Biology Summary Module 3.docx

Biology Summary Module 3 Effects of the environment on organisms How do environmental pressures promote a change in species diversity and abundance? ### BIOTIC SELECTION PRESSURES THAT EFFECT ECOSYSTEMS - Food availability, predators, competitors, disease organisms, direct human influence...

Biology Summary Module 3 Effects of the environment on organisms How do environmental pressures promote a change in species diversity and abundance? ### BIOTIC SELECTION PRESSURES THAT EFFECT ECOSYSTEMS - Food availability, predators, competitors, disease organisms, direct human influence, - Biotic factors can be from the same or another species - Positive selection pressure for organism = abundance increase - Negative selection pressure for organism = abundance decrease ### ABIOTIC SELECTION PRESSURES THAT EFFECT ECOSYSTEMS - Can be physical or chemical - Availability of water, availability of oxygen and carbon dioxide, light intensity, temperature range, soil characteristics and salinity - Positive selection pressure for organism = abundance increase - Negative selection pressure for organism = abundance decrease **Selection pressures** can affect: - Survival of organisms - Abundance of a population - Diversity of an ecosystem - Evolution of a species +-----------------+-----------------+-----------------+-----------------+ | Ecosystem | Abiotic Factors | Biotic Factors | Examples of | | | | | selection | | | | | pressure on | | | | | organisms | +=================+=================+=================+=================+ | Desert | - Less than | - Sparse | - Lack of | | | 250 mm | grasses and | water keeps | | | | salt bushes | needles | | | - High | | short to | | | temperature | - Spinifex | minimise | | | throughout | hopping | surface | | | the | mouse | area water | | | day (40) | | loss | | | | - Insects | | | | - Low temps | | - Factors | | | at | - lizards | that affect | | | night (0) | | the | | | | | survival of | | | - Often sandy | | an organism | | | soil | | | | | | | | | | - Sometimes | | | | | rocky | | | +-----------------+-----------------+-----------------+-----------------+ | Tropical | - More than | - Wide range | - Plants | | Rainforest | 1500 mm | mammals and | struggle to | | | | insects | get light | | | - High | occupy a | trees | | | humidity | range of | absorb it | | | | habitats | all | | | - Temperature | | | | | s | | | | | mild to | | | | | high | | | | | | | | | | - Dense | | | | | layered | | | | | canopy | | | +-----------------+-----------------+-----------------+-----------------+ | Saline | - Salt levels | - Halophytes | - High salt | | Environments | | | levels | | | | - Mangroves | Toxic | +-----------------+-----------------+-----------------+-----------------+ Investigate changes in a population of organisms due to selection pressures over time, for example: Prickly pear - Introduced into Australia - Took up 10% of agricultural land - Introduced moth to control cactus Short Term consequences of selection pressures - Death - Population is reduced Long term consequences of selection pressures - Adaption/evolution - Population increase ### CANE TOADS IN AUSTRALIA - Introduced as biological control of the cane beetle but wasn't effective. - Has no natural predators, high reproduction rate, suited to Australian environment, broad diet. - The growing population of cane toads is a high selection pressure for Australian marsupials that are prey. **Adaptions** ### ADAPTATIONS OF ORGANISMS THAT INCREASE THEIR ABILITY TO SURVIVE IN THEIR ENVIRONMENT #### Example in animal: #### Example in plant: ### PHYSIOLOGICAL ADAPTATIONS #### Example in animal: #### Example in plant: ### BEHAVIOURAL ADAPTATIONS #### Example in animal: #### Example in plant: Problems associated with inferring characteristics of organisms as adaptions for living in a particular habit 1. Sometimes features are interpreted as adaptions for a particular environment 2. Sometimes you don't know the ecology of the animal and environment ### CHARLES DARWIN OBSERVATIONS ### GALAPOGAS TORTOISE #### Dome shaped Tortoise: No need to raise head for food as the island vegetation abundant and lush so shell remained in dome shape #### Saddleback Tortoise: Have raised saddle like shells that extend towards the front, they also have longer limbs. These adaptations allow them to reach higher for food because the island they were on was more arid and the vegetation was much higher up. These tortoises also had a physiological adaptation as they were now able to digest cacti which was previously avoided.  **Theory of evolution** What is the relationship between evolution and biodiversity? ### BIOLOGICAL DIVERSITY IN TERMS OF THEORY OF EVOLUTION BY NATURAL SELECTION #### levels of biodiversity 1. *Genetic:* Variety of genes within a species 2. *Species:* Variety of species within a habitat or region 3. *Ecosystem:* Variety of ecosystems within a given place Changes come about because of earths physical environment Theory of Evolution - More offspring born will survuve - Offspring will have variations - Struggle for survival - Favourable variations survuve and reproduce - Gardual change new species Biodiversity 1. Genetic diversity - Doversity og genes in a population how many different genes there are 2. Species diversity - How many different species are there more speices = more change of survival 3. Ecosystem diversity Major stages of living things 1. Prokaryotic hetertrophic cells (3500 - 2500 mya) - Obtains food from other organism/chemicals - In oceans 2. Prokaryotic autotrophic cells (2500 - 2000 mya) - Photosynthesis - Chemosytheosis 3. Eukaryotic cells (2000 - 1500 mya) - Very organised - Single celled 4. Colonial groups (1500 - 1000 mya) - Groups of cells together 5. Multicellular cells (1000 -- 500 mya) - Cells do different