ECOSYSTEMS

1. ECOSYSTEMS CHAPTER 19 ORGANISATION

2. E1 Populations are the units of the community • E1.1 know that a community is made up of localised, interacting populations: • Life is organised into structural levels • A population- group of individuals of one species capable of interbreeding and producing fertile offspring, that exist in a particular living space/habitat • Community- ALL living organisms found together in a particular living space or habitat

3. ECOSYSTEM: • THE SUM OF ALL –the organisms living in a particular area along with the habitat and the physical components that affect the organisms- e.g. oxygen levels, carbon dioxide levels, water, sunlight soil characteristics etc

4. Ecosystem organisation Communities (The living component Of the ecosystem- made up of various different populations ) • THE ECOSYSTEM IS MADE UP OF POPULATIONS group of the 1 species ORGANISMS TISSUE CELLS MOLECULES

5. Populations/communities that inhabit common environments i.e. savannah woodland or grassy plains-interact with one another • The interactions of a populations with each other (communities) and their interaction with the physical environment =ecosystem • A community is often defined by the common vegetation e.g. River red gum community • Producers- red gums plus?? • Consumers –feed on others for nutrients • Decomposers –feed on dead and decaying material recycling the essential nutrients

6. Plant communities • Differ depending on the most dominant plant type • Forests & woodlands - trees • Scrub- shrubs • Grasslands- usually no trees or shrubs Interactions between organisms can be between members of the same species or members of different species • Three main areas: • Competition • Predation • symbiosis

7. COMPETITION • Organisms compete for same resources-light, space, oxygen and food • Most intense between members of the same species (read this section in text for specific examples) • Some organisms exist quite well together and depending on each species need will mean some have very little competition between different populations

8. PREDATION • One organism feeding on another or eats it • Could be Animal on plant or eating other animals or on occasion plant eating animal • Predation shapes a community-affects the populations numbers of a community-the biodiversity and the evolution of the organisms involved.

9. PREDATORS • Physical characteristics easily observed • Fast • Canine teeth • Agile • Most organisms have defence mechanisms to help them avoid predators. PLANT DEFENCES: -Physical- thorns, spikes, hairs, waxy or silica secretions –all can provide protection against insects -Chemical-some plants produce chemicals that deter herbivores, some have poisonous sap…… (see text)

10. ANIMAL DEFENCES • Chemical- • Again some produce chemicals that deter predators: some poisonous butterflies, the cocktails from spiders, bees, wasps, snakes and other organisms use chemicals to defend themselves Colouration- - The use of colour is very effective as either a warning to others- bright colours can mean toxic -Camouflage- some blend or can hide form predators -Mimicary- mimics or copies the appearance of another species that is known to have protection

11. SYMBIOSIS • Relationships whereby organisms exist with another- three categories: • Mutualism- Lichen lives with algae and fungus- algae provides food and oxygen and fungus the moisture…the relationship between organisms provides survival for all three…. “win win” for all

12. Commensalism • One species benefits only, but other is unharmed • E.g. barnacles attached to razor fish- home for the barnacles and razor fish unharmed Parasitism: -Form of symbiosis the prey is harmed or eaten by something smaller than itself- ticks, fleas, mistletoe and some fungi DO FOCUS QUESTIONS

13. E1.2: Explain that populations in a community consist of different species and know the characteristics that define a species. • Populations in a community are diverse and interact • Species- defined as a population or group where the members have similar characteristics and the capacity to interbreed and produce fertile offspring. • DOES NOT APPLY TO-species that reproduce via asexual means, i.e. single cell organisms (see more explanation in text)

14. SPECIES • Carl Linnaeus-1753 • Binomial system- Genus and species name • Classification- Kingdom, phylum, class, order, family, genus, species • Review The rosella example in text pg 182 ish (large book)

15. E1.3 Give examples of mechanisms that maintain reproductive isolation of a species in a community.(review list in text too) • A mechanism that maintains reproductive isolation means something that is biological and prevents gene flow between different species, even though they may appear similar. • In other words- what stops them interbreeding between species • Barriers that prevent fertilisation: • Pheromone differences • Mating calls • Mating rituals

16. Shape of the genitalia/ flower shape prevents copulation or pollination • Sometimes mating does occur if none of the previous things prevent it, but then the sperm may not unite with the ova • -sperm may be destroyed in the reproductive tract • -Fail to be attracted to the ova • -unable to penetrate the egg • If the sperm does penetrate the ova still other issues can occur • -unequal numbers of chromosomes- foetus does not develop • -occasional success but offspring infertile- (mule) reproductive isolation maintained

