Effects of the Environment On Organisms
Inquiry Question: How do environmental pressures promote a change in species diversity and abundance?
Combination of all the organisms, biotic and abiotic, living in a community and how they interact
Organisms with favorable characteristics/adaptations that are uniquely suited for that ecosystem will ultimately survive better
Diversity and abundance is due to variation in biotic and abiotic factors
Environment refers to the surroundings or dwelling place of all living things → habitat or setting
Abiotic factors directly influence selection pressures on organisms
Found on land
Dessert, grasslands, forest, Woodland
Wetlands, Mangrove swamps, estuaries, rivers, lakes
Salt concentration, light availability
Selection Pressures in an Ecosystem
- Selection pressures are all the factors of an ecosystem that influences changes of survival
Natural selection is a process whereby species which have traits that enable them to adapt in an environment survive and reproduce, and then pass on their genes to the next generation.
Drives natural selection
Those individuals within the population that have random variations that make them better suited to survive in the changed environment are more likely to survive
Genetic based variation are passed from presurvung parents to offspring
Biodiversity is essential for a surviving population → If all organisms were the same, no organisms could adapt to new conditions. - Abiotic pressures:
Abundance and Distribution
- Abundance → How many individuals of that species live throughout an ecosystem
- Distribution → Where it is found
Both abiotic and biotic factors affect these
- The study of interrelationships between different types of organisms and between organisms and their environment.
Determines the distribution and abundance of flora and fauna
Determines measures of populations in areas
Studies the patterns that are formed → Increase or decrease in population
What factors influence the distribution and abundance of populations in ecosystems?
Measuring Plant Abundance
- Non mobile organism are easier to collect data about
120 daises have been collect in 10 1mx1m quadrats. What is the estimated abundance of daises in that area
(120/1x10) x 800
Measuring Animal Abundance
- Mark, Release, Capture
- First sample, 20 individuals were marked. Second sample 50 were collected, 10 were marked.
- Examining population trends can lead to inferences about the species and what abiotic and biotic characteristics they are most suited too.
Changes in Populations Over Time
- Members in population that survive and reproduce in their habitat carry the traits most suitable for the conditions
- Introduced to Australia in 1935 to control the greyback cane beetle in sugar plantations
Increasing at a fast rate
Specific structural adaptations and behaviours to suit Australia
Feed at night, no predators, breed all year, absorb water through
The Cane Toads are evolving to be faster, but more prone to arthritis
Predators have increased resistance to the toxin and those reluctant to eat cane toads are ones that survive and reproduce
Red Belly Black snakes have gotten smaller due to the inability to consume the frogs → Snakes big enough to eat them die due to the toxin
The Northern Quoll has developed a Toad aversion mechanism to avoid the consumption of the toads
- Prickly Pear
- Introduced to Australia to start cochineal dye industry
Due to the lack of environmental pressures prickly pears spread at a rapid rate
Nonetheless, due to the lack of biodiversity, introducing a moth provided a strong selection pressure that quickly reduced the numbers and distribution of the prickly pears.
Inquiry Question: How do adaptations increase the organism’s ability to survive?
- Organisms are adapted to survive in their natural environment as a result of evolutionary change by natural selection
An adaptation is a characteristic that an organism has inherited and makes it suited for its environment
It is a result of change that arise via mutation, when a cell divides and replicates during the process of reproduction
How an organism is built
How an organism functions
How an organism acts and behaves
Structural Adaptation- Plants
- Desert plants are able to balance photosynthesis and water for cooling purposes without risking dehydration
Xenophytes → Structural adaptations to maximise absorption and storage or water and minimal loss of water
Eucalypts → Waxy leaves to minimise transpiration of water and exposure to sunlight
Cypress Pines → Tiny cylindrical leaves to have a small SA:V ratio
Structural Adaptations- Animals
- Thorny Devil
- Has spikes on its body to make it look more ferocious as well as being harder to swallow by prey
Has scales that absorb water straight into its mouth
Gold and brown camouflages in dessert
- Muscular shoulders and large claws used for extensive digging - Pouch to protect joeys from dirt whilst digging
Physiological Adaptations- Plant
- Salt tolerant plants are able to maintain metabolic functioning through their cells accumulate sodium and chloride ions
Minimise salt toxicity by increasing water content in vacuole
Physiological Adaptations- Animal
- Penguins, seals and polar bears convert a lot of their diet to a fat layer to insulate them from the cold
- Some animals slow down their metabolic rates so their overall temperature is cooled
Cane toads dig a water tight mucus cocoon for cooling
Behavioural Adaptations- Plant
- The venus flytrap has adapted to live in nitrogen-poor soils which it obtains via insects
It can act rapidly when it detects an insect
Insect becomes trapped and the plant absorbs its nutrients
Behavioural Adaptations- Animal
- Puffer fish pumping air into their stomachs and blow up twice their size to frighten predators
Penguins route in packs to reduce time spent in the cold
Darwin in the Galapagos Islands
- Dariwn observed small ground finches on the Galapagos Islands
The shape of their beak was observed → Size of beaks differed
Naturally occurring changes in colour, beak size and leg length
- Depending on which island they lived on, and the conditions they found themselves in, some birds thrive and reproduced - Charles Noted:
There is a variation in all populations with many variation heritable
There are more organisms born then the environment can sustain
Those individuals that have more suitable characteristics survive
Survivors pass on traits to offspring
- Favorable traits will become more numerous if the environment is stable
Survival of the Fittest
- Variation exists with more population
More offspring are produced that can survive
The offspring better adapted will survive and reproduce
The favourable characteristics are passed on
Overtime favourable characteristics will increase in the population
Theory Of Natural Selection
Inquiry Question: What is the relationship between biodiversity and evolution?
