Ecology Vocab - Chapter 39 to 44

habituation

learning not to respond to a repeated neutral stimulus

imprinting

learning that can occur only during a specific interval in an animal’s life

instinctive behavior

an innate response to a simple stimulus

learned behavior

behavior that is modified by experience

pheromone

chemical that serves as a communication signal between members of an animal species

lek

of some birds, a communal mating display area for males

sexual dimorphism

distinct male and female body forms

territory

area an animal or group occupies and defends

dominance hierarchy

social system in which resources and mating opportunities are unequally distributed within a group

selfish herd

temporary group that forms when individuals cluster to minimize their individual risk of predations

social animal

animal that lives in a multigenerational group in which members, who are usually relatives, cooperate in some tasks

altruistic behavior

behavior that benefits others at the expense of the individual

eusocial animal

animal that lives in a multigenerational group in which many sterile workers cooperate in all tasks essential to the group’s welfare, while a few members of the group produce offspring

theory of inclusive fitness

alleles associated with altruism can be advantageous if the expense of this behavior to the altruist is outweighed by increases in the reproductive success of relatives

demographics

statistics that describe a population

ecology

study of interactions among organisms, and among organisms and their environment

mark-recapture sampling

method of estimating population size of mobile animals by marking individuals, releasing them, then checking the proportion of marks among individuals recaptured at a later time

plot sampling

using demographics observed in sample plots to estimate demographics of a population as a whole

population density

number of individuals per unit area

population distribution

location of population members relative to one another; clumped, uniformly dispersed, or randomly dispersed

population size

total number of individuals in a population

biotic potential

maximum possible growth rate under optimal conditions

emigration

movement of individuals out of a population

exponential growth

a population grows by a fixed percentage in successive time intervals; the size of each increase is determined by the current population size

immigration

movement of individuals into a population

per capita growth rate (r)

of a population, the change in individuals added over some time interval, divided by the number of individuals in the population

zero population growth

interval in which births equal deaths

carrying capacity (K)

maximum number of individuals of a species that a particular environment can sustain; can change over time

density-dependent limiting factor

factor that limits population growth and has a greater effect in dense populations; for example, competition for a limited resource

density-independent limiting factor

factor that limits population growth and arises regardless of population size; for example, a flood

intraspecific competition

competition for resources among members of the same species

logistic growth

a population grows exponentially at first, then growth slows as population size approaches the environment’s carrying capacity for that species

cohort

group of individuals born during the same interval

K-selection

selection that favors traits that allow their bearers to outcompete others for limited resources; occurs when a population is near its environment’s carrying capacity

life history

a set of traits related to growth, survival, and reproduction such as life span, age-specific mortality, age at first reproduction, and number of breeding events

r-selection

selection that favors traits that allow their bearers to produce the most offspring the most quickly; occurs when population density is low and resources are abundantsur

survivorship curve

graph showing how many members of a cohort remain alive over time

age structure

distribution of population members among various age categories

replacement fertility rate

number of children a woman must bear to replace herself with one daughter of reproductive age

reproductive base

of a population, members of the reproductive and pre-reproductive age categories

total fertility rate

expected number of children a women will bear over the course of a lifetime

demographic transition model

model describing the changes in human birth and death rates that occur as a region becomes industrialized

ecological footprint

area of Earth’s surface required to sustainably support a particular level of development and consumption

commensalism

species interaction that benefits one species and neither helps nor harms the other

community

all species that live in a particular area

habitat

type of environment in which a species typically lives

symbiosis

one species lives in or on another in a commensal mutualistic, or parasitic relationship

mutualism

species interaction that benefits body species

character displacement

as a result of competition between two species, the species become less similar in their resource requirements

competitive exclusion

process whereby two species compete for a limiting resource, and one drives the other to local extinction

ecological niche

all of a species’ requirements and roles in an ecosystem

interspecific competition

competition between members of two species

resource partitioning

evolutionary process whereby species become adapted in different ways to access different portions of a limited resource; allows species with similar needs to coexist

camouflage

coloration or body form that helps an organism blend in with its surroundings and escape detection

herbivory

an animal feeds on plants or plant parts

mimicry

an evolutionary pattern in which one species becomes more similar in appearance to another

predation

one species captures, kills, and eats another

biological pest control

use of a pest’s natural enemies to control its population size

brood parasitism

one egg-laying species benefits by having another raise its offspring

parasitism

relationship in which one species withdraws nutrients from another species, without immediately killing it

parasitoid

an insect that lays eggs in another insect, and whose young devour their host from the inside

indicator species

species whose presence and abundance in a community provides information about conditions in the community

intermediate disturbance hypothesis

species richness is greatest in communities with moderate levels of disturbance

pioneer species

species that can colonize a new habitat

primary succession

a new community becomes established in an area where there was previously no soil

secondary succession

a new community develops in a site where a community previously existed

exotic species

a species that evolved in one community and later became established in a different one

keystone species

a species that has a disproportionately large effect on community structure relative to its abundance

area effect

larger islands have more species than smalle ones

distance effect

islands close to a mainland have more species than those farther away

equilibrium model of island biogeography

model that predicts the number of species on an island based on the island’s area and distance from the mainland

consumer

organism that obtains energy and carbon by feeding on tissues, wastes, or remains of other organisms

decomposer

organism that feeds on biological remains and breaks organic material down into its inorganic subunits

detritivore

consumer that feeds on small bits of organic material

ecosystem

a biological community and its environment

food chain

description of who eats whom in one path of energy flow through an ecosystem

primary production

the rate at which an ecosystem’s producers capture and store energy

producer

an organism that obtains energy directly from the environment and carbon from inorganic sources; an autotroph

trophic level

position of an organism in a food chain

detrital food chain

food chain in which energy is transferred directly from producers to detritivores

food web

set of cross-connecting food chains

grazing food chain

food chain in which energy is transferred from producers to grazers (herbivores)

biogeochemical cycle

a nutrient moves among environmental reservoirs and into and out of food webs

aquifer

porous rock layer that holds some groundwater

groundwater

soil water and water in aquifers

runoff

water that flows over soil into streams

soil water

water between soil particles

water cycle

movement of water among Earth’s oceans, atmosphere, and the freshwater reservoirs on land

atmospheric cycle

biogeochemical cycle in which a gaseous form of an element plays a significant role

carbon cycle

movement of carbon, mainly between the oceans, atmosphere, and living organisms

global climate change

a rise in average temperature that is altering climate patterns around the world

greenhouse effect

warming of Earth’s lower atmosphere and surface as a result of heat trapped by greenhouse gases

denitrification

conversion of nitrates or nitrites to nitrogen gas

nitrification

conversion of ammonium to nitrate

nitrogen cycle

movement of nitrogen among the atmosphere, soil, and water, and into and out of food webs

nitrogen fixation

conversion of nitrogen has to ammonia

phosphorus cycle

movement of phosphorus among Earth’s rocks and waters, and into and out of food webs

sedimentary cycle

biochemical cycle in which the atmosphere plays little role and rocks are the major reservoir

bioaccumulation

the concentration of a chemical pollutant in the tissues of an organism rises over the course of the organism’s lifetime

biological magnification

a chemical pollutant becomes increasingly concentrated as it moves up through food chains