Effects of the Environment on Organisms
PRELIM Biology notes 1428750942975Module 2 : Cell Structure Inside a cell Cells are the simplest of life, anything smaller than a cell is not alive.Cells are made up of organelles Organelles carry out specific processes to keep the cell functioning and healthy Several organelles are surrounded by a membrane, which acts a barrier to control the movement of substances in and out. THE CELL THEORY SUGGESTS THAT ALL THINGS ARE MADE OF CELLS THE CELL IS THE SMALLEST UNIT OF LIFEALL NEW CELLS COME FROM PRE-EXISTING CELLS Types of cells All cells can be classified as prokaryotic or eukaryotic.PROKARYOTIC CELLS : Are more simple, and do not have membrane bound organellesNo nucleus Bacteria Only unicellular EUKARYOTIC CELLS: Are more complex and contain an array of membrane bound organellesMembrane bound nucleus Paired chromosomes Could be single celled or multi celled Bacteria Exists only as unicellular organism and reproduce by asexual reproductionSome photosynthesis or chemosynthesis; others absorb it from outside of cellHave cell wallIncludes bacteria and cyanobacteria e.g E. coli, staphylococcus Archaea Only exists as unicellular and reproduce by asexual reproductionAbsorbs food from outside of cell Prokaryotic and have cell wallIncludes thermophiles (organisms which can survive at extreme low or high temperatures) Protista Exists mostly as unicellular organisms (occasionally as multicellular) and reproduce sexually or asexually.Some absorb or ingest food. Others produces Eukaryotic and contain a cell wallIncludes algae and protozoa Protists are Eukaryotic organisms which are not only animal but also plant or fungal cells. Protists use a range of cell structures including:Cilia: many / a collection of small protrusions which cover the surface of the cell. Cilia generally move back and forth in unison to push the cell alongFlagella: one or two large, long protrusions on the surface of the cell. Flagella can either move back and forth in a smooth wavelike motion or a propellor-like motion. FungiExists mostly as multicellular organisms and reproduce sexually or or asexuallyAbsorb food from their surroundingThey are eukaryotic and contain cell wall Plant Exists as multicellular organism and reproduce sexually or asexuallyProduce food by photosynthesis Eukaryotic and contain cell wallE.g flowering plants and fernsAnimal Exists as multicellular organisms and reproduce sexually Ingests food for nutrition Eukaryotic, no cell wall Functions of animal / plant cell organelles Organelle functioneukaryotic/ prokaryotic Cell membraneTo protect cell from surroundings. The Cell membrane controls the movement of substances in and out of the cells and organelles. It is selectively permeable to ions.Eukaryotic plant and animal Endoplasmic reticulum (rough and smooth)The ER serves many functions including folding of proteins molecules in sacs called cisternae and transporting protein.Eukaryotic, animal cellsmitochondriaMain function is to perform cellular respiration to produce ATP and to regulate cellular metabolism. The mitochondria acts like a digestive system which takes in nutrients, breaks them down and creates energy rich molecules for the cell.Eukaryotic plant and animal vacuoleEnclosed compartments that are filled with both inorganic and organic molecules (water, salts proteins and carbohydrates, along with water) to support organelles . Holds waste for removal Eukaryotic plant and animal Cytoplasm The cytoplasms function is to support cellular molecules and cell organelles which it also helps suspend. the cytoplasm also is part of protein synthesis, glycolysis ( first stage of cellular respiration, mitosis, meiosis. The cytoplasm also helps move hormones and other materials around as well as dissolving waste within the cellEukaryotic and Prokaryotic ribosomeAppear as small dense rounded granules in electron micrographs of cells They are made of chemicals RNA and protein, and carry out the genetically coded instruction of DNA to produce more protein. Amino acids are joined to form polypeptides the structural units of proteins.Eukaryotic and Prokaryotic Chloroplasts Allows plants to go through photosynthesis. Pigments for this process embedded in membrane. Eukaryotic plant cellsCell wallThe main roles of the cell wall include, providing rigidity, tensile strength, structural support, protection against mechanical stress and infection as well as aiding the diffusion of gases in and out of the cell.Prevents water lossHelps in osmotic regulationEnables transport of substance and information from the interior of the cell to its exterior and vice versa Eukaryotic plant cellsGolgi apparatus Processes and and packs and sorts cell products . they are involved in adding proteins and carbohydrates to cell products and they also provide a membrane around the cell to package themProkaryotic cells Nucleus The nucleus is where all all the cell's hereditary information is stored. It also responsible for controlling the growth and reproduction of the cell. The nucleus and the cytoplasm needs to communicate and this is enabled by