IB Biology Chapter 4 Ecology - PowerPoint Presentation

Slide1

IB Biology Chapter 4

EcologySlide2

Species ,communities, and ecosystems

Interdependence

of Living Organisms

1980-eruption @ Mt St. Helen’s-see p.172Slide3

What is a species?

Defined

as a

_____________________

Made up of organisms that-

Have similar physiological and morphological (

ie. Size and shape of an organism and/or its parts) characteristics that can be observed or measuredHave the ability to interbreed and produce fertile offspringAre genetically distinct from other organismsHave a common phylogeny(ie.family tree)

That can interbreed and produce fertile offspringSlide4

Challenges to this definition:

Sometimes members of separate but similar species mate and succeed in hybrid offspring-

eg.horse+zebra

-produces---zebroids

-both parents belong to

Equidae

family-related but not same species-do not have same # c’somes-why offspring usually infertileSome populations may be able to interbreed,but do not do so because they are in different niches or separated by long distancesHow do we classify organisms that reproduce asexuallyWhat about infertile offspring-Do we exclude humans unable to reproduce from species?What about

in vitro

fertilization

Domesticated dogs-while different breeds-are same species and can interbreedSlide5

Hybrids

To

understand fertile offspring-♀(female) horse + ♂(male) produce_____-mules cannot mate to make more mules-mule is

∴

called

_____________________________________

♂lion and ♀ tiger produce liger hybridChallenges hybrids face cont as a population inc.infertilty

,

Other hybrids:

♀ horse + ♂ donkey=mule

♀ horse + ♂ zebra=

zorse♀ tiger + ♂ lion=liger

mule

Interspecific

hybridSlide6

Populations can become isolated

Grp

from a species separated from rest of species may evolve differently when compared w/rest of population-

eg.mice

have inadvertently crossed oceans on board ships-as they searched for food-may even end up islands away-mice produced on new islands are reproductively isolated-may end up w/ a different frequency of certain alleles-

eg fur colorOther things can produce isolation-such as

mt

. ranges-tree snails in Hawaii-present on only one side of volcano

Also temporal isolation-early migrating birds may have genes isolated from later arrivals

Behavioral isolation-such as different mating calls from same species of birds

Over time-some of these may result in speciation-_________________________________(refer to

ch 10.3)

New species formed from oldSlide7

Autotrophs

and

heterotrophs

Autotrophs-capable

of

________ -

synthesize organics from simple inorganics-usually by photosynthesis Because the food they make is eaten by others __________Examples-cyanobacteria,algae,grass,trees

photosynthesis

producersSlide8

Heterotrophs

—cannot make own food from

inorganics

-but must get from other organisms-from autotrophy and heterotrophy-called ____________________because rely on others, ingest organic matter

-Examples-zooplankton, fish, sheep, insects

consumersSlide9

E.

Consumers

Heterotrophs

-whether

we from

autotrophs

or products of other heterotrophsTake in energy-rich C-compounds, such as sugars,proteins,and

lipids

Only part of human’s diet that we synthesize is Vitamin D -cholesterol molecule in our skin is modified by light into Vitamin DSlide10

Detritivores

Eat non-living organic matter-dead leaves, feces, carcasses-

eg

. Earthworms,woodliceSlide11

Saprotrophs

Live

on or in non-living organic matter, secreting enzymes and absorbing the products of digestion

Fungi, some bacteria-decomposersSlide12

Communities

Group

of populations living and interacting with each other in an area

1 species may interact by feeding on another or being eatenMay provide vital nutrients for another(e.g.-N-fixing bacteria)

One species may provide protection for another-e.g.-aphids protected by ants

One may rely on another for its habitat-e.g.-parasitesSlide13

Ecosystems

______________-

non-living components of environment(

air,water,rocks

)-such measurements include

_______________-

often using electronic probes and data-logging techniquesThese things have a large influence on living things________________-living factors

Random sampling using

quadrats

(to determine the frequency and distribution of a species)-see page 178

Systematic sampling-using a transect=

a line traced from one environment to another-may be a 1,25-50

m long-may set up quadrat every meter along transect

or at specific intervals along transect-counting the organisms that hit each

quadrat

and then counting organisms found in each

quadrat

-no random numbers….see p. 179

abiotic

Temp,pH,light

levels,and

relative humidity

bioticSlide14
Slide15

Where do

autotrophs

get their nutrients?

