Final BIO 135

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population ecology

how organisms populations change over time, looking at birth/death and immigration/emigration

demography

human population ecology

population census

when every individual is counted in a population

population estimate

when population number is inferred

mark and recapture

sampling method best for migratory species

dispersion patterns

different ways organisms disperse themselves

clumped (dispersal patterns)

clumped (dispersal method)  

individuals in a population live in a specific area, particularly living around a limited resource

random (dispersal method)

individual’s spacing in a population is independent of others

uniform (dispersal method)

population is evenly spaced, often due to competition for resources

cohort life table

tracks organisms born around the same time, following from birth to death

static life table

records survival and reproductive rates of population at a specific point in time by counting individuals in age

age distribution

proportionate breakdown of individuals of different ages within a population

survivorship curves

graph that illustrates how individuals in a  population survive over time 

r species

lots and lots of babies, little energy raising the babies

k species

less babies, raise them for longer

net reproductive rate

number of young females will have in their lifetime

geometric rate of increase

rate of constant growth over specifc time period

per capita rate of increase

average rate at which population, increase or decrease per individual

birth/death rate

number of individual born or die in population (normally each year)

fecundity schedule

biological capacity for reproduction; the number of eggs an individual can produce

fecundity schedule

biological capacity for reproduction; the number of eggs an individual can produce

geometric population growth

population that increases at a constant rate of growth (lambda to the power of t) (bunnies in spring)

exponential population growth 

when population grows dramatically, constant reproduction

logistic population growth

model that describes population growth but slows down at carrying capacity

carrying capacity

the environment’s maximum sustainable population

population regulation

process by which factors limit the growth of a population

density dependent factors

biological influences that limit population growth based on dense population is packed together 

density independent factors

environmental influences that affect a population regardless of population size

competition

both individuals are negatively impacted

mutalism

both are positively impacted

example of competition

lion and hyena fighting for resources, energy used and risky for injury

example of mutalism

bees and flowers, flowers spreads genes, bees get food

predation

predator eats prey

example of predation

bat eats frog

commenalism

one is positively impacted, others not affected

example of commensalism

orchid growing on tree for structure, tree not affected

amensalism

one is negatively impacted, other is not affected

example of amenalism

sunflower struggles to grow in shade of a tree, tree not affected

neutralism

both not affected by the other

example of neutralism

2 insects living in the same area on 2 different plants

interference competition

direct interaction between individuals that can reduce the fitness of both

example of interference competition

aggressive territory defense, production of chemical toxins, reducing access to resources

exploitation competition

populations negatively affect one another through use of shared resources

interspecific competition

competition between individuals of 2 species

intraspecific competition

competition with members of own species (male vs male for a mate)

competitive exclusion principle

when 2 species are competing for limited resources one species will eventually eliminate the other

allopatric distributions

when a population splits due to a geographical barrier separating them

functional response

an increase in an animal’s feeding rate that occurs in response to an increase in prey availability 

community ecology

the study of how different species interact in a shared habitat

community structure

how habitat communities are organized based on the quantity of individuals and interactions between them

guild

species that rely on same resources

species richness

amount of different species

species evenness

how species are distributed

species-area curve

graph that plots quantity of species versus area of habitat

species diversity

the variety of species in an ecosystem measured by species

Shannon Wiener Index

measure of species diversity in a community

H’ value in Shannon Wiener Index

variable for species diversity

rank-abundance curve

plot relative abundance of species against rank in abundance

species accumulation curve

species richness increases with sampling effort

disturbance

discrete event in time that causes abrupt change in community structure

intermediate disturbance hypothesis

intermediate levels of disturbance promote higher diversity

if disturbance is too high

everything dies out

if disturbance too low

dominant species takes over competition

direct interaction in food web

between two species

example of direct interactions in food web

competition and predation

indirect interactions

a third species influences the interactions between two other ospecies

example of indirect interactions

trophic cascade

foundational species

dominant (high biomass) and influential to community

example of foundational species

tree or coral

keystone species

typically smaller organisms, low in quantity, that have disproportionately large effect on ecosystem

ecosystem ecologists study the flow of _____ through ecosystems

energy

primary producers

first level

primary consumers

herbivores, eat primary producers

secondary consumers

carnivores, eat the herbivores

tertriary consumers

eat the carnviores

photosynthesis equation

carbon, water, light = glucose, oxygen, stored energy

respiration equation

glucose, oxygen, stored energy = carbon dioxide, water, heat

gross primary production

total amount of primary production by all primary producers

net primary production

amount of biomass available to consumers; gross primary production minus respiration

secondary production

biomass production by consumers during some period of time

actual evapotranspiration (AET)

annual amount of water that evaporate and transpires off a landscape

AET and terrestrial primary production

terrestrial plants increase with actual evapotranspiration

aquatic primary production is limited by

nutrient availability

trophic cascade

effects of predators on prey can alter more than one trophic level

bottom-up controls

influences of physical and chemical factors on ecosystem

top-down controls

influences of consumers on ecoystems

what can increase terrestrial primary production

grazing by large mammals

why does grazing from large mammals increase primary production?

compensatory growth of grass, improved water balance

process of secondary production

ingestion - egestion - excretion - respiration

ecological efficiency

percentage of energy transferred from one trophic level to the one above

biomagnification

increasing concentration of toxic substances in organisms at each trophic level

eutrophication

excess nutrients leading to increased primary production

nutrient pool

amount of particular nutrient stored in portion of ecosystem

nutrient flux

moving nutrients between pools

nutrient sink

part of biosphere where a nutrient is absorbed faster than released

nutrient source

where a nutrient is released faster than it is absorbed

important nutrient molecules

phosphorus, nitrogen, carbon

sources of phosphororus

mineral deposits and marine sediments

sources of nitrogen

largest pool is in the atmosphere