the pores in the double nuclear membrane which surrounds the nucleus, and regulates the passage of substances in and out of the nucleus.Eukaryotic plant and animal Lysosomes Lysosomes are formed by the Golgi body. They contain digestive enzymes that are responsible for splitting complex chemical compounds into simpler ones e.g proteins broken down into amino acidThe lysosome may destroy an entire cell this process is known as apoptosis.Eukaryotic plant and animal Centrioles Eukaryotic Animal cells The structure of membranes in cells : the fluid mosaic modelThe cell membrane controls the exchange of material between the internal and external environments of the cell. It is selectively permeable, meaning that it allows only certain molecules or ions into or out of the cell. The structure of the cell membrane allows the concentration of substances inside to remain fairly constant and different from the external environment.The fluid mosaic model describes the cell membrane as a double layer of lipids ( a lipid bilayer) with the ability to flow and change shape, like a two dimensional fluid. Specialised protein molecules are embedded in the lipid in various patterns like a mosaic. Both proteins and phospholipids help to control the exchange of materials between the external and the internal environments.The lipid component & membrane proteins The fluid part of the cell is composed of two layers of phospholipids forming a phospholipid bilayer. Each phospholipid in these layers can be presented by a head and two tails. The head is made of a phosphate group which makes it hydrophilic ( able to absorb or dissolve in water). The fatty acid tails are hydrophilic ( unable to absorb or dissolve in water ). The hydrophilic heads are positioned facing outward and the hydrophobic tails are facing inwards .It is NOT a rigid layer and hence the term Fluid. A type of lipid called cholesterol is interspersed among the phospholipid layers in animals, making the membrane more flexible, in plants the flexibility is changed by the presence of phytosterol. Cell membranes are able to break and reassemble themselves during processes such as mitosis or meiosis.Some proteins penetrate all the way through the bilayer forming channels which allow some materials to pass through such as aquaporin which helps transport water molecules.These proteins allow cell to cell interaction and communication and exchange of substances between the cell and the external environment.Adhesion proteins link together and help maintain the organisms three dimensional structure.Transport proteins act like passageways that allow specific substances to move across the membraneReceptor proteins are different in different types of cells, they cause the cell to respond to only specific signals from substances such as hormones that bind to them giving them specific functionsGlycoproteins are made of a protein molecule with a carbohydrate attached to it. These proteins identify the the cell and are also called antigens or marker cells. They allow the immune system to distinguish between foreign particles and body’s own cells. This ensures that the immune system only destroy foreign particles.Technologies used to determine cell structureResolution is the ability to distinguish between two seperate objects, in order to see the details of the object.It is measured in nanometers.Light microscopes : in compound light microscopes, a light source passes through a condenser then through the specimen. This beam of light then passes through the convex objective lenses, where the image is magnified and viewed through the ocular lens. They can magnify images up to 1500 x depending on the lenses used. The maximum resolution is 200 nm. Both living and and non-living specimen can be viewed using a compound light microscope Fluorescence microscopes: The fluorescent microscope work very similarly to the compound light microscopes. Extra features enable scientists to produce images of specific parts of cells. The sample is labelled with a fluorescent substance that will attach to the structures that the scientists want to specifically observe. The sample is illuminated with a high intensity source of light that causes the fluorescent substance to emit light, this light is directed through filters that separate it from surrounding light and only the specified part is seen through the ocular lense.Electron Microscopes: There are two types of electron microscopes: the scanning electron microscope (SEM) and the transmission electron microscope (TEM). A TEM produces an image by passing a high voltage electron beam through a very thin specimen that is semi transparent to electrons. A SEM detects secondary electrons that arise from the surface as a result of excitation by the original electron beam.Cell Scan Software: Produces three dimensional representations of cell structures allowing a much greater understanding of cell structure and function.Confocal laser scanning microscopy: used to highlight the three-dimensional structure of samples being studied. A laser produces a narrow intense beam of light that is focused