ess test 2.1 and 2.2

Ecology

the study of living/nonliving parts of an ecosystem that interact within it

Levels of ecological organization

biosphere, biome, ecosystem, community, population, individual

Biosphere

an ecological system composed of individuals, populations, communities, and ecosystems

Biome

large, major habitat for a community of flora and fauna

Ecosystem

the organisms and their physical environment, and the interactions between the living and nonliving components within them

Community

a group of two or more populations of species living in the same area at the same time

Population

a group of organisms of the same species living in the same area at the same time

Individual

a singular organism

Species

a group of organisms that can interbreed and produce fertile offspring (i.e. the biological species concept)

binomial nomenclature

two-part name

the first part is the genus

the second part is the name specific to the species

- italicized when typed, underlined when written

clade

a taxonomic group which contains one ancestor and all its descendants

Habitat

the location in which a community, species, population, or organism lives

Niche

the abiotic and biotic conditions + resources upon which the organisms depend on

ecological niche

the role of a species in an ecosystem

Abiotic factors

non-living physical factors that may influence organisms

Temp

Light intensity

pH

DO

Soil texture

Turbidity

Biotic factors

the living components of an ecosystem like the organisms, their interactions, etc. (every organism in an ecosystem affects others and is affected by others)

Types of interaction

competition, predation, herbivory, parasitism, mutualism, disease

Competition

since resources are limited, species must compete for essentials such as food, water, space, light, and mates

- drives natural selection, population dynamics, and community structure

- 2 types: intraspecific and interspecific

Intraspecific Competition

members of the same species contend for resources and essentials

- when population numbers are small, there's little competition, plenty of resources, and population growth

- gulls compete for nesting sites and food

Result of intraspecific competition

as the population increases, there's more competition and resources become limiting factors, the population growth slows and stabilizes at the carrying capacities

- manifests in territoriality (organisms secure areas to get resources) and natural selection (better-adapted individuals are able to reproduce)

Interspecific Competition

members of different species contend for resources and essentials

- when niches overlap, both species use similar resources

- weed species overrun a garden, pushing out original domestic plants

Result of interspecific competition

the two species could either balance by dividing resources or occupying different areas OR one species could "win" and force the other species out (e.g. weeds beating nice plants in a yard)

- no two species can occupy the same niche in the same habitat

predator

a consumer that preys on animals

prey

the animals a predator eats

carnivores

consumers that eat other animals

Predation

predator kills and eats prey

- lynx hunts and eats hare

herbivore

consumers that eat plants

Herbivory

an animal (herbivore) eats green plants

- caterpillar feeds on milkweed leaves

parasite

live on or in living hosts and get their food from the hosts

Parasitism

a parasite lives in or on a host, getting food from it

- cuckoo lays eggs in warbler nest; warbler raises cuckoo chick

Mutualism

both species benefit from the relationship

- bacteria fix nitrogen for plant; plant supplies sugars

scavenger

mostly eat decaying biomass and are usually carnivores

Disease

pathogens cause disease, harming hosts

- virus kills rabbits; over time, both evolve toward stable coexistence

limiting factors

factors in an ecosystem that limit the population size, slowing growth as it reaches carrying capacity

- can be biotic or abiotic

carrying capacity (K)

the maximum number of a species that can be sustainability supported in an area

- determined by competition for limited resources

- fluctuates as conditions change

how humans have eliminated limiting factors

reduced natural predation

technological advances

agricultural revolution

broad and changing niche

density-dependent factors

decrease growth rate as population density increases (like negative feedback), pushes pop. back to K

competition: as a population grows, competition for limited resources intensifies

predation: dense populations are easier targets for predators

diseases and parasites: in crowded conditions, diseases spread more easily and deaths occur

waste accumulation: waste products can harm dense populations

density-independent factors

can impact populations the same way regardless of size

- extreme temperatures, wildfires, floods

j-curves

exponential growth, has no limiting factors (J on a graph)

"Boom and bust" because the population grows exponentially and then collapses suddenly (called a dieback)

S-curves

logistic growth, has limiting factors (S on a graph)

- although S-curves are closer to reality, j and S-curves are both idealized, there could be a lot more population fluctuation around the carrying capacity

environmental resistance

the area between what could be exponential growth and the S-curve

keystone species

A species that influences the survival of many other species in an ecosystem

sampling assumptions

the sample is representative of the whole population

enough samples are taken for accuracy

sampling is unbiased (random, not selective)

sampling for non-mobile organisms

do percentage cover or percentage frequency

Percentage cover

estimates the proportion of the ground area covered by a species

- used when individuals are too numerous to count (e.g. grasses, mosses)

Percentage frequency

measures how often a species appears in sample plots

- indicates distribution rather than exact density

Transects

samples taken at fixed intervals and set up along an environmental gradient

Line transect

measured line is randomly placed across the area in the direction of an environmental gradient; all species touching the line are recorded

- presence/absence along line

Belt transects

transect line is laid out and a quadrant is placed at each survey interval, samples are identified and abundance is estimated

- slow moving animals (limpets, barnacles, snails) are collected, identified, then released

- plants an percent coverage is estimated

Quadrats

counts all individuals within a small frame, used for population density

1. Randomly place quadrats in the study area

2. Count all individuals of each species

3. Calculate population density (N/m²)

considerations for quadrats

Larger quadrats → broader coverage, but less precision

Smaller quadrats → more precision, but may not represent area well

Always think about organism size and total area when deciding quadrat number and size