From inorganic surroundingsPhotosynthetic organisms-

phytoplankton,cyanobacteria,and

plants---photosynthesis

Producers and start of food chainSlide16

Nutrient Cycling

Find

need nutrients w/in own habitat-

C,N,etc

Decomposers

Accessing nutrients through decay

Saprophytes and detritivores break down body parts of dead organismsDigestive enzymes convert organic matter into more usable forms for themselves and other organisms-e.g. proteins from dead organisms are broken down into ammonia(NH3) and then, in turn ammonia has its N converted into nitrates(NO3-) by bacteria.

This recycles nutrients so they are available to other organisms-instead of locked into carcasses or waste products

Decomposers help w/formation of soil

________-rich black layer composed of organic debris and nutrients released by decomposers

Decomposers form humus in compost piles

compostSlide17

The sustainability of ecosystems

Through

recycling of nutrients, ecosystems can contribute to be productive and successful for long periods of time

Convert CO2 to C6H12O6-by producers-used then to make complex

carbs

-like cellulose –or lipids and proteins

Consumers eat producers, and digest the complex organic compounds into simple building blocks---amino acids and sugars,eg,for growth and energyWhen the consumers die,their cells and tissues are broken down by decomposers-minerals ret’d

to soil---for producers ,once again-completing cycle

N-cycle-N important for nucleotides and amino acids—essential to DNA and proteins-essential to existence

Cycle starts w/ N in gas form in atmosphere(N2)—Plants and animals can’t use N2—some bacteria transform it by N-fixing Then absorbed by plant roots(some plants have N-fixing nodules attached to roots)----Plants and animals return N to soil in variety of ways—e.g. ,

ret’d

by decomposition,byurine,fecesSlide18
Slide19

Energy Flow

Importance

of sunlight to ecosystems

Best studied ecosystems on earth’s surface, relying on sunlight-are the focus here

All life relies directly or indirectly on sunSlide20

B. Role of photosynthesis

Take

CO2 and convert to C6H12O6

Light energy converts into chemical energy(food)-rich in energy due to chemical bonds between C and other atoms

Chemical energy measured in calories or kilocalories(kilocalories on

pkg’ing

)Release energy by digesting,also to burnSlide21

Food chain

Process of passing energy from one organism to anotherSlide22
Slide23

Food chain defined as

_______-

arrow shows direction of energy flow

Trophic

level=indicates how many organisms the energy has flowed through

1

st trophic level has autotrophs

or

prodcers;next

level primary consumers; next secondary consumers

Sequence showing feeding relationships band energy flow between speciesSlide24

Cellular respiration and heat

As

grasshoppers consume grass, chemical energy is used for cellular respiration/glucose converted to CO2 and H2O

This takes a

sm

amount of heat in each of grasshoppers cells…heat

lost to environment/thee nutrient and energy passed on to next consumersCells of decomposers also do cellular respiration and thus release heat to environmentSlide25

Heat cannot be recycled

Heat

not actually lost due to law of conservation of energy, but cannot be used again as biological energy sourceSlide26

Where does the heat go?

Heat

lost from ecosystem, radiates into surrounding environment/ecosystem cannot take back heat to use it-not recycled like nutrients

Food chain only adversely affected by the lost heat if sun is lost-thus affecting food chains

Only chemical energy can be used by next

trophic

level and only a small amount of energy absorbed is converted into chemical energyNo organism can use 100% of energy in organic molecules-typically only 10-20% used from previous step…~ 90% lostSlide27

Main reasons not all energy in n organism can be used by all other

trophic

levels:

Not all of an organism is swallowed as a food source-some parts rejected and decay

Not all food swallowed can be absorbed and used in body(e.g.-owl

pellets)

__________________There is considerable heat loss from cellular respiration @ all trophic levels-most animals have to move-requiring more energy than plants-Warm blooded animals use much more

