Topic 5 – Ecology & Evolution

5.1 Communities and Ecosystems

Define:

Ecology—the study of relationships between living organisms and between organisms and their environment.

Ecosystem—a community and its abiotic environment.

Population—a group of organisms of the same species who live in the same area at the same time.

Community—a group of populations living and interacting with each other in an area.

Species—a group of organisms which can interbreed and produce fertile offspring.

Habitat—the environment in which a species normally lives or the location of a living organism.

5.1 Communities and Ecosystems

5.1.2

autotroph (producer) – organisms that use an external energy source to produce organic matter from inorganic raw materials

Examples: trees, plants, algae, blue-green bacteria

5.1 Communities and Ecosystems

heterotroph (consumer) – organisms that use the energy in organic matter, obtained from other organisms

Three Types:

1. consumers

2. detritivores

3. saprotrophs

5.1 Communities and Ecosystems

1. Consumers – feed on other living things

2. Detritivores – feed on dead organic matter by ingesting it

3. Saprotrophs (decomposers) – feed on dead organic material by secreting digestive enzymes into it and absorbing the products

5.1 Communities and Ecosystems

5.1.4

Describe what is meant by a food chain giving three examples, each with at least three linkages (four organisms).

A food chain is a sequence of relationships between trophic levels where each member feeds on the previous one.

5.1 Communities and Ecosystems

5.1.5

Describe what is meant by a food web.

A food web is a a diagram that shows the feeding relationships in a community. The arrows indicate the direction of energy flow.

5.1 Communities and Ecosystems

5.1.6Define trophic level. A trophic level is where an organism is

positioned on a food web.ProducerPrimary consumerSecondary consumerTertiary consumer

5.1 Communities and Ecosystems

5.1.7

Deduce the trophic level of organisms in a food chain and a food web. (3)

• The student should be able to place an organism at the level of producer, primary consumer, secondary consumer etc, as the terms herbivore and carnivore are not always applicable.

5.1 Communities and Ecosystems

5.1.8

Construct a food web containing up to 10 organisms, using appropriate information.

5.1 Communities and Ecosystems

5.1.9

State that light is the initial energy source for almost all communities.

• xref- Photosynthesis

5.1 Communities and Ecosystems

5.1.10

Explain the energy flow in a food chain.

• Energy losses between trophic levels include material not consumed or material not assimilated, and heat loss through cell respiration.

5.1 Communities and Ecosystems

5.1.11

State that when energy transformations take place, the process is never 100% efficient

5.1 Communities and Ecosystems

5.1.12

Explain reasons for the shape of pyramids of energy.

• A pyramid of energy shows the flow of energy from one trophic level to the next in a community. The units of pyramids of energy are therefore energy per unit area per unit time, e.g. KJ m-2 yr-1

5.1 Communities and Ecosystems

5.1 Communities and Ecosystems

5.1 Communities and Ecosystems

5.1.13

Explain that energy enters and leaves ecosystems, but nutrients must be recycled.

Energy enters as light and usually leaves as heat.

Nutrients do not usually enter an ecosystem and must be used again and again (nutrient cycles). Nutrients can be substances such as Carbon dioxide, Nitrogen, and Phosphorus

Key processes in the Carbon cycle

• Combustion

• Cell respiration

• Photosynthesis

• Fossilisation

• Interaction between living organisms

The layers of the

atmosphereThe troposphere is the part of the atmosphere in the biosphere

The stratosphere contains the ozone layer

The stratosphere is also a zone of warm air that keeps a lid on the troposphere. It does not mix with the upper atmosphere

© Windows to the Universe© Text 2007 Paul Billiet ODWS

The Greenhouse Effect

• Earth has a natural greenhouse effect

• This is important to prevent large fluctuations in temperature

• Without a greenhouse effect on Earth, we would not have life as we know it.

Greenhouse Effect

Light from the sun has short wavelengths and can pass through most of the atmosphere.

This sunlight warms the Earth which in turn emits long wave radiation.