Lincoln Index

n1 = number caught and marked first sample

n2 = number caught second sample

nm = number marked on second sample

Assumptions of Lincoln Index

the population of organisms must be closed, with no exchanges w/ outside populations

the time between samples must be small compared to the life span

the marked organisms mix completely with the rest

equal chance of capturing marked and unmarked individuals upon second capturing

sources of error for the Lincoln Index

emigration & immigration

natural disaster or disturbance

"trap happy" (free shelter and food yay let's go get captured)

"trap shy" (scary scary people run away)

organisms did not have enough time to mix

animals lost their marks

habitat

the location in which a community, species, population or organism lives

Planetary boundaries

human activity has pushed biosphere integrity past safe limits

evidence: extinction rates far above natural background levels

First law of thermodynamics

the principle of conservation of energy: as energy flows through ecosystems, it can be transformed from one form to another but cannot be created or destroyed; the total energy in any isolated system is constant

cellular respiration

the process by which glucose is broken down to release energy for living processes

- needed to release energy for living processes

- all organisms respire, even autotrophs

entropy

a measure of the disorder of a system

- much energy produced in respiration is heat energy, cannot be transformed back into chemical energy and is lost

living processes

MRS GREN (movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition)

Photosynthesis

the process by which organisms make their own food from water and carbon dioxide using energy from sunlight

- produces the raw material for making biomass; animals are totally dependent on the chemicals produced by plants

processes for photosynthesis

- in chloroplasts, the energy of sunlight is used to split water and combine it with carbon dioxide to make food (glucose)

- water reaches the leaves of plants from the roots by transpiration

- the byproduct of photosynthesis is oxygen, which is used in aerobic respiration

compensation point

when all the carbon dioxide that plants produce in respiration is used up in photosynthesis, the rates of respiration and photosynthesis are equal and there is no net release of either oxygen or carbon dioxide

producer

makes its own food by photosynthesis

photoautotroph

does photosynthesis, gets energy from light

heterotroph

organism that obtains energy from the foods it consumes

consumer

gains its food from other organisms

herbivore

carnivore

omnivore

saprotroph

an organism that feeds on dead organic material

- decomposers and detritivores

decomposer

external digesters, releases enzymes to break down dead organic matter

- bacteria and fungi

detritivore

organism that feeds on plant and animal remains and other dead matter

- snails, slugs, maggots, vultures

trophic level

the position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains

second law of thermodynamics

as energy is transferred or transformed in a system, it is degraded to a less useful form of energy such as heat energy and entropy increases

efficiency

the useful energy or work produced by a process divided by the amount of energy consumed during the process

efficiency of transfer between two trophic levels =

amount of biomass transferred / amount of biomass available * 100

Energy =

Work + Heat

rule of 10

only about 10% of energy is transferred from one trophic level to the next

- greater losses at higher trophic levels due to more energy used for life processes/survival

reasons for inefficiencies in transfers of energy between trophic levels

not everything is eaten

digestion is inefficient

heat is lost in respiration

some energy assimilated is used in reproduction and other life processes

gross productivity (GP)

the total gain in biomass by an organism

net productivity (NP)

the amount of energy remaining after losses due to cellular respiration

- this goes into biomass

NPP (net primary productivity)

= GPP - R (respiratory loss)

- this accounts for respiratory loss

NSP (net second productivity)

= GSP - R

maximum sustainable yield

the net productivity of any organism or trophic level is that can be harvested without diminishing the availability for the future

biomass

the quantity of dry organic material in an organism, population, or particular trophic level in an ecosystem

= mass of each individual x number of individuals

determining biomass

measure dry mass (units are g m^-2 or Mg ha^-1)

- Water is a main component and can be removed through drying (lots of water weight)

Ecological pyramids

graphical models of the quantitative differences between amounts of living material stored at each trophic level of a food chain

pyramid of numbers

shows the number of organisms at each trophic level in a food chain at one time (standing crop)

advantages of pyramids of numbers

- simple, easy method of giving an overview

- good for comparing changes in population numbers with time or season

disadvantages of pyramids of numbers

- all organisms are included, regardless of their size, so a pyramid based on an oak tree is inverted

- doesn't allow for juveniles or immature forms

- numbers can be too great to represent accurately

pyramid of biomass

contains the biomass at each trophic level

- exception: phytoplankton, since they reproduce fast but are only available in small amounts at any one time

advantages of pyramids of biomass

overcome some of the problems of pyramids of numbers

disadvantages of pyramids of biomass

- only use samples from populations, so impossible to measure biomass exactly

- organisms must be killed to measure dry mass

- time of year at which biomass is measured affects the result

pyramid of energy (productivity)

shows the rate of flow of energy or biomass through each trophic level, shows it being generated and available as food to the next trophic level during a fixed period of time

productivity

rates of flow, whereas biomass values are stores existing at one particular time

advantages of pyramids of energy

- allow for rate of production over time

- allow comparison of different ecosystems

- can add solar radiation input

- never have inverted pyramids of energy

disadvantages of pyramids of energy

- need to measure growth and reproduction over time

- still have issues of consumers at more than one trophic level and where to put decomposers and detritivores

biocides

substances or microorganisms that destroy, deter or render harmless living things

bioaccumulation

the buildup of nonbiodegradable pollutants within an organism or trophic level because they cannot be broken down

biomagnification

the increasing concentration of non-biodegradable pollutants along a food chain

- bioaccumulation causes biomagnification*, decrease in biomass and energy means more concentrated at the top

pesticides

chemicals that kill pests, may also kill non-target organisms

human activity's effects on ecosystems

- biomass is lost to ecosystems when we build on land, grow crops, and cut down trees

- deforestation means less photosynthesis so less of the sun's energy is captured and turned into chemical energy

- solar farms can capture some sun energy but efficiency is about 20% at best