living things and theliving things and the environment •ecosystem: –all the living and nonliving...

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Science 7

ENVIRONMENTAL SCIENCE

Populations and Communities

Science 7

LIVING THINGS AND THE

ENVIRONMENT

• Ecosystem:

– All the living and nonliving things that interact in a particular area

– An organism obtains food, water, shelter, and other things it needs to live, grow and reproduce from its surroundings

– Ecosystems may contain many different habitats

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LIVING THINGS AND THE

ENVIRONMENT

• Habitat:

– The place and organism

lives and obtains all the

things it needs to survive

– Example:

• Prairie Dog

• Needs:

– Food

– Water

– Shelter

– Etc.

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LIVING THINGS AND THEIR

ENVIRONMENT

• Biotic Factors:

– The living parts of any

ecosystem

– Example: Prairie Dogs

• Hawks

• Ferrets

• Badgers

• Eagles

• Grass

• Plants

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ENVIRONMENT

• Abiotic Factors:

– Water:• All living things require water for survival

• Your body is 65% water

• A watermelon is 95% water

• Plants need water for photosynthesis for food and oxygen production

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ENVIRONMENT

• Abiotic Factors con’t

– Sunlight:

• Necessary for

photosynthesis

• Organisms which

use the sun form

the base of the

food chain

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ENVIRONMENT

• Abiotic Factors Con’t

– Oxygen:

• Necessary for most

living things

• Used by animals

for cellular

respiration

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ENVIRONMENT


– Temperature:

• The temperature of

an area determines

the type of

organisms which

can live there

• Ex: Polar Bears do

not live in the

tropics

• Ex: piranha’s don’t

live in the arctic

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ENVIRONMENT


– Soil:

• Mixture of rock

fragments, humus

(nutrients),

minerals, air, and

water

• Soil type dictates

flora in an area

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ENVIRONMENT

•Populations:

– All the members of one species in a particular area

– Ex: the number of students in this class

•Communities:

– All the different populations which live in an area

– Ex: all the animals in the Seneca Park Zoo

– Ex: all the animals in a forest

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DETERMINING POPULATION SIZE

•There are several methods of determining

population size

• 1. Direct Observation:

– Actually counting, one by one, all of the members of

a population

– Ex: counting all the elephants in a Kenyan valley

– Ex: counting all the Robins in your backyard

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•2. Indirect Observation

– If members of a population are either small or hard

to find, counting their tracks or signs of life can give

an estimate of population size

– Ex: counting mud swallow nests instead of the birds

– Ex: counting spittle bug nests rather than the bugs

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•3. Sampling

– In most cases you cannot count every member of the

population

– Sampling allows a researcher to count the number of

organisms in a small area and multiply to find the

number of organisms in a large area

– If there are 25 deer in a 10 acre by 10 acre area, and

the forest is 100 times that size, there are

approximately 2500 deer in the whole forest

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•4. Mark and Recapture Studies

– Researchers capture, tag and release a group of

animals in the environment

– Later, they capture another group of organisms in

the same area.

– If about ½ those caught are marked, then the first

group represented about ½ the population for that

species.

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CHANGES IN POPULATION SIZE

•Populations change in size when new members enter the population or when members leave the population

• Birth Rate:

– The number of births in a population in a certain amount of time

•Death Rate:

– The number of deaths in a population in a certain amount of time

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• Immigration and Emigration:

– Immigration refers to the organisms which move into

the population

– Emigration refers to the organisms which move out

of the population

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POPULATION LIMITING FACTORS

•A limiting factor is an environmental factor

that prevents a population from increasing

• They determine the “carrying capacity”

of the environment

– Carrying Capacity:

• The largest population of a particular

organism that the environment can

support

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• Food:

– Organisms require food to

survive

– When food is scarce, it

becomes a limiting factor

– If the environment cannot

provide enough food for a

population, individuals

will be culled

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• Space:

– Organisms require space to exist and reproduce

– If a bird doesn’t have room to nest, it will not reproduce, thus slowing population growth

– Plants need room to capture sunlight, if large trees block the sun, small plants will not thrive under them

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• Weather:

– Temperature and precipitation limit population growth

– Ex: cold weather kills off insects limiting the population

– Ex: frost or snow can ruin a citrus crop

– Ex: an early frost can kill off your garden and the limit vegetable population

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HOMEWORK

•Page 28

•Numbers 1-5

• Use COMPLETE SENTENCES !!!!!!!

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ADAPTING TO THE ENVIRONMENT

• Natural Selection:

– the way that changes which make organisms better suited to

their environments occur

• Adaptations:

– The behavior and physical characteristics of a species that

allows it to survive successfully in the environment

• Niche:

– An organism’s role or how it makes a living

– Type of food, how it gets its food, what critters use the

organism for food

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ORGANISM INTERACTIONS

•Competition:

– The struggle between organisms to survive in a

habitat with limited resources

– Limited amounts of food, water, and shelter cause

organisms to be in conflict with each other

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ORGANISM INTERACTIONS

•Predation:

– When one organism kills and eats another

• Predator:

– Organism doing the killing

• Prey:

– Organism being killed and eaten

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EFFECT OF PREDATION ON A

POPULATION

•An increase in predation, decreases the

population size

• A decrease in predation, increases the

population size

– Ex: Moose and Wolves on Isle Royale, in Lake

Superior

• Moose pop. rose, Wolf pop. Rose

• Moose pop. fell due to predation, wolf

pop. fell due to lack of prey

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SYMBIOSIS

•A close relationship between two species

that benefits at least one of them.