This long wave radiation is bounced back by the greenhouse gases, such as carbon dioxide, methane, CFCs, water vapour, and sulphur dioxide

The Greenhouse Effect

• The molecules of some gases in the atmosphere absorb heat energy and retain it

• This can be a good thing

• Without an atmosphere the Earth would have same temperature as the moon

• Moon mean surface temperature -46°C

• Moon temperature range: -233 to +123°C

© 2007 Paul Billiet ODWS

The Greenhouse Gases

• H2O vapour

• CO2

• CH4

• NOx

• CFC

© Oceanworld 2005 Robert R Stewart

© Text 2007 Paul Billiet ODWS

The Greenhouse Gases• Water vapour in the atmosphere is stable

• The atmosphere is saturated

• CO2 levels are currently rising

• They have varied in the past

• Methane levels are increasing:as more cattle are farmed, as more paddy fields are planted, as permafrost melts

• NOx levels increase due to increased circulation of motor vehicles

© 2007 Paul Billiet ODWS

Mauna Loa Observatory

© Mauna Loa Observatory Site

© Earth System Research Laboratory

© Earth System Research Laboratory

Carbon dioxide a greenhouse gas

© Mauna Loa Observatory Site

South Pole Data

Samoa data

© Australian Antarctic Division

© New Scientist : Environment

Levels during the last ice age

© Dennis Hartmann: Universoty of Washington: Department of Atmospheric Sciences

Out of the ice age

Since the Industrial Revolution

Concentration of Carbon Dioxide from trapped air measurements for the DE08 ice core near the summit of Law Dome, Antarctica. (Data measured by CSIRO Division of Atmospheric Research from ice cores supplied by Australian Antarctic Division)

Is it really getting warmer

1979 2003

© NASA

5.2 The ENHANCED greenhouse effect

Phenomenon

The mean global temperature has risen about 1 degree Celsius since 1856. We saw an increase between 1910 and 1940, and from 1970 onwards.

5.2 Enhancing the greenhouse Effect

Human Activities• Increased burning of fossil fuels releasing greenhouse

gases (CO2, oxides of Nitrogen)

• Deforestation – less trees to convert CO2 back to O2

• Raising cattle and paddy fields release methane• CFCs were used as a propellant in aerosols and as a

coolant in refrigerators, freezers and air conditioning units. Old cooling machinery can still leak CFCs and need to be disposed of carefully – CFCs are persistent

• Other industrial activities that release other greenhouse gases

The Precautionary Principle

• The precautionary principle holds that, if the effects of a human-induced change would be very large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding.

• This is the reverse of the normal situation where those who are concerned about the change would have to prove that it will do harm in order to prevent such changes going ahead.

Evaluate the precautionary principle…

• …..as a justification for strong action in response to the threats posed by the enhanced greenhouse effect

• Economic harm Vs harm to environment for future generations

• Should the health and wealth of future generations be jeapardised?

• Is it right to knowingly damage the habitat of species other than humans? Cause extinction?

• Need for international cooperation• Inequality between those contributing most to the harm,

and those who will be most harmed

The consequences• Sea level rise

Changing sea ice... • Flooding coastal areas

Reduced agricultural landDisplacement of populations

• Climate change and changing weather patterns

• Displacement of ecosystemsChange in range of insect vectors of pathogensReduced biodiversity

© 2007 Paul Billiet ODWS

The consequences

• Increased rates of photosynthesis

• Increased agricultural production at high latitudes

• BUT faster growth means: less protein in cerealstrees taller and more exposed to storm damage

© 2007 Paul Billiet ODWS

Knock-on effects• Increased temperature melts the permafrost• Frozen plant remains decompose• More methane released• Similarly soils will lose organic carbon (humus)

more rapidly in a warmer climate• Ice caps melt more sea exposed• Snow reflects light (high albedo)• Water absorbs light, increases warming• More CO2 dissolving in water lowers pH• Currently this is buffered and remains stable• Eventually pH will drop sea life will die CO2

produced as organisms decompose© 2007 Paul Billiet ODWS

What can be done?Reduce carbon emissions• Improve mass transport systems (public transport)• Design more efficient motors• Design alternative power sources• Hydrogen powered motors

BUT problems of fuel reservoir, delivery, fabrication

• Renewable energy (wind, tidal, hydro, geothermal, biomass)BUT growing crops for biofuel reduces farmland available for foodHydroelectric dams disrupt river ecosystems

• Nuclear powerBUT problems of nuclear waste treatment/storage© 2007 Paul Billiet ODWS

What can be done?