Some organisms die w/o having been eaten by member of next

trophic

levelSlide28

see p.188Slide29

Pyramid of energy

Used

to show how much and how fast energy flows from one

trophic

level to the next in a community

Units=energy per unit area per time=kilojoules per square meter per year(kjm-2yr-1)—take into account rate of energy produced as well qtySlide30
Slide31

Because energy is lost-each level smaller than previous—cannot have higher level wider than

lower levelSlide32

Food webs and energy levels in

trophic

levels

#

of organisms in a chain as well

as qty

sunlight energy available @ start decide length of chainBiomass of a trophic level=estimate of mass of all organisms w/in that level-expressed in mass units, but also take into account area or volume eg.3tons acre-1yr-1

Amount of sunlight reaching fields affects biomass, therefore sunnier region produce more biomass wheat

Some molecules along the way cannot participate in biomass because they re lost-e.g. CO2 lost in cellular respiration, water during transpiration

evapoartion

from

skin,urea lot in excretion-∴not all energy

passed to next trophic level and not all biomass passed onSometimes

foodweb

rather

than

chain is used because there

may

be many feeding relationships going onSlide33
Slide34
Slide35

III.

Carbon cycling

Crucial

element to lifeLife on earth is referred to as C-based

In biosphere as carbs, lipids, nucleic acids and proteins

Also in atmosphere as CO2 and lithosphere ____________________________

i.e.-places where rocks are found

.Slide36

Petroleum-from which gasoline, kerosene, and plastics are made-rich in C having come from decomposed organisms of millions of years ago

Constantly cycled between living organisms and inorganic processes making C available-e.g. C atoms composing the flesh of a giraffe come from the vegetation it ate

When cellular respiration is complete-CO2 released into atmosphere

When organisms die, scavengers eat decomposers break down—which release CO2 back into atmosphere from cellular respirationSlide37
Slide38
Slide39
Slide40

Glucose also starting point for other organics-e.g. lipids and amino acids-which go into cell membranes and proteins-enzymes

Other elements added to glucose-such as NSlide41

C in aquatic ecosystems

CO2

water soluble

Absorbed by bodies of water

Organisms living in water also produce CO2 (by cellular respiration)

____________________________

As CO2 is dissolve in water it forms an acid-decreasing water’s pH

The H+ influences pH

The HCO3 – important inorganic C-based molecule that participates in C-cycleSlide42

Cycling of CO2

Absorbed

by photosynthetic autotrophs such as bacteria, phytoplankton, plants, and trees. They are eaten by consumers, using C in their bodies

Cellular respiration (hereby abbreviated as

cr

) from all trophic levels produce

CO2-releasing

it back into environment

Diffuses into atmosphere or into water Slide43

Methane in C-cycle

Members

of Archaea include methanogens-anaerobic

___________________________

Methanogens also common in wetlands, where they produce marsh gas (may glow)

Also produce CH4 in digestive tract of mammals-

inc. humans-hence the concern w/cattle herds-contribute to greenhouse effect (next section)

When they metabolize food, they produce CH4 (g)-a waste gasSlide44

The oxidation of methaneSlide45

CH4 main ingredient in fossil fuel-__________________

The C found in CH4 borrowed from CO2 molecule removed from atmosphere MYA-during photosynthesis, it then took CH4(g) millions of years to form and accumulate underground

When we burn natural gas, we return C to atmosphere as CO2

What would normally take millions of years to be cycled is thus released rapidly released

Natural gasSlide46

Peat as a fossil fuel

____________=

partially decomposed plant matter

Waterlogged, found in certain wetlands-e.g. Mires and bogs in British Isles,

Scandanavia

, N. Russia, some of E. Europe, N. Canada, N. China, Amazon River basin, Argentina, N. USA9esp.Alaska),

ans some of S.E AsiaDark in color and only certain types of vegetation can grow on its surface-such as Sphagnum mossHeterogeneous but at least 30% of its dry mass must be composed of dead organic material

peatSlide47

Soil that forms peat is called a _______________-typically 10-40 cm thick

Spongy---The high levels of water on peatland force out the air that would normally be between the particles of soil-creates anaerobic conditions—This allows microorganisms to grow but prevents growth of microorganisms that would help in plant matter decomposition

