General Ecology Exam 3

introduced species

a species that is introduced to a region of the world where it has not historically existed

invasive species

an introduced species that spreads rapidly and has negative effects on other species, human recreation, or human economies

mesopredators

relatively small carnivores that consume herbivores

top predators

predators that typically consume both herbivores and mesopredators

Lotka-Volterra model

a model of predator-prey interactions that incorporates oscillations in the abundances of predator and prey populations and shows predator numbers lagging behind those of their prey

equilibrium isocline

the population size of one species that causes the population of another species to be stable

joint equilibrium point

the point at which the equilibrium isoclines for predator and prey populations cross

joint population trajectory

the simultaneous trajectory of predator and prey populations

functional response

the relationship between the density of prey and an individual predator's rate of food consumption

type I functional response

a functional response in which a predator's rate of prey consumption increases in a linear fashion with an increase in prey density until satiation occurs

Type II functional response

a functional response in which a predator's rate of prey consumption begins to slow down as prey density increases and then plateaus when satiation occurs

type III functional response

a functional response in which a predator exhibits low prey consumption under low prey densities, rapid consumption under moderate prey densities, and slowing prey consumption under high prey densities

numerical response

a change in the number of predators through population growth or population movement due to immigration or emigration

crypsis

camouflage that either allows an individual to match its environment or breaks up the outline of an individual to blend in better with the background environment

warning coloration

a strategy in which distastefulness evolves in association with very conspicuous colors and patterns

Batesian mimicry

when palatable species evolve warning coloration that resembles unpalatable species

mullerian mimicry

when several unpalatable species evolve a similar pattern of warning coloration

coevolution

when two or more species affect each others evolution

generalist

a species that interacts with many other species

specialist

a species that interacts with one other species or a few closely related species

obligate mutualists

two species that provide fitness benefits to each other and require each other to persist

facultative mutualists

two species that provide fitness benefits to each other but whose interaction is not critical to the persistence of either species

mycorrhizal fungi

fungi that surround plant roots and help plants obtain water and minerals

endomycorrhizal fungi

fungi characterized by hyphae threads that extend far out into the soil and penetrate root cells between the cell wall and the cell membrane

arbuscular mycorrhizal fungi

a type of endomycorrhizal fungi that infects a tremendous number of plants, including many trees and grasses

ectomycorrhizal fungi

fungi characterized by hyphae that surround the roots of plants and enter between root cells but rarely enter the cells

endophytic fungi

fungi that live inside a plant's tissues

infection resistance

the ability of a host to prevent an infection from occurring

infection tolerance

the ability of a host to minimize the harm once and infection has occurred

parasite load

the number of parasites of a given species that an individual host can harbor

ectoparasite

a parasite that lives on the outside of an organism

endoparasite

a parasite that lives inside an organism

emerging infectious disease

a disease that is newly discovered or has been rare and then suddenly increases in occurance

horizontal transmission

when a parasite moves between individuals other than parents and their offspring

vector

an organism that a parasite uses to disperse from one host to another

vertical transmission

when a parasite is transmitted from a parent to its offspring

reservoir species

species that can carry a parasite but do not succumb to the disease that the parasite causes in other species

SIR model

the simplest model of infectious disease transmission that incorporates immunity

ecotone

a boundary created by sharp changes in environmental conditions over a relatively short distance, accompanied by a major change in the composition of species

interdependent communities

communities in which species depend on each other to exist

independent communities

communities in which species do not depend on each other to exist

species richness

the number of species in a community

relative abundance

the proportion of individuals in a community represented by each species

log-normal distribution

a normal, or bell-shaped, distribution that uses a logarithmic scale on the x-axis

rank-abundance curve

a curve that plots the relative abundance of each species in a community in rank order from the most abundant species to the least abundant species

species evenness

a comparison of the relative abundance of each species in a community

Simpson's index

a measurement of species diversity with a range of 1-S

Shannon's index

a measurement of species diversity with a range of 0-ln(S)

keystone species

a species that substantially affects the structure of communities despite the fact that individuals of the species might not be particularly numerous

intermediate disturbance hypothesis

the hypothesis that more species are present in a community that occasionally experiences disturbances than in a community that experiences frequent or rare disturbances

food chain

a linear representation of how different species in a community feed on each other

food web

a complex and realistic representation of how species feed on each other in a community

trophic level

a level in a food chain or food web of an ecosystem

primary consumer

a species that eats producers

secondary consumer

a species that eats primary consumers

tertiary consumer

a species that eats secondary consumers

omnivore

a species that feeds at several trophic levels

guild

within a given trophic level, a group of species that feeds on similar items

direct effect

an interaction between two species that does not involve other species

indirect effect

an interaction between two species that involves one or more intermediate species

trophic cascade

indirect effects in a community that are initiated by a predator

density-mediated indirect effect

an indirect effect caused by changes in the density of an intermediate species

trait-mediated indirect effect

an indirect effect caused by changes in the traits of an intermediate species

bottom-up control

when the abundances of trophic groups in nature are determines by the amount of energy available from the producers in a community

top-down control

when the abundance of trophic groups is determined by the existence of predators at the top of the food web

community stability

the ability of a community to maintain a particular structure

community resistance

the amount that a community changes when acted upon by some disturbance, such as the addition or removal of a species

community resilience

the time it takes after a disturbance for a community to return to its original state

alternative stable state

when a community is disturbed so much that the species composition and relative abundance of populations in the community change, and the new community structure is resistant to further change

succession

the process by which the species composition of a community changes over time

seral stage

each stage of community change during the process of succession

pioneer species

the earliest species to arrive at a site

climax community

the final serial stage in the process of succession

chronosequence

a sequence of communities that exist over time at a given location

primary succession

the development of communities in habitats that are initially devoid of plants and organic soil, such as sand dunes, lava flows, and bare rock

secondary succession

the development of communities in habitats that have been disturbed and include no plants but still contain an organic soil

facilitation

a mechanism of succession in which the presence of one species increases the probability that a second species can become established

inhibition

a mechanism of succession in which one species decreases the probability that a second species will become established

priority effect

when the arrival of one species at a site affects the subsequent colonization of other species

tolerance

a mechanism of succession in which the probability that a species can become established depends on its dispersal ability and its ability to persist under the physical conditions of the environment

transient climax community

a climax community that is not persistent

fire-maintained climax community

a successional stage that persists as the final serial stage due to periodic fires

grazer-maintained climax community

when a successional stage persists as the final serial stage due to intense grazing

protective behavior

escape, avoid, hide, startle, alarm call

protective morphology

structures or coloration for defense or deception

aposematism

warning coloration associated with a harmful, usually chemical, defense

quantitative chemical defense

amount present varies continuously

qualitative chemical defense

either present or absent

ambush predator

rely on stealth rather than speed (sit and wait or stalking)

cursorial predator

chase down prey using high speed or endurance

resource partitioning

sympatric speciation avoid competition by exploiting different resources

character displacement

herd immunity

when enough individuals in a population are immune to a disease such that the disease will not spread

ecotone

sharp boundary reflecting environmental change over a short distance and major change in composition of species