbers per unit area) due to
the effects of population density (self-thinning)
•density-independent mortality:
mortality and a decrease in population density due to any factor which is
independent of population density
mutualism: a symbiosis in which both organisms benefit, frequently a relationship of complete dependence
natural selection:
1: the non-random and differential reproduction of different genotypes acting
to preserve favorable variants and to eliminate less favorable variants;
2: viewed as the creative force that directs the course of evolution by
preserving those variants or traits best adapted in the face of natural
competition
3: essence of theory of evolution by natural selection is that genotypes
with higher fitness leave a proportionately greater number of offspring,
and consequently their genes will be present in a higher frequency in the
next generation
niche: the ecological role of a species in a community; conceptualized
as the multidimensional space, of which the coordinates are the various
parameters representing the condition of existence of the species (n-dimensional
hypervolume), to which
it is restricted by the presence of competitor species; sometimes used loosely
as an equivalent of microhabitat in the sense of the physical space occupied
by a species
parasitism: an obligatory symbiosis between
individuals of two different species, in which the parasite is metabolically
dependent on the host, and in which the host is typically adversely affected by
rarely killed
phenotype: The sum total of observable structural and functional properties
of an organism; the product of the interaction between the genotype and
the environment; reaction type; phenome
phenotypic plasticity:
1: The capacity of an organism to vary morphologically,
physiologically or behaviorally as a result of environmental flucuations;
reaction type
2: the capacity for marked variation in the phenotype as a result of
environmental influences on the genotype during development [during the plants
life history]
population:
1: all individuals of one or more species within a prescribed area;
2: a group of organisms of one species, occupying a defined area and usually
isolated to some degree from other similar groups
population biology: Study of the spatial and temporal distributions
of organisms
population genetics: Study of gene frequencies and selection pressures
in populations
population genetic structure: the genetic composition and gene frequencies of individuals in a population
population dynamics: the study of changes within populations and of the factors that cause or influence those changes; the study of populations as functioning systems.
productivity
1: the potential rate of incorporation or generation of energy or organic
matter by an individual, population or trophic unit per unit time per unit area
or volume; rate of carbon fixation
2: fertility
somatic polymorphism: production of different plant
parts, or different plant behaviors, within the same individual plant; the
expression of somatic polymorphism traits is not much altered by the
environmental conditions it encounters (as opposed to phenotypic
plasticity)
speciation:
1: The formation of new species;
2: the splitting of a phylogenetic lineage;
3: acquistion of reproductive isolating mechanisms producting discontinuities
between populations;
4: process by which a species splits into 2 or more species
species:
1: A group of organisms, minerals or other entities formally recognized
as distinct from other groups;
2: a taxon of the rank of species; in the hieracrchy of biological classification
the category below genus; the basic unit of biological classification; the
lowest principal category of zoological classification
3: A group of morhologically similar organisms of common ancestry that under
natural conditions are potentially capable of interbreeding
4: A species is a group of interbreeding natural populations that are reproductively
isolated from other such groups
species-group: A group of closely related species, usually with partially
overlapping ranges; sometimes used as an equivalent of superspecies.
[NOTE: the idea here is that the related species occupy overlapping
niches]
trait:
1: a character: any detectable phenotypic property of an organism
2: any character or property of an organism
3: a characteristic feature or quality distinguishing a particular person
or thing