∴

the energy rich molecules that would have been fed upon by decomposers are left behind and transformed, over thousands of years, into energy –rich peat.

histosolSlide48

pH of waterlogged

histosol

-very acidic

not conducive to decomposers

this contributes to the accumulation of non-decomposed material

within the pools of acidic

water- in these wetlands are unique organisms such as some aquatic beetlesto be usable as fuel, cut peat is dried out to reduce humidity. It is then cut into slabs, granules, or blocks and moved where needed

takes a long time to form and considered nonrenewable energySlide49
Slide50

when oil prices are high, peat can be a competitive energy source

many wetlands have been drained to replace w/forests and farmland

concern about wetland preservation has hindered some harvesting of peat…but also because of concern about unique species

also preserve because trapped pollen can reveal info about past climateSlide51

Oil

and gas as fossil fuels

When

left in the correct conditions, partially decomposed peat can be further transformed into coal

Over millions of years, sediments can accumulate above the peat and weight and pressure of those sediments compress it

Under ideal conditions, sedimentation cont. until C-rich deposits are both under huge pressure and exposed to high temperatures (since they have been pushed below Earth’s surface)Slide52

Pressure and heat cause chemical transformations associated w/

lithification

____________________

During lithification

, the molecules are compacted and rearranged

The hydrocarbons-long chains-are of particular interest to industry due to the large amount of energy they hold-ready to be released by burning

Coal must be extracted from below ground to be used for energy-miningFound in seams, where layers of sediments were deposited, covered, and then transformed and other twisted/deformed by geological forces over millions of years

Which is the transformation of sediments into solid rockSlide53

The C-H bonds hold a significant amount of energy, and because there is many-much energy to be released by burning

In addition to coal, the chemical transformations underground can produce other petro products such as crude oil and natural gasSlide54

During the __________________________period MYA, some places in the world that are now dry were underwater-hosted much aquatic or marine life-

inc.

algae and zooplankton

The dry deserts of Saudi Arabia used to be under the Tethys ocean-in the time of Pangea

At that time, under ideal conditions for petro formation, dead remains of organisms in the water did not fully decompose @ the bottom of the ocean-instead forming layers of sediment w/silt

CarboniferousSlide55

In ________-no O2 conditions-the decaying material started to form sludge, as parts of organisms cells decayed and others didn’t-

The lipid component of cells not easily broken down-the accumulated lipid trapped in sediments from a waxy substance called kerogen

Kerogen is also rich in hydrocarbons and also is transformed by pressure and heat as sediments accumulate above it and cause it to rearrange

Natural production of kerogen-long process

Over millions of years and after geological transformation, kerogen in porous sedimentary rock becomes crude oil or natural gas (in g state)-both being less dense than rock, rising through the cracks to the surface

Anoxic conditionsSlide56
Slide57
Slide58
Slide59
Slide60

In order to be used by humans, petroleum products must be trapped and pooled under non-porous rock, preferably one bent by tectonic movement into a dome-as seen above-this allows large

qty’s

of useful gas and oil to collect together in a productive reservoir

Geologists study which parts of the world might contain exploitable gas and oil reserves Slide61
Slide62

CO2 is produced when fossil fuels are used

Substances rich in hydrocarbons can be oxidized using O2 gas from atmosphere when they are burned

Wood, animal dung, can be used-

inc.

for cooking

Fresh, wet dung can be mixed w/other refuse from a farm and put into

lg container, where methane producing microorganisms will decompose and ferment it to produce CH4(g)-Biofuels made in biogas generator take millions of years to formSlide63
Slide64

In efforts to reduce fossil fuel consumption, some countries-e.g. USA and Brazil-have introduced biofuel programs using ethanol made from crops like corn and soybeans

The plant material is fed to microorganisms that ferment it and release ethanol-which is added to gasoline for cars-reduces gasoline use

Standard vehicles cannot use more than 25% ethanol (need 75% or more gasoline)-gasohol

Esp. adapted vehicles can run solely on ethanol

w/a different technique, biodiesel can be made from vegetable oil or animal fat-such as from deep-fat fryersSlide65

