1. V.C.E. Biology Unit 2 Area of Study 2 Dynamic Ecosystems Chapter 13 – Ecosystems and their living environment

2. Key Knowledge  Identify the components of an ecosystem  Understand the nature of a living community  Become aware of the various ecological roles in a community  Understand the variety of interactions that occur within an ecosystem

3. Community A community is all the different species living together in the one habitat. Each community is made up of populations living at the same location at the same time. All the different populations living at one location at a particular time form a community: community 1 = pop 1 + pop 2 + pop 3... so on Communities in different ecosystems can vary in their diversity. Diversity is not simply a measure of the number of different populations (or different species) present in a community.

4. Diversity When ecologists measure the diversity of a community, they consider two factors: 1. The richness or the number of different species present in the sample of the community, and 2. The evenness or the relative abundance of the different species in the sample As richness and evenness increase, the diversity of a community also increases.

5. Populations Each population consists of one species that may be a different species of animal, plant, fungus, protist or microbe. A population is defined as all the individuals of one particular species living in the same area at the same time.

6. Ecosystems An ecosystem consists of a community, its physical surrounding, and the interactions between and within them. The study of ecosystems is the science known as ecology. Each ecosystem includes a living part and a non-living part. The living (biotic) part is a community that consists of the populations of various species that live in a given region.The non-living (abiotic) part consists of the physical surroundings. Ecosystems can vary in size, but must be large enough to allow for the interactions that are necessary to maintain them. An ecosystem may be as small as a freshwater pond or a terrain as large as an extensive area of mulga scrubland in inland Australia.

7. Naming ecosystems Ecosystems are generally named on the basis of the dominant vegetation. E.g. ‘an open grassland ecosystem’ ‘tall closed forest ecosystem or naming can be more specific E.g. ‘a tall open Eucalyptus forest ecosystem’

8. Ecological communities If we look at a variety of ecosystems, we find that the living community in each ecosystem differs. The various populations that make up each community have physical, biochemical and behavioral features that equip them for survival and reproduction in the particular environmental conditions of their ecosystem.

9. Ecological communities Your Task Read pages 411-414 ‘The community of a littoral zone’ ‘The community of an open forest’ ‘The community of a Mallee ecosystem’ Construct a table which outlines the major featues of the environment and outline the physical, biochemical and behavioral features of the fauna that equip them for survival and reproduction in the particular environmental conditions of their ecosystem.

10. Ecological groupings within an ecosystem The living community of different ecosystems, re apparently very different in terms of the species that are present. However, there is a common pattern to each community. Members of every community can be identified as belonging to one of the following ecological groups: producers or autotrophs; consumers or heterotrophs; decomposers

11. Producers - Autotrophs The community in every functioning ecosystem must contain some species that can be identified as producers or autotrophs. Producers or autotrophs are the members of the community that can manufacture their own organic compounds, such as glucose, from simple inorganic compounds, such as carbon dioxide, using an abiotic source such as sunlight.

12. Producers - Autotrophs This chemical energy is them made available, either directly or indirectly to all other members of the living community of that ecosystem. The process by which most producers transform the radiant energy of sunlight into the chemical energy of sugars is known as photosynthesis: light energy carbon dioxide + water glucose + oxygen (LOW ENERGY) (HIGH ENERGY)

13. Producers - Autotrophs In aquatic ecosystems, such as seas, lakes and rivers, the producers are microscopic phytoplankton, microscopic algae and seagrasses. In terrestrial ecosystems the producers include trees, grasses and other flowering plants, cone bearing plants (e.g. pines), and other kinds of plants such a ferns and mosses.

14. Consumers - Heterotrophs Consumers or heterotrophs are those members of a community that must obtain their energy by eating other organisms or parts of them. All animals are consumers! Consumer organisms can be subdivided into the following groups: - herbivores that eat plants (wallabies and koalas) - carnivores that eat animas (numbats and snakes) - omnivores that eat both plants and animals (humans and bears) - detritivores that eat decomposing organic matter such as rotting leaves, dung or decaying animal remains.

