Environmental Science Test 2

Important chemicals for living things

Carbon (C), Phosphorous (P), and Nitrogen (N)

Population

group of individuals of the same spp. inhabiting the same area

Natality

# of individuals added to the population through

reproduction over a particular time period

Mortality

# deaths in a population over a particular time period

natural rate of increase w/out migration

(birth rate - death rate)

birth rate

# individuals born / 1,000 individuals / year

Death rate

# people who die / 1,000 individuals / year

Immigration

movement of people into an area

emigration

movement of people out of an area

population change

(births + immigration)- (deaths + emigration)

sex ratio

relative # of males and females in a population

age distribution

number of individuals of each age in the population

age categories

pre-reproductive: 0-14

reproductive: 15-44

post-reproductive: 45+

survivorship curve

shows the proportion of individuals likely to survive to each age

3 types of survivorship curves

1. spp. w survival chances high to an old age

2. spp. w survival chances equal to among age classes

3. spp. w low survival chances in young

biotic potential

inherent reproductive capacity of a spp. (biological ability to produce offspring)

Carrying capacity (K)

Max # of individuals of a given spp. the environment can support.

As K is reached, resources decrease

Population size case study

reindeer on alaskan island, population grew then. crashed (Malthusian growth)

Malthusian catastrophe

population growth > ag production

Preventive vs. Positive (Natural)

Preventive: delay marriage or abstain from procreation based on lack of resources based on conscious decision.

Positive (Natural): an event, such as war/famine'/plague, that shortens the human life span

Replacement Rate

TFR of 2.1

3 major reasons for rapid decline in global fertility rate

1. empowerment of women

2. declining rates of child mortality

3. rising costs of bringing up children, with the decline of child labor

characteristics of life

1. has highly organized internal structure and organization

2. possesses characteristic types of DNA molecules in each cell

3. captures and transforms matter and energy from envr to supply needs of growth/reproduction/survival

4. maintains favorable internal conditions (homeostasis) despite external conditions

5. reproduce

6. adapts to external change

Aristotle’s definition of life

“…. by life we mean self-nutrition and growth”

source of all energy

the sun

• supplies energy for photosynthesis

• drives climate and weather systems

• powers the cycling of matter

ecology

study of relations between organisms and their natural environment, living and nonliving

ecosystem

biotic community and its abiotic environment, functioning as a system

habitat

space in which an organism lives, defined by the biological requirements of each particular organism

niche of an organism

functional role in habitat + interactions with other organisms 

limiting factors

any factors whose shortage or absence restricts species success.

• the envr condition that determines population size of an organism

• LF examples (trout in cool water w more O2)

patterns that all populations go through

• lag phase (pop is small)

• exponential growth phase (increase by fixed %)

• stable equilibrium phase (births = deaths)

• death phase (deaths > births)

symbiosis

one spp. is dependent on the other. at least one spp. derives benefit

3 kinds of symbiotic relationships

1. parasitism (parasite gains nourishment from another) (~50% of all organisms)

2. commensalism (one spp. is benefitted, other is neither benefitted nor harmed)

3. mutualism (both spp. benefit)

2 kinds of parasitism

1. ectoparasites: live on the host’s surface

2. endoparasites: live inside the body of the host

competition

two organisms are striving for the same limited resource

2 kinds of competition

1. intraspecific: competition between members of the same spp.

2. interspecific: competition between members of different spp.

Charles Darwin

• All nature is at war, one organism with another, or with external nature. Seeing the contented face of nature, this may at first well be doubted; but reflection will inevitably prove it to be true.” (opening of paper delivered to Linnean Society in 1858)

• “all organic beings are exposed to severe competition” and to “the universal struggle for life.”

Alfred Wallace

Plants and animals locked in “a struggle for existence, in which

the weakest and least perfectly organized must always

succumb.”

example of cooperation

herbivore population controlled by plant it eats

• example: CA quail and sagebrush

competitive exclusion principle

no 2 spp. can occupy same niche at the same time

resource partitioning

• food, water, habitat

• less competition between 2 spp.

• more niche specialization, less overlap 

• example: owls (nocturnal)/hawks (diurnal) - eat similar prey

predation

kind of interaction in which one animal kills/eats another

predator-prey dynamics

• can maintain stability, but can also cycle

• predators can over-eat prey

• prey pop goes up more quickly than predator pop

prey defenses: detection

• visual

• chemical

• auditory

• tactile

prey defenses: avoiding and surviving

• intimidation

• deception

• sacrificing body parts (autonomy)

• flight

• fighting back

• exuding foul tasting chemicals (eg. regal horned lizard)

prey defenses: camoflauge

blend into the background

prey defenses: mimicry

one spp. resembles another that possesses anti-predator traits (ex. stick insect)

prey defenses: warning! warning!

aposematic coloration: warning coloration (ex. poison dart frogs)

community

an assemblage of all interacting spp. of organisms in an area

ecosystem

a defined space in which interactions take place between a community, with all its complex interrelationships, and the physical environment

3 major categories of roles of organisms on ecosystems

1. producers (autotrophs)