Increase natural CO2 sequestering

• Reduce deforestation

• Increase reforestation

© 2007 Paul Billiet ODWS

What can be done?

Artificial CO2 sequestering

• Filter CO2 sources using hydroxide scrubbers

• Injection of CO2 into deep ocean layersForms CO2 reservoirsImpact on sea life unknown

• Injecting CO2 into disused oil wells

• Mineral deposition as carbonates© 2007 Paul Billiet ODWS

The bottom lineTwo factors will ultimately govern what happens:1. Human population growth

More people means greater demand for non-renewable resources

2. The ecological footprint of each individual humanHigher standards of living usually means higher consumption of fossil fuels

The planet will look after itself in the endThere are plenty of examples where human

communities have disappeared because they outstripped the environmental resources

© 2007 Paul Billiet ODWS

The planet will look after itself in the end

• Easter Island (Rapanui) in the Pacific

• Settled between AD900 and 1200

• Community in severe decline AD 1700

• Cause: excessive deforestation

© Text 2007 Paul Billiet ODWS

The Moai statues, Easter Island © Martin Gray, World Mysteries

The planet will look after itself in the end

• Chaco Canyon, New Mexico

• Anasazi culture • AD 850 – 1250• Cause: Deforestation

combined with a decline in rainfall

© New Mexico Tourism Department

© Text 2007 Paul Billiet ODWS

The planet will look after itself in the end

• Mesopotamia• Sumerian civilization• 3100 – 1200 BC • Increased salt levels

in soil due to irrigation systems & arid environment

• Reduced food yield

© Text 2007 Paul Billiet ODWS

© Asociación Cultural Nueva Acrópolis en Barcelona

The planet will look after itself in the end

• Greenland• Viking colony• AD982 – 1350• Cause: Deforestation,

soil degradation & cooling of the climate

© Emporia State University

© Text 2007 Paul Billiet ODWS

forumpolitics.com/pics/earth-photo.jpg

Who’s next?

© NASA

5.3 Populations

5.3.1

Outline how population size is affected by natality, immigration, mortality and emigration.

5.3 Populations

• Natality – offspring are produced and added to the population

• Mortality – individuals die and are lost from the population

• Immigration – individuals move into the area from somewhere else and add to the population

• Emigration – individuals move out of the area and are lost from the population

5.3 Populations

5.3.2

Draw a graph showing the sigmoid (S-shaped) population growth curve.

5.3 Populations

5.3.3

Explain reasons for the exponential growth phase, the plateau phase and the transitional phase between these two phases.

5.3 Populations

Exponential Phase

Population increases exponentially because the natality rate is higher than the mortality rate. This is because there is an abundance of food, and disease and predators are rare.

5.3 Populations

Transitional Phase

Difference between natality and mortality rates are not as great, but natality is still higher so population continues to grow, but at a slower rate.

Food is no longer as abundant due to the increase in the population size. May also be increase predation and disease.

5.3 PopulationsPlateau PhaseNatality and mortality are equal so the population

size stays constant.

Limiting Factors:• shortage of food or other resources• increase in predators• more diseases or parasites

If a population is limited, then it has reached its carrying capacity

5.3 Populations

Carrying capacity

The maximum population size that can be supported by the environment

5.3 Populations

5.3.4List three factors which set limits to

population increase.

Limiting Factors:1. shortage of food or other resources2. Increase in predators3. More diseases or parasites

5.4 Evolution

5.4.1Define Evolution—the process of cumulative

change in the heritable characteristics of a population.

Macroevolution – the change from one species to another. i.e. – reptiles to birds

Microevolution – the change from one variation within a species to another. i.e. – a Chihuahua and a Great Dane

5.4 Evolution

Evidence for evolution….

