definitions test 2 Flashcards
an introduced organism that negatively alters its new environment
invasive species
the presence of two or more species living in the same area
sympatry
a group of species that exploit the same class of environmental resources in a similar way
guild
a commonly mutualistic and intimate association between the roots of a plant and a fungus
mycorrhiza
scientific name of a phylum of small marine shellfish, sometimes called “lamp shells”
brachiopods
the largest ecological niche that an organism or species can occupy in the absence of interspecific competition and predation
fundamental niche
the tendency for coexisting species to
differ in their niche requirements
niche differentiation
the portion of its potential (fundamental) niche occupied by a species when competitors or predators are present
realized niche
occurring in different places; usually refers to geographical separation of species
allopatry
another word for plant-eating
phytophagous
the measurable physical difference between two species that has arisen by natural selection as a result of the selection pressures on one or both from competition with the other
character displacement
birds that feed on insects
insectivorous
Russian scientist who described the “competitive exclusion principle”
Georgy Gause
the range, for all important environmental features, within which individuals of a species can survive, grow, and reproduce
niche
the distribution of organisms in which individuals are closer together than they would be if they were randomly or evenly distributed
aggregated distribution
an individual liable to be, or actually, consumed (and hence killed) by a predator
prey
a population perceived to exist as a series of subpopulations, linked by migration between them
metapopulation
a consumer which attacks large numbers of large prey during its lifetime, but removes only a part of each prey individual, so that the effect, although often harmful, is rarely lethal in the short term, and never predictably lethal
grazer
the tendency for the death rate in a population to increase, or the birth or growth rate to decrease, as the population size increases
density dependence
an organism which is parasitized by a parasite
host
the average number of new infected hosts that would arise from a single infectious host in a population of susceptible hosts
basic reproductive number (R0)
an evolutionary theory that predicts the details of feeding behavior based on mathematical models
optimal foraging theory
insects in which the adults are free-living but eggs are laid in, on or near an insect host, after which the larva develops in the host (itself usually a pre-adult), initially doing little apparent harm, but eventually consuming and killing the host before or during the pupal stage
parasitoids
an organisms that consumes other organisms
predator
a microorganism or virus that causes disease
pathogen
an organism that obtains its nutrients from one or a very few host individuals, causing harm but not causing death immediately
parasite
interference amongst predators leading to a reduction in the consumption rate of individual predators which increases with predator density
mutual interference
the population size that needs to be exceeded for a parasite population to be able to sustain itself
threshold population size
a classic example of predator-prey oscillations is the relationship between the snowshoe hare and the ____
lynx
a consumer that invariably kills their prey, and consumes many prey items over the course of their life time
true predator
when selective predation favours the coexistence of prey species that might otherwise exclude one another
predator mediated coexistence
defense mechanisms that are always present in plants (eg. cell walls, waxy cuticle, bark, thorns)
constitutive defense
the defenses that are produced when a plant is injured or detects foreign pathogen (eg. toxic chemicals, pathogen degrading enzymes, deliberate cell suicide)
inducible defenses
a model frequently used to describe the dynamics of ecological systems in which two species interact, one a predator and one its prey
Lotka-Volterra Model
small sap-sucking insects that are “farmed” by ants
aphids
a close association between the individuals of pairs of species
symbiosis
any agent (living or otherwise) that acts as a carrier for a pathogenic organism and transmits it to a susceptible host
vector
a virus that attacks bacteria
phage
an interaction between the individuals of two (or more) species in which the growth, growth rate, and/or population size of both are increased in a reciprocal association
mutualism
random changes in gene frequency within a population resulting from sampling effects rather than natural selection, and hence of greatest importance in small populations
genetic drift
a group of bacteria that fix nitrogen in the root nodules of most leguminous plants
rhizobia
the small circular chromosome found inside mitochondria
mitochondrial DNA
a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor
clade
plant-defensive substances that can kill in small doses and tend to be induced by herbivore attacks
qualitative chemicals
mycorrhiza that penetrate within the roots of the host
arbuscular mycorrhiza
the process in which atmospheric nitrogen is converted into ammonia
nitrogen fixation
the existence within a species or population of different forms of individuals or “morphs”
polymorphism
the tendency of animals to return very close to their place of birth to breed
natal philopatry
plant-defensive substances that are digestion-reducing, rely on an accumulation of ill effects, and tend to be produced all the time