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SYMBIOTIC RELATIONSHIPS

•Mutualism:

– A relationship where BOTH species benefit

– Ex:

• Honey Bees and Dandelions

– Honey bees use nectar for food, and dandelions get their

pollen spread from plant to plant

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SYMBIOTIC RELATIONSHIPS•Commensalisms:

– A relationship in which one species benefits and the

other is neither helped nor harmed

– Ex:

• Robins building their nest in a maple tree

– However: commensalism is rare in nature since one

or both of the organisms involved are either helped

or harmed a little

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SYMBIOTIC RELATIONSHIPS•Parasitism:

– One organism lives on or inside another; thus

harming it

– Parasite:

• The organism that benefits; lives on or in

another organism

– Host:

• The organism that is harmed; is fed on

by the parasite

• Usually not killed because then the

parasite loses its food source

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SYMBIOTIC RELATIONSHIPS

•Parasitism Example:

– Deer Tick

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HOMEWORK

•Page 38

•Questions 1-5

•Complete Sentences!!!!!!!

Science 7

CHAPTER 1 TEST

•Populations

•Communities

• Biotic and Abiotic Factors

• Population Dynamics

• Limiting Factors

• Adaptations

• Interactions between Organisms

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ENVIRONMENTAL SCIENCE

Chapter 2

Ecosystems and Biomes

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ENERGY FLOW IN ECOSYSTEMS

•Producers:

– Organism that can make its own food

– These organisms are generally plants

– Means of energy production is primarily, but not

always photosynthesis

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• Consumers:

– Organisms which obtain energy by consuming other organisms

– Herbivores:• Consumers that eat plants

– Carnivores:• Consumers that eat only other animals

– Omnivores:• Consumers that eat both plants and animals

– Scavengers:• Carnivore that feeds on dead, decaying organisms

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• Decomposers:

– Organisms that break

down wastes and dead

organisms to return raw

materials to the

environment; RECYCLERS

• Fungi:

– Molds and mushrooms

• Bacteria:

– Single celled organisms

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FOOD CHAINS AND WEBS

• Food Chains:

– A series of events

in which ONEorganism eats

another and

obtains energy

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FOOD CHAINS AND WEBS

• Food Webs:

– 2 or more overlapping food chains in an

ecosystem

– How 2 or more organisms

interact with their

environment in terms of

energy transfer

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ENERGY PYRAMIDS

• A diagram that shows the amount of energy that moves from one feeding level to another in a food web– Most energy is available at the producer level

– At each higher level of the pyramid, less energy is available than at the level below

– Only about 10% of energy from one level is transferred to the next level

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HOMEWORK

•Page 50

•Numbers 1-5

•Complete Sentences!!!!!

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CYCLES OF MATTER

• Water Cycle:

– A continuous process by which water moves from earth’s surface to the atmosphere and then back

– Evaporation:• Process where liquid water, gains heat, and becomes water vapor (gas)

– Condensation:• The process where water vapor loses heat, and becomes a liquid water droplets to form clouds

– Precipitation:• Any form of water which falls to earth from the atmosphere

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THE WATER CYCLE

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THE CARBON/OXYGEN CYCLE

• These two cycles are linked– Produces use carbon from carbon dioxide to produce carbon-containing molecules and release oxygen

– Consumers eat carbon-containing compounds for energy and breath oxygen; releasing carbon dioxide as a byproduct; for use by producers

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THE NITROGEN CYCLE

•How Nitrogen moves through the

environment

– Plants “fix” or capture “free” Nitrogen from the air

– Consumers eat N-compounds in plants

– Animal Waste and plant remains decompose;

bacteria release “Free” nitrogen back to the air

– Bacteria in roots of plants “Fix” the “Free” Nitrogen

into the plant again

– The Cycle Continues

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THE NITROGEN CYCLE

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HOMEWORK

•Page 55

•Questions # 1-5

•Complete Sentences

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BIOGEOGRAPHY

•The study of where organisms live

– Continental Drift:

• The slow movement of continents across

the earth’s surface

• Huge impact on biogeography

• Organisms were isolated from one

another and thus began to evolve in

different ways

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ORGANISM DISPERSAL

• the movement of

organisms from

one place to

another

• Example:

– Milkweed seed

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ORGANISM DISPERSAL

• Wind

– Plants and small

organisms need assistance

to move

– Wind spreads seeds,

spores of fungi, and tiny

spiders

Whirling Nut (Gyrocarpus)

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ORGANISM DISPERSAL

• Water:

– Water can transport

objects which float

– Ex: coconuts and leaves

– Insects and small animals

get a free ride to a new

home aboard floating

rafts

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ORGANISM DISPERSAL

• Other living things:

– organisms can be carried

from place to place by

animals which come into

contact with them

– Ex: ducks carry algae

from pond to pond

– Ex: birds carry seeds and

drop them in their waste

– Ex: dogs carry sticky seeds

from place to place in fur

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EXOTIC VS. NATIVE SPECIES

•Native Species:

– Species that naturally

evolved in an area

– Ex: Northern Pike in

Conesus Lake

• Exotic Species:

– Species carried into a new

location by people

– Ex: Zebra Mussels

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LIMITS TO SPECIES DISPERSAL

• Physical Barriers:

– Water, mountains, and

deserts can make it

difficult for organisms to

move from one area to

another

Mount

Everest

Pacific OceanScience 7


• Competition:

– When organisms enter a

new area, they must

compete for survival

resources

– To survive, they must find

a unique niche in which

to make a living

– If no niche is available,

the organism will die out

and dispersion will stop

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• Climate:

– Variation in climate serves

as a barrier to dispersal

– Organisms adapted to

warm, moist climates,

cannot survive in dry, cold

climates and visa versa

– This is why different

species are found at

different elevations in the

mountains

Science 7

HOMEWORK

•Page 59

•Numbers 1-5

•Complete sentences

Science 7

EARTH’S BIOMES

•Biome:

– A group of ecosystems with similar climate and

organisms

– Classified mainly by climate conditions-temperature

and rainfall-in an area

– Include:

• Rain Forest Biomes, Desert Biomes,

Grassland Biomes, Forest Biomes,

Tundra Biomes, Freshwater and marine

biomes,

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TROPICAL RAIN FOREST BIOME

• Warm regions close to

the equator

• Constant, warm

temps with high

rainfall rates

• As many as 300

different trees in a

100 m2 area

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TEMPERATE RAIN FOREST BIOME

• The Pacific Northwest

United States

• More than 300 cm of

rain a year

• Huge trees; cedars,

redwoods, Douglas

firs

• Cool, very wet

climate

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DESERT BIOME

• Receives less than 25 cm of precip. per year

• Scorching days and cold nights

• Cactus, tortoise, reptiles

Gobi

Desert,

Mongolia

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GRASSLAND BIOMES

• Grassland:

– 25-75 cm of precip. per year

– Grasses and other non-woody

plants

• Savannas:

– Up to 120 cm of precip. per

year

– Located closer to the equator-

hotter

– Populated by large herbivores,

scavengers, and large

carnivores

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DECIDUOUS FOREST BIOME

• Experience 4 seasons

• Deciduous Trees: lose

their leaves in winter

• Oak, maple, ash, etc.

trees

• At least 50cm of

precip. per year

• Many different

habitats

From:

nysparks.state.ny.us/parks/info.a

sp?parkID=12

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BOREAL FOREST (TIAGA) BIOME

• Northern, colder

climates

• Coniferous trees

(evergreens)

• Cool summers and

very cold winters

• Moose, bear,

porcupine, wolvesTaiga Woods-Denali National

Park; Alaska

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TUNDRA BIOME

• Very cold and very dry land biome

• Less than 25 cm precip. per year

• Mosses, grass, shrubs, caribou, insects, birds, fox, wolves, hares, and lichens

• Permafrost:

– Annually frozen soil

tundra near Churchill, Manitoba,

Canada

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FRESHWATER BIOME

• Many organisms make

their homes in water

• Much photosynthesis

takes place here near the

surface of the water

• Algae are common

producers

• Frogs, snails, fish,

salamanders, insects,

etc.

An unnamed lake at Acadia

National Park, Maine

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MARINE BIOME

• Contains 5 specific habitats

• Estuary Habitat:

– Where fresh and salt waters meet and mix

– Marsh grasses, algae, plants, water birds, crabs, worms, clams, oysters, and fish

– Breeding grounds for many organisms From: http://www.estuarylive.org/

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MARINE BIOMES

• Intertidal Zone:

– Shoreline between the highest high-tide line and the lowest low-tide line

– Barnacles, sea stars, crabs, mussels, worms, copepods, other rock dwellers

http://library.thinkquest.org/J002608/low_intertidal_

zone.html

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MARINE BIOMES

• Neritic Zone:

– Region of shallow water below the low-tide line

– Schools of fish, algae, coral reefs, crabs, etc.

– Extends to the continental shelf From: http://oceanworld.tamu.edu/students/coral/index.html

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MARINE BIOMES

• Surface Zone:

– Off-shore, Open ocean

water

– Algae carrying out

photosynthesis

– Major producer of oxygen

for the atmosphere

– Extends to depths of up to

100 meters of about 300

feet Blue-green algae from:

http://www.nrw.qld.gov.au/water/blue_green/blue_g

reen.htmlScience 7

MARINE BIOMES

• Deep (benthic) zone:

– Completely dark and very

cold

– A harsh environment to

survive in

– Giant squid,

bioluminescent fish, etc.

– Can only be reached with

a submersible

Science 7

HOMEWORK

•Page 73

•Questions 1-5

•Complete Sentences!!!

living things and theliving things and the environment •ecosystem: –all the living and nonliving...

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