functions ### HOW AN ACCUMULATION OF CHANGES DRIVES CHANGE AND SPECIATION **Speciation:** Formation of a new species because of geological, physiological, behavioral, or structural factors which prevent previously interbreeding populations from reproducing. **Microevolution**: A change in gene frequency on a small scale within a single population Genetic variation Organisms produce more offspring than is required to replace themselves struggle for survival Microevolution can occur in 4 different ways: - Mutation - Migration - Genetic drift - Natural selection How microevolutionary changes result in speciation When a species splits in to 2 different locations, the groups adapt to different environments with different selection pressures and as a result have distinct changes. Overtime, each species has evolved and changed enough that they can no longer interbreed with each other to produce fertile offspring, meaning they are no longer the same species. Evolution of the horse Hyracotherium - 55.8 -- 33.9 Mya - Pentadactyl limb - Small to hide from predators - Lived in thickly wooded areas - Four visible digits on forefoot, three on hindfoot Mesohippus - 34 -- 23 Mya - Four visible digits - Slightly taller - Drier climate Merychippus - 23 -- 5 Mya - The digits with side digits shorter than the middle one - Increase in height Pliohippus - 5.3 -- 2.6 Mya - Single visible digits - 1m height - Shrubs and grassy plains Modern-day horse - 1.6m tall - A single visible digit Microevolution of a Platypus Feature Non-mammal Mammal -------------------------------- --------------------------------------- ---------------------------------------- Mouth Bill or beak Feet Webbed feet Reproduction Internal fertilisation but egg laying Parental care Mammary glands for milk production Regulation of body Temperature Endotherms Presence of hair Hair is present at some stages of life ### DARWIN AND WALLACE'S THEORY OF EVOLUTION BY NATURAL SELECTION Darwin and Wallace both separately thought of the theory of evolution by Natural Selection. ### CONVERGENT EVOLUTION Convergent evolution is when separate species evolve to become similar due to being in a similar environment and experiencing similar selection pressures. E.g Darwin noted the similarities between the Echidna and the Hedgehog.  ### DIVERGENT EVOLUTION When different species evolve from a similar ancestor when exposed to different environments with different selection pressures. E.g Darwin's finches all came from a common ancestor but evolved due to their different diets and habitats.  ### PUNCTUATED EQUILIBRIUM + THE GRADUAL PROCESS OF NATURAL SELECTION **PUNCTUATED EQUILIBRIUM** Proposed by Stephan Jay Gould and Niles Eldredge in 1972 1. There is a period of stasis 2. Part of the population is separated and experience a strong change in selection pressure = sudden evolutionary change and a new species [Evidence] is when there is a sudden change in fossil record followed by no change for a period. ### GRADUALISM Proposed by Charles Darwin in 1859 Suggests that population slowly diverge by accumulating changes from different selection pressures. [Evidence] is fossil records that show transitional fossil forms.  EVOLUTION -- THE EVIDENCE #### Biochemical evidence: #### Comparative anatomy:  #### Comparative embryology: #### Biogeography: Study of the distribution of organisms. Provides evidence that species originated and when isolated they evolved into new species. ### ### DIRECT EVIDENCE Fossils are direct evidence. The study of fossils is paleontology. #### Where fossils are found: Where sedimentary rocks are exposed. #### Techniques used to date fossils: - Relative dating - Absolute dating *[Relative dating:]* Can determine a fossils age with reference to another fossil (qualitative) by making comparisons between sedimentary layers. Oldest layers are at the bottom. Index fossils can also be used by correlating data. They are fossils that we know an exact date for when they existed. *[Absolute dating:]* Determines a fossils precise age (quantitative) by using radiometric dating which measures the decay of isotopes and their concentration within the fossil. #### Types of fossils: #### Information fossils provide: - Paint a picture of how life on earth formed. - Evolutionary order of species - How species evolved and changing ecosystems - When certain major events occurred e.g., mass extinction  ### MODERN DAY EXAMPLES OF EVOLUTIONARY CHANGE **Applying Darwin's theory of natural selection to modern examples** ##### BASE THEORY: 1. In a population, more individuals are born than survive 2. There is a struggle for survival - not all individuals survive 3. Random Variations (caused by mutation) exist amongst individuals 4. Some have variations (characteristics) that give them an advantage to survive and make them better suited to the environment 5. Those individuals survive. This is called the 'survival of the fittest' 6. These individuals reproduce and the characteristic is inherited 7. Over time, all individuals of the species have this adaptation 8. Over time, with the accumulation of new characters, new species are produced by evolution when populations become isolated from other groups **THE CANE TOAD** Cane toads on the frontier move faster, are stronger and have longer legs (super toads). This allows them to disperse quicker, invade more habitats and produce more athletic offspring however but the super toad also has an increased risk of arthritis. In the 1960's the cane toad distribution was move 10km/year now it\'s moving 60km/ year. ### ANTIBIOTIC RESISTANCE Bacterial strains can develop resistance to antibiotics via the process of Natural Selection. Bacteria that resisted the antibiotics reproduces and passes on their successful genetic material, making the population more resistant.