17. E2. A community has several trophic levels • E2.1 Give examples of producers, consumers and decomposers in a community • 2 types of nutrition in a community-autotrophic/heterotrophic • AUTOTROPHS-convert inorganic materials into organic molecules-plants-photosynthesis (light energy to chemical energy)- PRODUCERS

18. HETEROTROPHS • -Organisms that must feed on others for survival • -involves eating the organic material of other organisms, digesting the food so that essential requirements are absorbed for use by cells. • Feed on producers- herbivore • Feed on both producers and other heterotrophs-Omnivores • Feed on just other heterotrophs- Carnivore • Review food chains from text-draw a simple one- (consumers/producers etc. 1st-3rd orders)

19. decomposers • - vital in any ecosystem • Bacteria, fungi and earthworms • They obtain their nutrients form dead material at all the trophic levels, includes animal wastes, plant material and dead organisms • The recyclers of the community • Break down organic material and return essential nutrients to the environment

20. Chapter 20 • E3 Characteristics of communities are determined by environmental conditions • E3.1 Describe how environmental factors may determine the type of the community • Each ecosystem has its own producers/consumers/decomposers-the composition of the community is determined by the environmental conditions of the habitat • Different continents and similar conditions will have similar plant communities • Australia- diverse plant communities/large arid areas/variable water levels- subject to fire and high salinity levels

21. Scelerophyll plants • Leaves rigid • Thick and waxy cuticles (ADAPTATIONS) • Acacias and Eucalypts contain these adaptations • Adaptations are needed to enable species to survive the bushfires etc

22. Survival of a species is determined by various factors: • Interactions between other organisms- same species or different • Availability of resources • The climate • Impact of human activities • Each species has evolved features/characteristics that enable its survival in its particular habitat • Various environmental factors shape evolutionary history of species: SUNLIGHT; WATER; TEMPERATURE;NUTRIENTS; WIND; SALINITY; WAVE ACTION…. • WRITE YOUR OWN NOTES ON THESE FACTORS IT IS QUITE OBVIOUS- TABLE PAGE 186 OFFERS A GOOD SUMMARY OF PLANTS AFTER YOUR NOTES ON THE FACTORS

23. E4 Resources are largely recycled in undisturbed communities • E4.1 Understand that the level of available resources will determine the productivity of the community • Resources are classified” biotic or Abiotic • Abiotic for producers includes:- light, rainfall, soil, temperature and nutrient levels • How effective a community is at converting the suns energy is called its productivity-

24. PRODUCTIVITY • of the total amount of energy available/trapped by the producers only a small amount is available to the next trophic level • The producers uses some energy to maintain its own life processes-growth, cell division, uptake nutrients and synthesise molecules

25. Nett primary productivity • Proportion of energy trapped in plant tissue available to consumers • Measured in dry weight- or grams/metre squared/ per year • BIOMASS- refers to total weight of living matter in a community • Productivity obviously various between communities depending on conditions favourable for plant growth: i.e desert vs forest

26. Constraints to productivity • Energy available • Amount and quality or resources • **** humans often use fertilizers and irrigation to boost productivity but can be detrimental to environment • Trace elements in the soil are instrumental in the survival of crops etc

27. E4.2 Explain why decomposers are essential in returning resources to the community • We know all organisms need energy to build tissue • The main elements being • Carbon • Oxygen • Nitrogen • Sulphur • Phosphorus • Potassium and calcium

28. There are about 40 essential nutrients needed by large animals to sustain life. • Matter is neither created or destroyed (remember !) • Therefore we must have ecosystems that can recycle matter • Recycling is done by decomposers • These decomposers Break down matter To inorganic substances To be taken up by plants And recycled

29. Carbon Cycle- pg 190 • http://www.youtube.com/watch?v=9b_95wj3wyg • http://www.youtube.com/watch?v=A98S-BqP4Po

30. Phosphorus Cycle • So we have looked at recycling and Nitrogen and carbon cycle • There is also a phosphorus Cycle • Organisms require much less of this compared to other elements (RARE ELEMENT) • Still essential for existence- Found in Phosphorous Rock • Critical component of what? • Nucleic Acids • RNA and DNA • AS well as part of ATP

31. Phosphorous • As Rocks are weathered/eroded by rainfall • Phosphate released into soil • Taken up by plants • Some have Mycorrhiza that enables them to grow in poor phosphate soils • Animals obtain phosphate by eating plants/other organisms • When animals die- decomposers return the phosphate to the ecosystem • Excess phosphate (fertilisersetc) enters water ways disturbs the natural delicate balance

32. Phosphorous Cycle