• Fossil record

• Selective breeding of domesticated animals

• Homologous structures

The Fossil Record• Darwin first collected convincing evidence for biological evolution

• Earlier scholars had recognised that organisms on Earth had changed systematically over long periods of time.

• Because bottom layers of rock logically were laid down earlier and thus are older than top layers, the sequence of fossils also could be given a chronology from oldest to youngest.

• Today, many thousands of ancient rock deposits have been identified that show corresponding successions of fossil organisms.

• Hundreds of thousands of fossil organisms, found in well-dated rock sequences, represent successions of forms through time and manifest many evolutionary transitions.

Life Form Millions of Years Since First Known Appearance

• Microbial (procaryotic cells) 3,500• Complex (eucaryotic cells) 2,000• First multicellular animals 670• Shell-bearing animals 540• Vertebrates (simple fishes) 490• Amphibians 350• Reptiles 310• Mammals 200• Nonhuman primates 60• Earliest apes 25• Ancestors of humans 4• Modern humans 150,000 years

Archaeopteryx

Selective breeding

Homologous structures• Inferences about common descent are reinforced by

comparative anatomy. For example, the skeletons of humans, mice, and bats are strikingly similar, despite the different ways of life of these animals and the diversity of environments in which they flourish.

• The correspondence of these animals, bone by bone, can be observed in every part of the body, including the limbs; yet a person writes, a mouse runs, and a bat flies with structures built of bones that are different in detail but similar in general structure and relation to each other.

• Scientists call such structures homologous structures and have concluded that they are best explained by common descent.

The pentadactyl limb

5.4 Evolution

5.4.3

Populations tend to produce more offspring than the environment can support.

5.4 Evolution

5.4.4• The consequence of the potential

overproduction of offspring is a struggle for survival.

• More offspring are produced than can be supported, therefore there is a struggle to survive, where some live and some die.

5.4 Evolution

5.4.5

Members of a species show variation.

5.4 Evolution

5.4

Explain how sexual reproduction promotes variation in a species.

• Independent assortment

• Crossing over

• Random fertilisation

• Mate selection

Natural selection – the mechanism of evolution

• Since organism’s traits vary, some organisms are more adapted to survival than others.

• When there is a struggle to survive those with favorable traits tend to survive long enough to pass them on.

• Those that have less favorable traits die before being able to pass the traits on.

5.4 Evolution

5.4.7

Explain how natural selection leads to evolution

• The Darwin–Wallace theory is accepted by most as the origin of ideas about evolution by means of natural selection

• 1854 - Wallace left Britain on a collecting expedition to the Malay Archipelago (now Malaysia and Indonesia). He spent nearly eight years in the region collecting almost 110,000 insects, 7500 shells, 8050 bird skins, and 410 mammal and reptile specimens, including over a thousand species new to science; some of his specimens can be seen in the Sarawak museum.

• His best known discoveries are probably Wallace's Golden Birdwing Butterfly Ornithoptera croesus

• The book he wrote describing his work and experiences, The Malay Archipelago, is the most celebrated of all travel writings on this region, and ranks with a few other works as one of the best scientific travel books of the nineteenth century.

• In February 1855, whilst staying in Sarawak, Wallace wrote what was to become one of the most important papers on evolution.

• Wallace's "Sarawak Law" paper made a big impression on the famous geologist Charles Lyell.

• Soon after Darwin had explained his theory of natural selection to Lyell (during a visit he made to Down House in April 1856) Lyell sent a letter to Darwin urging him to publish the theory lest someone beat him to it.

• Darwin began to write On the Origin of Species.

• 1858 - the idea of natural selection as the mechanism of evolutionary change occurred to Wallace .

• He wrote out his ideas in full and sent them off to Charles Darwin, who he thought might be interested.

• Unknown to Wallace, Darwin had in fact discovered natural selection about 20 years earlier, and was part way through writing his "big book" on the subject.

• Darwin was therefore horrified when he received Wallace's letter, and appealed to his influential friends Charles Lyell and Joseph Hooker for advice on what to do.