to a pinpoint on the sample while all the surrounding, out of focus areas are not included in the image. This used to study structural components of the cells.Chapter 3: Cell FunctionMovement of molecules across cell membranes The permeability of a cell membrane to a molecule depends on the Size: small molecules can move across membranes more quickly than large moleculesElectrical charge: molecules with electrical charges cuh as sodium and potassium are not very soluble and therefore have low membrane permeability. Neutral molecules such as oxygen and carbon dioxide are soluble in lipids and have a high permeability.Water is a polar molecule and and is not lipid-soluble, however it moves through the membrane through pores called aquaporin by a process called osmosis.Molecules that have low permeability rely on carrier proteins to transport them across membranes in cells Diffusion The transport of materials into and out of the cell can be either passive or active transport. Passive movement requires no energy input and includes the process of diffusion and osmosis. Diffusion is the net movement of any molecules from a region of high concentration to a region of low concentration of that substance until equilibrium is reached.Movement from an area of high concentration to an area of low concentration is described as movement along a concentration gradient.The rate of diffusion is dependent on the concentration gradient.Diffusion can also speed up or slow down depending on the temperature: heat increases the rate of diffusion because there is more kinetic energy within the particles.Simple diffusion across a cell membrane: small uncharged particles such as oxygen move easily through the cell membrane through simple diffusion. These particles move easily through the phospholipid molecules from a region of high concentration to an area of low concentration, where the concentration gradient remains low because oxygen is continuously used in cellular respiration. This means that oxygen is promoted from the outside of the cell where it is high in concentration.Facilitated Diffusion is occurs when large molecules such as glucose and amino acids as well as charged particles like sodium ions do not easily pass through the phospholipid bilayer. This where the carrier proteins and channel proteins are used to the assist the particles in diffusing into the the cell.Osmosis Osmosis is a type of diffusion. It is the net movement of solvent molecules from a region of high solvent concentration to a region lower solvent concentration through a semipermeable membrane. Water moves through Aquaporin the channelHypertonic: Solution with higher concentration of water than cell. This iActive transport The movement of molecules from a low concentration to a high concentration through selectively permeable membrane.From an area of low solute concentration to an area of high solute concentrationMoves against the concentration gradient.Energy is requiredModule 3 Summary - Biological Diversity Effects of the Environment on Organisms Inquiry Question 1: How do environmental pressures promote a change in species diversity and abundance?Predict the effects of selection pressures in ecosystems, including:Biotic factors - living (fungi, plants)Abiotic factors- non living ( wind)Biotic FactorsBiotic selection pressures that affect ecosystems:- Availability of food → low food availability = decreases in population + abundance - Mates → able to find mate = reproduction + increase in population + abundance - Predators → high amount of predators = decrease in prey population + abundance - Competitors → high amount of competitors = competition for resources + decrease in population If biotic selection pressures are positive → population abundance and diversity increase. If selection pressures are negative → population abundance and diversity decrease.Abiotic factorsAbiotic selection pressures that affect ecosystems:- temperature - oxygen availability → low oxygen = low respiration + decrease in organisms that can inhabit the environment - water availability → low water = competition for water + decrease in abundance species If abiotic selection pressures are positive → increase in abundance and diversity. If abiotic selection pressures are negative → decrease in abundance and diversity Investigate changes in a population of organisms due to selection pressures over time, for example:Cane toads in AustraliaPrickly pear distribution in Australia Cane toads in Australia Introduced as biological control for cane beetle. No natural predators → +ve selection pressure, population increased. Increased food source of native fauna → +ve selection pressure. Toads became fast moving and directional due to spatial sorting → +ve selection pressure. Larger size and longer legs → +ve selection pressure. Development of arthritis in older, larger toads → -ve selection pressure. Overall population increase due to +ve selection pressures.Prickly pear distribution in Australia The prickly pear was introduced to use the insects that feed on it. It was moved around Australia by people as food