- The Theory Of Evolution By Natural Selection
Diversity allows adaptations to change in an environment
- Species have been developing for billions of years
- All theories of evolution share a common basic premises
Living organisms arose from common ancestors or a common life form and have changed over time
Differences that occur among groups of living organisms imply that living things change over time
Similarities occur in living things and suggest a common ancestry; the basic chemistry, inherited from a common life form, has remained relatively unchanged and has been passed down through generations.
- The variety of forms of life on Earth, the diversity of the characteristics of living organisms and the variety of their ecosystems.
Diversity allows for adaptations
Three levels of biodiversity
Genetic → Genetic makeup in a species
Species → Measure of the diversity of species
Ecosystem → Variation of different ecosystems
- Important for the population to be able to adapt
Environments are constantly changing and pose selection pressures that enable some organisms with favourable characteristics to survive and reproduce
No variation in the population will be more detrimental for an invasive organism or pressure
More genetic diversity = more chance of survival
Concept of Natural Selection
- Organisms must possess traits that favor their survival in that environment
- [Variability] → All populations have random differences or variations among members
- [Heritability] → Variation must be inherited
- [Over Reproduction] → Organisms produce more offspring than what the ecosystem can sustain
- [Competition] → The best suited traits will ultimately thrive and reproduce
- If there is a sudden change in the environments, those individuals that randomly possess a variation that is an advantage are more likely to survive the changed conditions
Diversification of Life on Earth
- The move form unicellular organisms to multicellular organs began when these cells clustered together
Life began to diversify further with a rise in invertebrates to fish and amphibians
Followed by the dominance of reptiles
Mammals species then began to dominate
Selection pressures lead to the thrive and extinction of species
Microevolution vs Macroevolution
- Macroevolution → Takes place over millions of years, usually results in new species
- Microevolution→ shorter periods and results in changes of a particular species, but does not create a new species
Small changes can lead to a dramatic difference
New varieties or races (Dog Breeds)
Evolution Of The Horse
- Has a complete fossil record
Mammal belonging to the family Equidae
- Evolved over 50 million years from a dog-sized, forest-dwelling animal Hyracotherium
Shares a common ancestor with tapirs and rhinoceroses
Horse evolution has a branching nature (rather than a linear evolution)
The fossil record showed there were several different migrations, changes in trends from smaller to larger sizes as well as reduction in size. The rate of evolutionary change did not appear to be constant.
Fossils have shown changes in body size, number of toes and dentition (teeth - development of grinding surfaces)
Genetic variation caused by mutations, natural selection, genetic drift and speciation have all contributed to the evolution of the horse
Microevolution can occur when a series of mutations leads to a change in gene frequency in a population. This change in the gene pool is due to chance and is called genetic drift. If a population becomes isolated speciation might occur.
A small population with a mutated gene may become separated from the main population, causing the mutated gene to increase in the population as interbreeding occurs. If the change is favourable it is selected for (it increases chance of survival)
The isolated population evolves to become significantly different from the original population and eventually if brought back together they would not be able to interbreed, resulting in the formation of a new species.