• Lyell and Hooker presented Wallace's essay, along with two excerpts from Darwin's writings on the subject, to a meeting of the Linnean Society of London in July 1858.

• These documents were published together in the Society's journal on 20 August of the same year as the paper

5.4 Evolution

5.4.8

Explain two examples of evolution in response to environmental change; one must be multiple antibiotic resistance in bacteria…..

Evolution in bacteria

and the peppered moth (Biston betularia) is another good example!.....

Example 1:’Peppered Moth’

Example 2:Resistance to antibiotics in bacteria.

• If a culture of bacteria (eg.within a sick patient) is treated with antibiotics, Most of the bacteria are killed. A small number that naturally have genes resistant to antibiotics will survive.

• It is important to note that these bacteria did not "learn" to resist antibiotics. These bacteria have mutated genes that somehow allowed them to resist antibiotics.

• These surviving bacteria will reproduce and pass on their resistant genes. Natural Selection “chose” the antibiotic resistant ones because the rest of bacterial population is killed by the antibiotic.

• These surviving Mutant bacteria can become a problem when trying to kill a bacterial infection in a patient, because if the bacterium is resistant to the antibiotics given, then it can't be killed.

• Someone has to come up with a new antibiotic that it is not resistant to, which can be a difficult expensive process

5.5 Classification

5.5.1

Outline the binomial system of nomenclature (also referred to as a scientific name)

Swedish botanist, Carolus Linnaeus (1707-1778)

Internationally recognised name for each species

5.5 Classification

Rules for binomial nomenclature:1. The first name is the Genus name2. The Genus name is CAPITALISED3. The second name is the species name4. The species name is not capitalised5. Italics are used if the name is printed6. The name is underlined if handwritten Homo sapiens, Panthera leo, etc.

5.5 Classification

5.5.2

List the seven levels in the hierarchy of taxa - use an example from two different kingdoms for each level.

Kingdom

Phylum

Class

Order

Family

Genus

Species

Animalia

Chordata

Mammalia

Cetacea

Balaenopteridae

Balaenoptera

musculus

Plantae

Coniferophyta

Pinopsida

Pinales

Taxodiaceae

Sequoia

sempervirens

Kings Play Chess On Folding Glass Stools

Blue Whale Coast Redwood

King Phillip Came Over For Good Soup Kissing P

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Gross S

ometim

es

or make your o

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Bryophyta – mosses and liverworts (0.5m)

• No roots, just rhizoids

• Small

• Spores produced in capsules Mosses have

simple leaves and stems

Liverworts have

a flattened “thallus”

Filicinophyta – ferns (<15m)• Roots, leaves and short (non-woody)stems• Pinnate leaves

• Curled up in buds

• Spores in sporangia (underside of leaves)

shallow roots

Coniferophyta – conifers (100m)

• Shrubs or trees with roots, leaves and woody stems

• Produce seeds in female cones(Male cones pollen)

Angiospermatophyta – flowering plants (100m)

• Roots, stems and leaves

• If shrubs or trees, woody stems

• Produce seeds inside ovaries.

Fruits develop from ovaries, to

disperse seeds

Porifera (sponges)

• Poriferans don't have mouths; instead, they have tiny pores in their outer walls through which water is drawn.

Cnidaria (corals, anemones and jellyfish)

• Single opening to stomach, that functions as both mouth and anus

• It has radial symmetry• Armed with stinging cells called nematocysts.

Platyhelminths (flatworms)

• Bilaterally symmetrical

• Triploblastic (composed of three fundamental cell layers)

• no body cavity other than the gut and lack an anus

Annelida (segmented worms)

• Segmented, long body

• Mouth and anus

Mollusca

• The body has a head, a foot and a visceral mass, covered with a mantle that typically secretes the shell.

• The buccal cavity, at the anterior of the mollusc, contains a radula — a ribbon of teeth

• The ventral foot is used in locomotion.

• Molluscs are coelomate.

Arthropoda• Exoskeleton made of chitin (may be

strengthened with calcium carbonate)

• Jointed limbs

Design a dichotomous key for 8 organisms