Limestone

marine

organisms remove CO2 from water and some is used to make carbonate shells

C can be in form of CO@ dissolved in water or HCO3- ions

Coral polyps build coral reefs-they absorb 2 ions from seawater to build the reef-HCO3-and Ca 2+---forming CaCO3(calcium carbonate)-basis for coral reef-sturdySlide66

Other organisms also use CaCO3 to build shells about their bodies-mollusks-snails, clams, oysters, and mussels—when they die their shells accumulate at bottom of ocean

Microscopic foraminifera are usually on ocean floor and build shells---their shells accumulating in sediment after millions of years through

lithification

—forming limestone

A bldg. material

Carbon sequestration-taking C out of environment and locking-up in a substance for an extended period of time—if natural its bio- sequestration-helps maintain balance in c –cycle

Through biosequestration-accumulation of foraminifera shells as sediment at bottom of ocean can trap C in limestone for millions of yearsMaking of cement by people sues limestone-releases C back to atmosphere as CO2Slide67
Slide68
Slide69
Slide70
Slide71
Slide72

IV. Climate Change

Atmosphere

plays vital role in regulating temperature of earth’s surface

Earth’s surface has an average temp of ~ 14° C/fluctuations only rarely go below -80°C(Antarctica) or higher than 50 ° C (North Africa)

Note-moon ranges -

150°C- +

120°C-same d from the sun-but moon has basically no atmosphereIf the earth had no atmosphere average temp ~ 32° colderSlide73
Slide74

The

roles of CO2 and water vapor in the greenhouse effect

Greenhouse

effect=planet’s ability to use its

atmosphere________________.

to retain heat and keep warm even when no sunlight is hitting the surfaceSlide75

Greenhouse function and design

=walls and roof made of glass, sunlight penetrates through glass, warming up plants inside (sunlight alone is made of short wavelengths-is not warm—rather it’s when sunlight hits an object that some of its energy transforms into heat-known as infrared radiation—which has longer wavelengths)-When sunlight goes through glass, warms up objects inside-radiating their heat to air inside, and some of the heat-not releasing like light –is trapped inside. Glass also plays major role in preventing warm air from rising through convection and dissipating the heat---Result=

________________________________________________

temp inside is warmer than outside-helping plants grow betterSlide76

Greenhouse effect on a planet is caused by atmosphere’s ability to retain heat in a similar to that of greenhouse glass

Greenhouse gases(GHGs)-e.g. Water vapor and CO2 in atmosphere~ to the analogy of the glass

GHGs have ability to absorb and radiate infrared radiation (heat). These gases keep earth’s atmosphere warm by absorbing heat from warmed surface and re-radiating it in all directions-

inc.

back towards

surface

CH4 and N-oxides are also GHGs to a lesser extentSlide77

Climate experts at International Panel on Climate Change(IPCC)-confirmed earth undergoing global warming because of enhanced greenhouse effect (aka-runaway greenhouse effect)

Increasing levels of main GHGs-from human activities, such as burning fossil fuels-causing atmosphere to retain more and more heatSlide78

Different gases, different impacts

2

main factors that determine how much influence a gas will have on the greenhouse effect

1)The

ability of the gas to absorb long-wave radiation(heat)

CH4-eg-has a much greater potential to warm the planet than CO2—however, CH4 has a shorter lifetime in the atmosphere (~12 years—whereas its ~ 50-200 yrs. for CO2)-CH4 can be broken down to other molecules, whereas CO2 is not very reactive, staying in atmosphere much longerSlide79

2)The concentration of that gas in the atmosphere

Studies

of increases in concentrations of

CO2

and CH4 gases over time show that CO2

conc’s

increased ~ 40 %(since 1750) while CH4 have increased more than 150% in the same period-However, CH4 conc’s in Earth’s atmosphere are ~ 1700 ppb while CO2

conc’s

~ 400 ppb-∴ the

conc

of CO2 > 200x more than that of methane

∴ Environmental grps much more worried about CO2

conc’s than CH4 conc’s

-but both do play a role

N-oxides – just over 320 ppb, so they are about the a

5

th

the

conc

of methane-even though they have a global warming potential > 100 x that of CO2, their

conc

in atmosphere is 1000x < than CO2

conc’sSlide80

The warmed earth emits longer wavelength radiation (heat)