source for livestock. Good in arid climates → positive selection pressure, ↑ in population. Methods for removal were not effective + population ↑ rapidly. Cactoblastis moth introduced as biological control. Placed moths on the pear → larvae eat through cactus pad → plant dies. After 7yrs population was removed. +ve selection pressure → Aust. climate-ve selection pressure → mothAdaptations Inquiry Question 2: How do adaptations increase the organism’s ability to survive?Organisms have different characteristics that enable them to survive and reproduce in different environments. This is known as adaptation. Adaptations enable plants/animals to: live in extreme environments, access resources & mates and defend themselvesConduct practical investigations, individually or in teams, or use secondary sources to examine the adaptations of organisms that increase their ability to survive in their environment, including:Structural adaptationsare anatomical features that improve an organism’s ability to cope with abiotic and biotic factors in their enviro. Appropriate adaptations increase the chance of survival and reproduction. Body shape and size are structural adaptations. Example: thick fur to survive the coldPhysiological adaptationsinternal features of an organisms that enable them to survive in their enviro. Example: camouflaging.Behavioural adaptations are actions that an organism takes to improve survival and reproduction. Example: seeking or leaving shade/ shelter.Investigate, through secondary sources, the observations and collection of data that were obtained by Charles Darwin to support the Theory of Evolution by Natural Selection, for example:Charles was an English naturalist who sailed on HMS BEGAN. He collected specimens from every location the ship visited. In 1858 Charles proposed a process by which evolution occurs called “natural selection”Finches of the Galapagos Islands he visited the Galapagos island in 1835. During his visit he realised finches were similar on diff islands and showed distinct variation in beak size and structure. He realised beaks were depending on local food source. From this Darwin conducted that finches arrived there in the past had changed overtime to better suit their environments.Australian flora and faunaTheory of Evolution by Natural Selection Inquiry Question 3: What is the relationship between evolution and biodiversity?Explain biological diversity in terms of the Theory of Evolution by Natural Selection by examining the changes in and diversification of life since it first appeared on the Earth As a result of the high temperatures at the centre of the Earth and due to volcanic activity, there as an emission of gases, or out-gassing, of volatile molecules, such as water (H2O), methane (CH4), ammonia (NH3), hydrogen (H2), nitrogen (N2), andcarbon dioxide (CO2). The environment was also anoxic as there was no free oxygen, This meant that there was no ozone layer. The energy for driving these reactions could have come from a number of sources, in particular the sun. Ultraviolet light would easily have reached the Earth’s surface because no ozone layer existed. Other possible energy sources could have been lightning, hot springs and volcanoes.- Panspermia theory – This theory suggests that life could have arisen once, or several times, at various times and in various parts of the universe.Biochemical Evolution Theory – This theory suggests that certain conditions of Early Earth generated the organic compounds and the right environment for the first production of a living organism. Evidence to support this theory is; Oparin suggested that organic compounds could have formed in the early Earth’s oceans from more simple compounds, where the energy source was the excessive UV radiation of the sun.The Urey-miller experiment is to investigate that chemical evolution occurred and led to origin of life. The work of Urey and Miller has shown that the major building blocks for living organisms could have formed on Early Earth with its primitive atmosphere and energy sources of lightning and UV radiation. This is called chemical evolution.An anoxic atmosphere is one defined as being deficient or lacking in oxygen. anaerobicAn oxic atmosphere is one where oxygen is readily available. Aerobic change from an anoxic atmosphere free of oxygen to an oxic atmosphere with plenty of available oxygen had a significant influence on the conditions of Early Earth and hence the evolution of living things. This major change to the atmosphere and increase in oxygen inhibited the growth of anaerobic organisms and caused them to decline, while photosynthetic organisms became more abundant. As the oxygen began to collect in the atmosphere, it reacted with the sun’s UV radiation to produce ozone (O3). As the amount of oxygen increased, so did the amount of ozone produce.Analyse how an accumulation of microevolutionary changes can drive evolutionary changes and speciation over time, for example: for speciation to occur isolation is necessarygene: selection of DNA that codes for characteristic ex; hair colourallele: diff forms of gene