15. Consumers - Heterotrophs Particles of organic matter are called detritus. Detritus is made up of dead leaves, animal remains, animal faeces etc, in short, all organic matter that contains chemical energy. Detritivores are animals that eat detritus. They differ from decomposers as they release enzymes onto the detritus, partially breaking it down, and then they absorb some of the products.

16. Decomposers Typical decomposer species in a community are various species of fungi and bacteria. Decomposers are heterotrophs that obtain their energy and organic matter and in this case, the ‘food’ is dead organic material. Decomposers differ from other consumers because as they feed, they break down organic matter into simple inorganic forms or mineral nutrients, such as nitrate and phosphate.

17. Decomposers So, decomposers are extremely important to the environment as they convert organic compounds to inorganic compounds which the producers need. They are also important as they break down the wastes or consumers, so that they don’t build up. This is the cycling of matter in an ecosystem.

18. Interactions within an ecosystem In ecosystems, interactions are continually occurring:  between the living community and its abiotic surroundings  within the abiotic surroundings  within the living community

19. Organisms and their surroundings  Refer to figure 13.18 p419 List the interactions between the environment and: a) The Tasmanian devil b) The Daffodil

20. Within abiotic surroundings  Use the example of a storm to show the effects that some abiotic factors have on other abiotic factors within an environment

21. Interactions within a living community  Competition  Predator-prey relationships  Parasitism  Mutualism  Commensalism

22. Symbiosis  Symbiosis is the term we use to describe when different species live together in a relationship.  The relationships can be classified as: - parasite-host - mutualism - commensalism

23. Competition Competition occurs when organisms living in a community are competing for the same resources. Competition may occur between:  members of the same species – intra-specific competition  members of different species – inter-specific competition Read p421-422 and explain how some strategies animals use to combat competition.

24. Predator-prey relationships Where one species, the predator, kills and eats another animals species, the prey. Prey species have adapted strategies to help them avoid being caught:  Structural features – camouflage, mimicry.  Behavioral features – keeping still, having a sentry (lookout), schooling  Biochemical features – produce repellant or toxins (often signaled by bright colouration)

25. Herbivore-plant relatonships Herbivores obtain their nutrients from eating plants. But plants do not want to be eaten… so what can they do?  To deter predators, plants can produce: - spines, spikes or thorns - chemicals, toxins or poisons  To deter other plants from growing in their space: - chemicals to inhibit the growth of other plants in the area

26. Parasite-host relationships Where one species, the parasite, feeds and lives off the other species, the host. Exoparasites live on the exterior of the body e.g. fleas, ticks. Endoparasites live inside the body e.g. intestinal or heart worms. In parasitism, the parasite harms the host in some way, but does not generally kill it. Why?

27. Parasite-host relationships  In plants, there are two main types of parasite-host relationships: 1) halo-parasitism – the parasite is totally dependant on the plant for all its nutrients (very rare e.g. Genus Rafflesia) 2) hemi-parasitism – the parasite obtains some nutrients from the host, but can also make its own food (e.g. mistletoe species)

28. Mutualism  A relationship involving two different species where both species benefit from the relationship. Provide two examples. Commensalism  A relationship where one animal benefits from the relationship, and the other neither benefits nor suffers. Provide one example.

29. Minimising competition between species  Organisms need to not be in direct competition with each other for every resource they require.  When various species in the same community differ in the use that they make of a resource, such as food or space, the various species are said to show niche separation.  The greater the niche separation between the two species, the smaller the level of competition between them.  If however, two species use the same resource in similar ways, they can be said to show niche overlap.  The greater the niche overlap, the greater the intensity of competition between the two species.

30. Questions  Answer the following ‘quick-check’ questions: Questions 1 & 2 – Page 411 Questions 3 & 4 – Page 419 Questions 5 & 6 - Page 433.  Biochallenge – Page 434  Chapter Review Questions – 2, 4, 5 and 7