When

sunlight enters a greenhouse and touches an object inside, some of the light energy is absorbed and converted into heat energy-i.e. long-wave infrared radiation

On earth,

mts

, forests, rivers, and oceans absorb some of the sunlight and are warmed, most of sunlight bounces off of the surface and

ret’s to space-only sm amt converted into infrared to warm up the surface___________________=albedo

Light-colored

obj’s-eg

ice and wt. sand-have high albedo-∴ little light is absorbed and such

obj’s

don’t heat up as much as dark obj’s (dark rocks and blk sand)

The ability of a surface to reflect lightSlide81

How GHGs heat the atmosphere

w/o

an atmosphere the heat radiating from earth-from low albedo

obj’s would

simply

radiate back into space-and @ night it would be severely cold

However, this doesn’t happen because GHGs absorb and retain infrared coming from surfaceGHGs then re-radiate the heat in all directions (like a radiator in a cold rmSlide82

Some of the heat lost to space, but some of the long-wave

radiation(rad) will

be directed down to surface, keeping it warm/rest radiate w/in atmosphere, -preventing nights that are too cold-whole process staring over w/sunrise in the morning

During the winter, days shorter and < of sunlight less direct, thus earth not warming up as much/in turn, days longer in summer, sunlight hits more directly and intensely---earth’s surface very hot during heat waves and nights are not cool enough to lower daytime temperatures

Fortunately, certain atmospheric gases filter more harmful UV rad-so does not get to such a max temp-like moon

Analogy of atmosphere as blanket-toning down daytime heat and nighttime coldSlide83
Slide84

Global climate change is affected by greenhouse gases

__________=patterns

of temp and

precip,such

as rainfall, occurring over long time periods

Weather can change frequently, but climates not usually changing in our lifetime-rather 1000’s or millions of years

Climatologists and paleoclimatologists collect data about atmospheric conditions in recent decades and distant past (thermometers only been around for a few hundred

yrs

, so temps from so long ago must be inferred by

proxies)_-

see

p.207(NOS)-e.g. using tree rings, coral reef growth, particularly fossils, etc…

ClimateSlide85

Proxy data shows, that in N. hemisphere---15,000 years ago, it was very cold-under a glaciation period-ice age (periods of significant change in climate that produces sheets of ice hundreds of m thick-places where we now have cities-e.g.-Berlin

Last ice age ended about 10,000 years ago-we are now in an interglacial period-warmer temps

Does not take much of a temp drop to produce glaciation-~ 5° C drop from last ice age-we have had a succession of ice ages over millions of yearsSlide86
Slide87

The industrial revolution

Since

such happenings of 1800’s we have increased

qty’s

of CO2 from factories, transport, use of fossil fuels-esp. coal and oil

Burning

forestsEstimates suggest that the level of CO2 in atmosphere has increased by more than 35% compared to pre-industrial revolutionSlide88
Slide89

Recent increases in atmospheric CO2 are largely due to increases in combustion of fossilized organic matter

Conc’s

of major GHGs are naturally low, which prevent much heat retention

#1 source of C emissions from humans is from

_______________

Also from deforestation, heating home w/fossil fuels, high meat diets (this industry highly dependent on fossil fuels)Purchasing goods transported long distances, travel from work to homeOut of -season produce from greenhouses heated by fossil fuelsDiet contributes to CH4 (cattle

industry)

Oxides of N produced burning fossil fuels

,using

organic and commercial fertilizers, industrial processes

from transportation-cars, trucks, trains, airplanesSlide90

Threats to Coral reefs

Organisms

sensitive to water temp, acidity, depth of water-all factors which are changing

Increased CO2 in air means an increase in ocean as well, lowering pH-death of coral polyps and algae—reefs-once dead-will not be rebuilt

Color changes to bone white

Coral reef death eliminates the home for many organismsSlide91
Slide92

Are humans causing climate change?

“climate-change deniers” have a # of criticisms about IPCC’s findingsSlide93
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