Evolution Of The Platypus
- Platypus shows similar features to birds, reptiles and mammals - Webbed feet, venom gland, hair on body
Genetic evidence suggest that monotremes split off first evolved
The first split was between marsupials and mammals
Platypus and echidna share common ancestors
Very well adapted to the environment it lives in
Lay an egg with yolk
- Platypus can located prey with their eyes closed, by sensing electric pulses given off by muscles
- A type of macroevolution
Convergent Vs Divergent Evolution
Distantly related species which have moved to similar environments and are exposed to similar selection pressures to evolve similarly
Similar habitats, similar variation would be favoured by natural selection to enable them to survive
- Ancestral species radiates into a number of descendant species with both similar and different traits
Usually influenced by various selection pressures
An example is Darwin's finches
Gradual Natural selection vs Punctuated Equilibrium
- Populations slowly diverge by accumulating changes in characteristics due to selection pressures
Suggest that transitional forms should exist
- Occurs in short bursts of rapid change, followed by long period of stability within populations
- Mutations are passed on
Evolution- The Evidence
Inquiry Question: What is the evidence that supports the Theory of Evolution by Natural Selection?
- All living things share the same macromolecules such as proteins and DNA and biochemical process such as cellular respiration
Biochemistry is the study of chemicals found in sound
More closely related species have more similar DNA and proteins
Similarities imply they had a common ancestor
Amino Acid Sequencing
Proteins are a component of all living organism
Made up of amino acids
- The sequence of amino acids in the protein is analysed and similarities and differences between organisms are identified.
- Differences imply the organism has evolved.
- Number of differences is proportional to the length of time since the organism separated
Samples of DNA are removed from two different organism
The separated strands of the species to be compared are then mixed.
- The two strands combine (reassociation) and form a ‘hybrid’ DNA molecule
- The more closely matched the DNA, the tighter the binding.
- Heat is applied to determine how tightly the DNA strands have combined. More closely related species have more similar sequences of bases and therefore the strands bind tightly.
- DNA Sequencing
- The exact order of bases in DNA of one species is compared with a similar fragment of another species.
A piece of DNA is isolated from each organism.
Multiple copies are made, and dye is used to label the bases.
- A DNA sequencer is used to graph and print out the sequence of bases, which are then compared.
Organisms that share a common ancestor share fewer differences.
Provides more detailed information than other biochemical methods.
- Comparative Anatomy
- Study of similarities and differences in the structure of living things
More similarities imply the organism have separated from a common ancestor recently
Homologous Structures (Divergent Evolution) - Differences in structure represent modification.
Organisms that have the same basic plan to their structure but show modifications are called homologous – they have the same evolutionary origins.
- Analogous Structures (Convergent Evolution)
- Structures that look similar but are very different (e.g. wings of bird and wings of grasshopper)
May have started off differently but over time evolve to look similar.
E.g. Australian Echidna and European Hedgehog
- Do not show evolutionary relatedness – shows the evolution of structures for a common purpose.
- Vestigial Structures
- Evolutionary remnants of body parts that no longer serve a useful function.
Provides evidence of common ancestry.
E.g. presence of coccyx and appendix in humans.
- Comparison of development stages of an organism
Related species show similarities in development
Fish, mammals, amphibians, birds
- Study of the distribution of organisms
For a new species to arise, it must be genetically isolated.
- Fossils provide direct evidence of the existence of an organism in the past
- The sequence in which fossils are laid down in a rock reflects the order in which they were formed
Law of Superposition
Further down in a rock represent an older fossil
Relative dating relies on the assumption that the fossils higher up in the rock are younger than the lower fossils → Fossils are dated relative to one another
Absolute dating enables the actual age of the specimen to be determined by using radioactive elements that are present
Modern Day Evolution
- Cane Toad
Faster and larger cane toads have reproduced more, hence the whole population is slowly getting faster
Red-belly black snakes have developed a smaller mouth so they are incapable of consuming the organism
There are no selection pressures on the cane toad, hence they will be able to continue to reproduce at exponential rates.
- Antibiotic resistant Bacteria
Antibiotics are chemical that inhibit the growth of bacteria or destroy them → Target cell wall and inhibit cell metabolism
When penicillin and other antibiotics were introduced the threat posed by infections was reduced
However, strains of bacteria has developed that are not affected by antibiotics
- The bacteria that survives passes on genes which leads to a whole new variation of bacteria
Module 4 - Ecosystem Dynamics
Inquiry Question: What effect can one species have on the other species in a community?