ex; red hair colourmicro ev- takes place over short periods of time; new forms that arise; example; breed of a dogmacro ev- takes place over millions of years; arising new species; example monkey and humanEvolution of the horseevolution of the horse is microevolutionEvolution of the platypus evolution of the platypus is macroevolution because took a long time and on the way some species were speciated and new species were created.Explain, using examples, how Darwin and Wallace’s Theory of Evolution by Natural Selection accounts for:Convergent evolutiondistinctly related species; shows similarities and moved into similar enviro; exposed to similar selective pressure.Divergent evolutionshare common ancestor; organisms moved to different habitats (exposed to new pressures) another name: adaptive radiation: radiation means spreading out and adaptive means change to their new enviro.Explain how punctuated equilibrium is different from the gradual process of natural selection In 1972, Gould and Eldredge proposed ‘Punctuated Equilibrium.’ This process suggested that species are generally morphologically stable, changing little for long periods of time. This is then ‘punctuated’ by a rapid burst of change that results in a new species due to individuals that have an adaptive advantage in a changed environmental condition. This matches the fossil record. Darwin believed evolution was a slow process, ‘gradualism’, with species evolving and accumulating small variations over long periods of time. The fossil record does not show incremental changes of species. Evolution - the Evidence Inquiry Question 4: What is the evidence that supports the Theory of Evolution by Natural Selection?Investigate using secondary sources, evidence in support of Darwin and Wallace’s Theory of Evolution by Natural Selection, including but not limited to:Biochemical evidence, comparative anatomy, comparative embryology, biogeography and techniques used to date fossils and the evidence produced Explain modern-day examples that demonstrate evolutionary change, for example:The cane toadAntibiotic-resistant strains of bacteriaModule 4 Summary - Ecosystem DynamicsInquiry Question 1: What effect can one species have on the other species in a community?Investigate and determine relationships between biotic and abiotic factors in an ecosystem including:The impact of abiotic factors The impact of biotic factors, including predation, competition and symbiotic relationshipsThe ecological niches occupied by speciesPredicting consequences for populations in ecosystems due to predation, competition, symbiosis and disease. Measuring populations of organisms using sampling techniques.Impact of abiotic factors:Factors:Effect:-Temperature- Types of organisms - Oxygen Availability - Abundance (plants and animals)- Water Availability- Distribution (plants and animals)- Light intensity - Food availability - Buoyancy - Competition - Pressure - Niches- Communities Impact of biotic factors including predation, competition and symbiotic relationships:Biotic factors:Effect:- Availability of food - Abundance (plants and animals)- Competition for territory- Distribution (plants and animals)- Number of predators- Population structure of organisms.- Ability to find a mate- Disease + parasites Predation increases chance of survival or the predator at the expense of the prey and leads to → fluctuating population numbers. Competition is a selective pressure that directly affects relating organisms. Less food → competition → decline in species abundance. Symbiosis occurs when two or more organisms have a prolonged association that may benefit/ harm each member. Eg. parasitism, commensalism, mutualism. symbiotic relationships is the term used for interactions in which a organisms live together in a close relationship that is beneficial to one.· MUTUALISM- both species in relo beneficial (+/+)· COMMENSALISM- one species if beneficial and other unaffected. (+/0) one receiving benefit is called commensal and one that doesn’t get affected is called host. - PARASITISM- one species beneficial and other suffers. (+/-) one receiving benefit is The ecological niches occupied by speciesEcological niche is the relational position of a population in an ecosystem and includes:What it eats.Where it moves.Habitat.Place in food chain.Abiotic + Biotic factors that affect it.