AP Bio Unit 8: Ecology

ethology

study of how evolutionary processes shape inherited behaviors and the ways that animals response to specific stimuli

proximate cause

how a behavior occurs or how its modified (what was the stimulus to cause this behavior/”nurture”)

ultimate cause

why a behavior occurs in context of natural selection (how does the behavior help survive and reproduce/”nature”)

fixed action patterns (FAPs)

a sequence of unlearned acts directly linked to a stimulus, unchangeable actions, carried out to completion, triggered by external cue (goose retrieving egg)

migration

regular long distance change in location triggered by environmental cues

signal

a stimulus generated and transmitted from one animal to another (animal communication)

pheromones

chemicals emitted by members of the same species

stimulus response chains

when a response to a stimulus serves as the next stimulus for a behavior (ex: animal courtships)

directed movements

movements towards or away from a stimulus

kinesis

change in the rate of movement or the frequency of turning movements in response to a stimulus (nondirectional) ex: lice moving fast in a dry area to get out of it

taxis

directional movement towards (positive) or away from (negative) a stimulus

phototaxis

movement in response to light

chemotaxis

movement in response to chemical signals

geotaxis

movement in response to gravity

learning

the modification of behavior based on specific experiences

imprinting

longlasting behavioral response to an individual during a sensitive period of development (imprints on the first individual they see)

spatial learning

establishing memories based on spatial structures of the animal’s surroundings (ex: birds finding hidden nests)

associative learning

ability to associate one environmental feature with another (ex: associating butterflies with bad taste)

social learning

learning through observations and imitations of observed behaviors (ex: chimps breaking open nuts)

altruism

selfless behavior that reduces the individual fitness but increases the population’s fitness (ex: workers in ant colonies)

phototropism

directional response that allows plants to grow towards (and in some cases away from) a source of light

photoperiodism

allows plants to develop in response to day length, plants flower only at certain times of year

ecosystem

the sum of all the organisms living in a given area and the abiotic factors they interact with

first law of thermodynamics

energy can neither be created nor destroyed, only transferred

second law of thermodynamics

exchanges of energy increase the universe’s entropy (randomness)

law of conservation of mass

chemical elements are continually recycled in the environment

metabolic rate

total amount of energy an animal uses in a unit of time (higher in smaller organisms, lower in larger organisms)

endotherms

warm blooded, use thermal energy from metabolism to maintain body temperature

ectotherms

cold blooded, use external sources to regulate body temperature

autotrophs/primary producers

use light energy to synthesize organic compounds

chemosynthetic

produce food using the energy created by chemical reactions (ex: archaea)

heterotrophs

rely on autotrophs because they can’t make their own food

primary consumers

herbivores

secondary consumers

carnivores eating herbivores

tertiary consumers

carnivores eating carnivores

decomposers

get energy from detritus (nonliving organic material)

food chain

transfer of food energy up the trophic levels

food web

linked food chains

biogeochemical cycles

nutrient cycles containing biotic and abiotic factors (ex: water and nitrogen cycles)

water cycle

essential for all life, influences the rate of ecosystem processes

carbon cycle

essential for life, required in the formation of organic compounds

nitrogen cycle

important for the formation of amino acids, proteins, and nucleic acids

phosphorus cycle

important for the formation of nucleic acids, phospholipids, and ATP

primary production

amount of light energy converted to chemical energy

gross primary production (GPP)

total primary production in an ecosystem

net primary production (NPP)

GPP minus (-) the energy used by the primary producers for respiration

secondary production

amount of chemical energy in a consumer’s food that’s converted to new biomass

transfer of energy between trophic levels

~ 10%

demography

study of the vital statistics of populations and how they change over time

life table

age-specific summary of the survival pattern of a population (survivorship curve)

Type I curve

low death rate during early/middle life, high death rate later in life

Type II curve

constant death rate over the organism’s lifespan

Type III curve

high death rate early in life and lower death rate for those that survive early life

population

group of individuals of the same species living in an area

population ecology

analyzes the factors that affect population size and how/why it changes over time

density

number of individuals per unit area (counting and sampling)

dispersion

the pattern of spacing among individuals within a population

clumped dispersion

individuals gather in patches

uniform dispersion

evenly spaced individuals (can be due to territoriality)

random dispersion

unpredictable spacing of individuals (not common)

logistic growth model

per capita rate of increase approaches zero as the population size nears its carrying capacity

exponential growth model

a population living under ideal conditions, population grows at a constant rate, J curve

life history

the traits that affect an organism’s schedule of reproduction and survival: 1) when reproduction begins 2) how often the organism can reproduce 3) the number of offspring produced per reproductive episode

K-selection (density-dependent selection)

selection for life history traits that are sensitive to population density (seen in high density populations close to carrying capacity)

R-selected (density-independent selection)

selection for life history traits that maximize reproductive success (seen in low density populations with little competition)

density-dependent regulation

as a population increases, factors can slow or stop growth by decreasing birth rate and increasing death rate

density-independent regulation

factors that exert their influence on population size but the birth/death rate does not change (ex: natural disasters)

community

a group of populations of different species living closely and capable of interacting

habitat

a place or part of an ecosystem occupied by an organism

ecological niche

the role and position a species has in its environment

fundamental niche

the niche potentially occupied by the species if there were no limiting factors (predators, competitors, etc.)

realized niche

the portion of the fundamental niche the species actually occupies

interspecific interactions

interactions of individuals from one species with individuals of another species

symbiosis

when 2+ species live in direct contact with one another

parasitism

one organism derives nourishment from a host (+ / -)

mutualism

both organisms benefit from the relationship (+ / +)

commensalism

one organism benefits and the other is neither harmed nor benefited (+ / 0)

facilitation

one species has a positive effect on the survival and reproduction of another without intimate association of symbiosis (+ / + or +/0) (ex: plants)

biodiversity

variety of different organisms within a community, boosts productivity and resilience

species richness

the number of different species in a community

relative abundance

the proportion each species represents of all the individuals in the community

competition

relationship where individuals of different species compete for limited resources (-/-)

competitive exclusion principle

2 species competing for the same resource can’t coexist permanently

niche partitioning

natural selection drives competing species into different patterns of resource use or different niche

predation

relationship where one species kills and eats another (-/+)

cryptic coloration

camouflage

Batesian mimicry

harmless species mimics a harmful one

Mullerian mimicry

2+ bad tasting species evolve to look similar, allowing predators to learn to avoid all of them more quickly by associating a single warning pattern with a negative experience

herbivory

relationship where one organism eats part of a plant or alga (-/+)

keystone species

not usually abundant, but other species in an ecosystem rely on them because of their important niche

Simpson’s diversity index

calculate diversity based on species richness and relative abundance (high index=high biodiversity)

invasive species

nonnative species that occupy a wide range of habitats and competitively exclude native species from those habitats

overharvesting

organisms are harvested faster than their population can rebound

disturbance

event that changes a community by removing organisms from it or altering resource availability

ecological succession

gradual process by which the species composition of a community changes and develops over time after a disturbance

primary succession

a series of changes on an entirely new (previously lifeless) habitat that has not been colonized

secondary succession

a series of changes that clears an existing community but leaves the soil intact

global change

alterations to climate, atmospheric chemistry, and ecological systems that reduce the capacity of Earth to sustain life

biogeographical factors

large scale factors that contribute to a range of diversity observed

latitude

species are more diverse in tropics than at the poles due to climate