Organisation within ecosystems
- Biosphere contains all the living thighs on Earth
- Environments can positively or negatively impact an organism - An organism living and non-living surrounds its ecosystem
Impact of Abiotic Factors
- Abiotic factors are not easily disturbed
Own unique way of thriving within the limits of the abiotic environment
Water is a very effective filter of sunlight
Rapid drop in temperature
Impact Of Biotic Factors
- Living organisms can affect each other by predation and symbiosis but also have an equally profound effect on resources
Food sources, mates, light, nutrients, water
Predator obtains its food by killing and eating another animals
Found in aquatic or terrestrial ecosystems
Spider capturing bugs in its web and eating it
Competition is usually for a resource in the environment that is limited supply but valuable for survival
- All competition involves risk to the competitors and the rewards must outweigh the inherent risk
Intraspecific → Within a species
Interspecific → Between species
- Interactions in which two organisms live together in a close relationship that is beneficial to at least one of them
Obligate relationship → species depend on each other to live
Both organism benefit
- Clownfish and sea anemone → Clown fish is protected by the sea anemone whilst the fish cleans the plant
One species is benefited whilst the other is not harmed or helped
Birds that live in hollow holes in trees
One species benefits whilst the other is harmed
- Parasite obtains shelter from the host organism while feeding upon the tissue and fluids
Ecological Niches occupied by Species
- The part of an ecosystem that the organism occupies is called a niche
Refers to all the resources that a species uses, including biotic and abiotic
The process of having unique living strategies
Fundamental niche → The perfect conditions and resources for an organism to live and reproduce
Realised Niche → All the aspects of the ecosystem including the interactions of other species
Consequences in ecosystems
Effect the distribution and abundance of prey
If the prey can reproduce fast enough, rates wont drop
- Prey and predators are in direct proportion
Effects reproduction and survival rates
More food sources → More abundance of both species
Different traits will boost a species survival of getting resources
Increased evolutionary diversification
Development of new species from the integration of genetic material
More resilient ecosystems → Biodiversity
- Any process that adversely affects the normal functioning of tissue in a living organism
- Bacteria, virus, Pathogen
- Alter the balance of food webs → Affected species will decline in numbers
- Continent dried out
Rainforests were contracting – stored moisture and returned moisture to the atmosphere.
Eucalypt forests replaced these, and water was not as efficiently retained.
- Became hotter and drier, fires broke out due to lightning.
- Plants and animals that survived the drought and fire reproduced, changing the flora and fauna.
Arrival Of Humans
- Aboriginal people arrived successful predators.
Used ‘fire stick’ farming techniques.
- Introduction of dingoes may have reduced the diversity of carnivore predators.
Level Of Nutrients
- Low level of nutrients in the soil → dry
Led to smaller animals →F can be sustained on less
- Evidence for this can be seen in the smaller size of mammals in Australia compared to counterparts across the world.
Inquiry Question: How do selection pressures within an ecosystem influence evolutionary change?
- It is unclear when humans first became interested in fossils.
Philosophers hinted that fossils were evidence of previous life.
Law of superposition → oldest layer at bottom and newest at top.
Aboriginal Rock Paintings
- Longest unbroken tradition in the world
Humans are driven by nature to record details of their existence
West Kimberly’s rock paintings
Radiometric dating is used to date the paintings
- Uranium/Thorium can be used to underlying calcite formations to show when they were formed
Types and abundance of animals depicted in paintings changed overtime
- Allows reconstruction of timeline of events
Represents the course of changes in geological and fossil deposits
Banded iron Formations
Form of geochemical evidence found in Australia
- Earth's atmosphere has undergone changes, change from anaerobic to aerobic
- Form of iron rich and iron poor sediments
Prokaryotes lead to an increase in oxygen concentration in the ocean, leading to precipitation of insoluble iron oxide
Precipitate accumulated at the bottom of the ocean, forming an iron rich layer of sediments
- Great oxygenation event transformed Earth’s atmosphere
- Resulted in much larger and multicellular organism→ Organisms had to adapt to more oxygen
- Palaeontological Evidence
Fossils offer clues to the selection pressures of living things like the climate and environment at the time
Found in sedimentary rocks → Preserve evidence rather than destroying it
Fossilised soils contain large concentrations of carbon that indicate presence of life
Chemosynthesis is a process where organisms use inorganic compounds available from their environment.