> NO two organisms can inhabit the same niche for long periods without some consequence for one of them.Predicting consequences for populations in ecosystems due to predation, competition, symbiosis + disease. the part of the ecosystem that organisms occupies is called niche. Niche refers to all the resources that a species used. 3 types of niches· moderate interspecific (diff species) comp- realistic niche· intense interspecific comp- narrow niche· intense intraspecific (same species) comp- broad nichespecies that are intraspecific are usually more intense as the organisms have more resources common niche overlaps.CONSEQUENCE OF COMPETITION: Comp between species for resources affects reproduction and survival rates. If food sources decrease so may the abundance of both competing species.CONSEQUENCE OF SYMBIOSIS:Symbiosis contributes too increase in biodiversityo development if new speciessymbiosis allows increase in biodiversity and therefore more resilient ecosystemsCONSEQUENCE OF DISEASE:Disease can be defined as any process that affects the normal functioning of the tissues in living organism.Measuring populations of organisms using sampling techniquesCapture-recapture technique used for mobile populations. Traps are set and species are caught, tagged and released. Later the process is repeated and then abundance is calculated. Abundance = total no. captured 1st x total no. captured 2ndNo. tagged in recapture Explain a recent extinction event> Background extinction = the steady turnover for a group of species over periods of geological time> Major mass extinction = complete disappearance of numerous species due to a catastrophic event in a short period of time. Causes of Megafaunal Extinction:Habitat was destroyed from climate changeHunted to extinctionHabitat destroyed by human activity theory one- changes in climate- continent dried out due to ice age- as climate become hotter and drier fires broke out, drier vegetation caught fire easily- rainforests were contracting die to drier climate- animas/ plants died because of no moisturetheory two- arrival of humans- aboriginal people were successful predators- they used fire to blackburn this included burning vegetationthey hunted large animalsPast Ecosystems Inquiry Question 2: How do selection pressures within an ecosystem influence evolutionary change?Analyse paleontological + geological evidence that can be used to provide evidence for past changes in ecosystems. Aboriginal rock paintingsPaintings show animals that were hunted and other activities. Some paintings show extinct marsupials and some paintings show internal features of animals such as heart, skeleton, lungs and organs. This can be used to infer the organisms that lived in the time compared to what we know today.Rock structure and formationDifferent types of rocks form under different conditions. Rock formation can tell about past ecosystems that have since changed. Eg. Many rocks underneath the Nullarbor Plain are limestone. This shows that 20mya the area was a sea as those are the conditions that limestone forms.Ice core drillingIce core drilling is removing ice cores from glaciers and ice sheets. Analysis provides information on the following:Air bubbles of atmospheric gases are trapped provide evidence for past climate changes Solid and dissolved impurities in the waterIsotopes of hydrogen and oxygenInvestigate and analyse past and present technologies that have been used to determine evidence for past changes, for example:Radiometric datingGas analysisRadiometric datingDetermines age of fossils and rocks. Absolute dating → gives a definite age in years, months, ect. Relative dating → gives a non-numerical age but dates the object relative to other substances, older than - younger than. Unstable isotopes change over time in an attempt to become stable → radioactive decay releases energy and the rate at which the decay process occurs is calculated. Compares the abundance of naturally occuring isotope to the abundance of the decay product. Gas analysisLevels of CO2 in the atmosphere → key factor in temperature of the atmosphere. Use ancient levels of CO2 levels to infer past climates. Warming and cooling of the atmosphere → direct effect on biosphere. Analysing gas trapped in ice cores provides data on:Temperature over timeRainfallOcean volumeAtmospheric circulating This provides a wealth of information about past ecosystems on Earth Analyse evidence that present-day organisms have evolved from organisms in the past by examining and interpreting a range of secondary sources to evaluate processes, claims and conclusions relating to the evolution of organisms in Australia, for example:Small mammalsWe can use fossils of past animals to show similarities and differences to present day animals and therefore propose evolutionary relationships between them. When comparing the modern Platypus to fossils → body shape became smaller + more simplified. Can also infer a change in diet as dentition is different. Habitat reduced in size → may have become vulnerable. Example woylie brushSclerophyll plantsEarliest fossils of Eucalyptus pollen → dated 54mya. Fossils of pollen related to existing species → dated 27mya. Earliest fossils of macrofossils → dated 21mya (leaves + bark). This suggests that present day trees evolved from organisms in past organisms. Example golden wattleInvestigate the reasons for a change in past ecosystems, by:Interpreting a range of secondary sources to develop an understanding of the changes in biotic and abiotic factors over short and long periods of timechanges in abiotic + biotic factors → changes in the flora + fauna. Theories for the change in Australian ecosystems include: Continental driftClimate changeThe arrival of indigenous peopleThe arrival of EuropeansThe introduction of non-native plants + animal speciesArrival of humans → extinction