2. consumers (heterotrophs)

3. decomposers

trophic level (“feeding level”)

1st level = producers

2nd level = primary (1) consumers

3rd level = secondary (2) consumers

4th level = tertiary (3) consumers

detritivores process detritus from all levels

how much energy is lost as heat as energy moves from one trophic level to the next

90%

biomass

weight of living material

10% rule

only 10% of food energy taken in by herbivore is passed on to carnivore

food chain

series of organisms occupying different trophic levels through which energy passes as a result of one organism consuming another

food web

series of multiple, overlapping food chains

biogeochemical cycles

organisms are composed of molecules and atoms that are cycled between living and non-living portions of an ecosystem

human impact on the Carbon Cycle

• burning fossil fuels takes C atoms that were removed temporarily from active, short-term C cycle and reintroduces them into the active cycle

• converting forests (long-term C storage) to agricultural land (short-term C storage) has greater amount of CO₂ in atmosphere

human impact on the Nitrogen Cycle

if too much N or P is applied as fertilizer, or if applied at the wrong time, much of the fetilizer is carried into aquatic ecosystems

succession

• concept that communities proceed through a series of recognizable, predictable changes in structure over time

• sequential replacement of a community’s flora by other species (primary and secondary)

• occurs bc establishment of new species modifies the environment

climax community

relatively stable, long-lasting community that is the result of succession

primary succession

no soil formation

secondary succession

Soil is present

• general pattern: annual weeds —> grasses —> perennial herbs —> shrubs —> trees

Biomes

• terrestrial climax communities with wide geographic distributions

• primary factor is climate

what is the difference between climate and weather?

• difference is a measure of time

• weather: conditions of the atmosphere over a short period of time

• climate: how the atmosphere “behaves” over relatively long periods of time

precipitation and temperature

two primary non-biological (abiotic) factors have major impacts on the kinds of climax communities that develop in any part of the world

temperate deciduous forest

• typical of eastern half of U.S.

• trees typically lose their leaves (deciduous)

tundra

• north of taiga

• very cold

• lacks trees and has permanently frozen subsurface soil (permafrost)

key environmental factors that shape aquatic ecosystems

• ability of sun’s rays to penetrate water

• depth of water

• nature of the bottom substrate

• water temp

• amount of dissolved salts

major aquatic ecosystems

• marine

• estuaries

• freshwater (lakes, ponds, streams, rivers, wetlands)

mangrove swamp ecosystems

tropical forest ecosystems that occupy shallow water near the shore and adjacent land

mangrove swamp- trees

trees tolerate high salt content

• exclude salts (red)

• excrete salt (black and white)

2 broad categories of freshwater ecosystems

• stationary water (lentic): lakes, ponds, and reservoirs

• running water (lotic = flowing) :streams, rivers

swamps

wetlands containing trees able to live in environments that are permanently flooded or flooded most of the year

marshes 

wetlands dominated by grasses and reeds

lake zones

• littoral zone: closest to shore, where plants grow

• limnetic zone: open water

• phytoplankton: photosynthesizing algae

• zooplankton: microscopic animals

biodiversity

a broad term used to describe the variation/different types of genes, species, and ecosystems in a region

extinction

the elimination of all the individuals of a particular species.

threatened species

any spp. that is likely to become an endangered spp. within the foreseeable future throughout all or a significant portion of its range

endangered species

any spp. that is in danger of extinction throughout all or a significant portion of its range

certain kinds of spp. that are more likely to go extinct than others:

• spp. with small, dispersed populations

• organisms in small, restricted areas, such as islands

• specialized organisms

• organisms at higher trophic levels

genetic diversity

the number of kinds of genes present in a population

what affects a population’s genetic diversity?

1. mutations (introduce altered genetic info into a pop by modifying current genes)

2. migration (allows movement of genes from one pop to another)

3. sexual reproduction (generates new genetic combos)

4. pop size

5. selective breeding

species richness

the number of different kinds of species in an area

ecosystem diversity

a measure of the number of kinds of ecosystems present in an area

ecosystem service

any positive benefit that wildlife or ecosystems provides to the people

4 major categories of services

1. provisioning

2. regulating

3. cultural

4. supporting

averaged recent estimate of economic value of ecosystems

$44 trillion 

2 major causes of past extinctions

• habitat loss

• fragmentation

threats to biodiversity

• typically, most productive natural ecosystems are the first to be modified by humans

deforestation

the process of destroying a forest, often for the purposes of fuel, building materials, or to clear land for farming

forest degredation

the thinning of tree density and the culling of biodiversity below an apparently protected canopy

big 4 commodities

palm oil, soy, cattle, wood products

overexploitation

humans harvest organisms faster than the organisms are able to reproduce (example: sturgeon)

What is the largest driver of deforestation?

beef

kuznet’s curve

as countrys get richer they can begin to care about stewardship

example of species suffering from poaching

rhinos

• big money in horns

• traditional medicinal

brazilian pepper

invasive plant species, environmental damage

endangered species act: year and main purpose

1973, designates species as threatened/endangered and gives U.S. government jurisdiction over them