The fossils formed from stromalites provide valuable informationof early orgaims and the environment in which they lived
Ice Core Drilling
- Accumulation of ice layers in places such as antarctica leaves an annual record of gas and dust in that atmosphere of that time
- Scientists can drill into the ice, extract gases and reconstruct the climate record
Increases understanding of past environments
- Process where scientists determine the age in years of a fossil, rock or mineral
Based off the content of radioactive isotopes
- Unstable isotopes change to form stable isotopes → Undergoes radioactive decay which scientists can compare to examine the life of the rock
- More half lives → Older
- Rate of decay is calculated using the age equation that compares the abundance of the naturally occurring isotope with the abundance of the decay product.
- Scientists can use data in ice cores to reconstruct atmospheric concentrations of certain gases, particularly CO~2~ and O~~ 2.
CO~2~ is a normal part of Earth’s atmosphere along with nitrogen, oxygen, argon and other trace gases
But CO~2~ is also considered a ‘greenhouse gas’ that traps solar radiation keeping the Earth warm enough to sustain life
However, increasing CO~2~ in atmosphere is likely to increase Earth’s atmospheric temperature, known as the ’enhanced greenhouse effect’ or ‘global warming’
Scientists use ancient CO~2~ levels~~ to infer past climates - warming or cooling would have a direct effect on the types of plants and animals that are suited to survive in such a climate
Oxygen has three naturally occurring isotopes: ^16^ ^^O, ^17^ ^^O and ^18^ ^^O which are incorporated into water molecules. The ratio of ^18^ O/^^^16^ ^^O in analysed ice core samples indicates ancient water temperatures which scientists can use to reconstruct water temperatures on Earth.
- We Can use fossil 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.
We can infer a change in diet as dentition is different
Habitat reduced in size → May have become vulnerable.
Reasons for Change
- Australia’s change in climate due to the split of Gondwana
Arrival of indigenous
- Introduction of non native plant + animals → invasive species → Destroys or affects the natural food web
Inquiry Question: How can human activity impact an ecosystem?
Human Induced Species
- Increasing Population
Selective breeding, use of fertilisers, pesticides and herbicides
Medical breakthroughs with antibiotics, better hygiene and vaccinations
Increasing populations of humans lead to an increase of the demand of resources from ecosystems
Selective breeding limits the biodiversity of species, hence making them more susceptible to being majorly effected by disease or change
- Removal of trees leaves the soil vulnerable to erosion → Loss of valuable minerals for an ecosystem
Pollutions harms the water and atmosphere
Irrigation was developed alongside the domestication of plants
- Selective breeding of crops and livestock radically altered their features to favour large yields
- Introduced Species
Many invasive species out compete native species for light, water, habitats and nutrients
Change the environments to alter the microclimate of the areas to favour their own development
Completely alter the food web system which has detrimental effects on the rest of the ecosystem
- Land Clearing
Refers to the removal of native vegetation for urban and agricultural development
Removes nesting and habitats of native animals → Cannot reestablish anywhere else.
Habitat loss is the leading cause of extinction
Most historic extinctions have occurred on islands because a small habitat loss has devastating effects
Extinction opened niches for surviving organism to expand into → Rapid development of species
Past To Inform the Future
- Can estimate rates of extinction by studying recorded extinction events, examining fossil record and by analysing modern trends in habitat loss
Over exploitation of resources → Harvesting an amount that is not sustainable over time
Introduced species → New species effect relationships due to competition, predation and disease
Disruption of ecological relationships → loss of available niches alter the distribution and abundance of species
- Genetic diversity → Intraspecies diversity in traits that makes a population resilient to environmental changes
Species Diversity → Variety of species in an ecosystem
- Ecosystem diversity → Variety of ecosystems available in a broader area such a continents or globally
- Greenhouse Effect
Solar radiation reaches and penetrates earths atmosphere
Some energy is trapped and absorbed into the land and ocean
Keeps earth warm and sustainable
Increase of concentration of greenhouse gases
More energy being absorbed in oceans and land
External factors → Solar input from the sun, Earths variety in orbit
- Internal factors → Active release of CO2 from volcanoes, diffusion of CO2 from ocean, less reflection of light from ice (Melting ice is bad)
Human Factors → burning fossil fuels, agriculture, land clearing
Models Predicting Biodiversity
- Resources increase slow
Humans grow quick
Humans will outgrow their ability to feed themselves
Greater fertility will lead to starvation
Keep numbers and population in check
- Required to follow laws and strict guidelines, which include submitting information on how they intended to ensure minimal harm to environment
- All mining companies must complete an environmental impact statement as a part of their license application
Land Degradation and Agriculture
- Marked improvement in the management of Australiansoils and waterways
Farm owners can have their land inspected by scientists
Management of salinity and erosion are high priorities
Biological controls are being used to maintain pests