for many animals Continental drift → climate cool + wet, rainforest. Australia drifts north, wind patterns change, rainforest contracts with drying climate, rainforests gave way to eucalypts better adapted to the environment. Pathways of ocean currents change, seas change shape → affects heat transfer, therefore climate. Plants able to withstand fire pass genes down → vegetation became fire resistant Evaluating hypotheses that account for identified trends. Inquiry Question 3: How can human activity impact on an ecosystem?Investigate changes in past ecosystems that may inform our approach to the management of future ecosystems, including:The role of human-induced selection pressures on the extinction of specieshumans have affected the environment → influenced the biodiversity. Human induced selection pressures have had an effect on both species and environment. Examples of human induced selection pressures include:Introduced species → rabbit, cane toadPollution → of air water and land Land degradation → compaction, erosion, overuse of fertilisers, logging Habitat destruction → for agriculture, roads, buildingsOveruse of water → desalination, damming of riversOverharvesting of wild stocks → fisheriesRoadkill → effects native animals Models that humans can use to predict future impacts on biodiversity Predicting environmental changes and their impacts of biodiversity → can prevent population declines and extinctions. Methods of this include:Bioindicators are species that show sensitivity to environmental change → used for monitoring the health of ecosystems Representative Concentration Pathways (RCPs) → predict trajectory of greenhouse gas emissions Species distribution models → conservation strategy to keep vulnerable species from extinction Over explosion of resources- refers to harvesting of resources that is not sustainable over time. Example- unsustainable removal of tropical rainforests for timber.Introduced species-causes changes in the relo due to competition, predication, disease. Example cane toad Distribution of ecological relo-. food webs are disturbed due to loss of niches, involve loss of genetic variability. And habitat loss.BIODIVERSITY- genetic diversity refers to intraspecies diversity in traits that makes a population more resilient to enviro change.The role of changing climate on ecosystems Investigate practices used to restore damaged ecosystems, Country or Place, for example:Mining siteBefore mining a reclamation plan is established → land geology, plants, water, soil and wildlife is documented. After mining has finished the area is filled with overburden → earth and rock that were removed earlier and soils. Planting, seeding and irrigation then occurs and the land is monitored. Land degradation from agricultural practices TheoryHumans killed the megafauna Climate Change killed the megafauna DescriptionThis theory suggests that Australian megafauna was hunted to extinction by the first Australians approximately 50 000 years ago.In 1998 David Bowman an ecology expert proposed a theory explaining the extinction of megafauna. This theory suggests that the extinction of megafauna was due to changes in the climate. EvidenceA research team from Monash University drilled sediment cores which held pollen, dust and spores. The team focused its studies on the spores from a fungus called Sporormiella that thrived on the faeces of ancient plant-eating animals. Based on the analysis of these sediment cores researchers were also able to determine when these big animals went extinct and whether there was any significant climate change during the time. Their study found that the demise of the megafauna took place from 45 000 to 43 100 years ago and was not linked to any major changes in climate, vegetation or biomass.A recent study carried out by Vanderbilt University utilized a method called stable isotope analysis of fossil teeth and the diets of extinct mammals. Isotopes of oxygen in tooth enamel vary according to the isotopes in the water that the animals drinks which revealed a trend that the environment was becoming drier. Isotopes of carbon give clues to an animals diet. Evidence has shown that the climate was changing and getting drier and that the animals diets were changing dramatically. This was reflected in carbon isotopes in the tooth enamel. In the younger fossils, diets are more plant based with metabolism known as C3 plants perhaps as a result of the environmental shifts changed the type of plants in the landscape .Conclusion(what do you think is the most likely cause of the Australian megafauna extinction, provide evidence to support your conclusion) The evidence shows that perhaps a combination of human and natural factors lead to the extinction of Australian Megafauna. The drastic change in climate which may have been a likely factor , is supported by the evidence which shows that there was a change in vegetation availability of water. This evidence shows us that environmental factors may have impacted the survival of the megafauna at that time. ................
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