quantitative chemicals
The process by which members of two (or more) species contribute reciprocally to the forces of natural selection that they exert on each other
coevolution
differences in DNA that are favored in different individuals / the genetic diversity within a species that enables it to adapt to changing environmental conditions
adaptive variation
differences in DNA that do not affect fitness of the individuals
neutral variation
a technique to make many copies of a specific DNA region in vitro
polymerase chain reaction (PCR)
regions of DNA where the same small number of bases is repeated many times
microsatellites
determining the order of the four chemical building blocks - called “bases” - that make up the DNA molecule
sequencing
a genomic variant at a single base position in the DNA
single nucleotide polymorphism (SNPs)
the process in which the animal ingests part of its feces in order to increase nutrient uptake
refection (/pseudorumination/cecotrophy)
number of species present in a community
species richness
a flightless parrot form New Zealand
kakapo
a community where some species are competitively superior to others so that an initial colonizer of an opening left by a disturbance cannot necessarily maintain its presence there
dominance-controlled community
communities where a large number of species are approximately equivalent in their ability to colonize an opening left by a disturbance, are equally well fitted to the abiotic environment, and can hold the location until they die
founder-controlled community
photosynthesizing microscopic biotic organisms that inhabit the upper sunlit layer of almost all oceans and bodies of fresh water on Earth
phytoplankton
important pests of potatoes
colorado potato beetles
representation of feeding relationships in a community that includes all the links revealed by dietary analysis
food web
organisms that are typical of unstable or periodically extreme environments, e.g. deserts or ephemeral ponds, and characterized by a strong dispersal ability (typically smaller than equilibrium species and have shorter life cycles)
fugitive/pioneer/opportunist species
occurs when the severity of disturbance is insufficient to remove all the existing vegetation and soil from a site
secondary succession
collection of species that occur together in space and time
community
a community that returns rapidly to something like its former structure after a disturbance
resilient community
a community that undergoes relatively little change in its structure in the face of a disturbance
resistant community
the presumed endpoint of a successional sequence; a community that has reached a steady state
climax
a species whose removal would produce a significant effect in the community of which it is part, changing its fundamental nature
keystone species
spatially separate portions of a species’ population, between which there is only limited dispersal compared to the rate of dispersal within them
subpopulations
a tendency in a population for some factor to cause density to increase when it is low and to decrease when it is high
population regulation
the combined effects of all the factors and processes that affect population size (whether density-dependent or not)
determination of abundance
“killing power” of an environment
k-value
a series of sites that differ in age and succession levels since abandonment or disturbance
chronosequence
patches within which many species suffer local extinction simultaneously
gaps
which occurs when a predator reduces the abundance of its prey, and this cascades down to the trophic level
trophic cascade
succession in an area that has not previously been influenced by a community
primary succession
the nonseasonal, directional, and continuous pattern of colonization and extinction on a site by populations
succession
the amount of water that could be evaporated and transpired if there was sufficient water available (a measure of atmospheric energy)
potential evapotranspiration
enrichment of water body with plant nutrients
eutrophication
the diversity between two different regions, each with many communities
gamma diversity
this hypothesis explains how environmental temperature may affect a community of organisms
energy hypothesis
bottom-dwelling organisms in aquatic systems
benthic organisms
environments that are dominated by an extreme abiotic factor such as temperature or acidity
harsh environments
the study of distribution of species and community composition on islands
island biogeography
the increase in species richness if you move from the Arctic to the equator
latitudinal gradient
the length of the portion of resources that an organism uses
niche breadth
the diversity within a community
alpha diversity
large circular current in the middle of the ocean
gyre
a term that refers to diversity between communities
beta diversity
the general pattern of increase in species richness with increasing area of observation
species-area relationship
the developers of the equilibrium theory of island biogeography
MacArthur and Wilson
the theory that local species diversity is maximized when ecological disturbance is neither too rare nor too frequent
intermediate disturbance hypothesis
the model to obtain a quantitative estimate of biological variability that can be used to compare biological entities in space or in time
Shannon-Weaver diversity index
the theory where enrichment destabilizes predator–prey systems, causing species extinction
paradox of enrichment
an area with an uneven distribution of environmental characteristics
spatial heterogeneity
