1. Biotic Interactions Remember: biotic = living things (in an ecosystem or environment)

2. Holiday homework, revisited • Community = many populations Community: all living things in an area Population = all members of one species living in an area

3. Hol. Homework Cont… • Ecosystem = community + abiotic factors + interactions between components • Naming ecosystems is usually done by describing dominant plant types (eg. An open grassland). Other quantifiers may be added, such as “dense”

4. Hol. Homework cont… • Organisms in community can be grouped into producers, consumers, decomposers Eucalypts: producers Koalas: consumers Grass: producers Snakes: consumers Anaerobic bacteria: decomposers

5. Hol. Homework cont… • Producer: uses sunlight to build organic compounds • Consumer: obtain energy and nutrients by eating other living (or dead) things • Decomposers: break down organic matter to simple mineral nutrients

6. Hol. Homework cont… Consumer groups:

7. Hol. Homework cont… • Guilds are groups of organisms of different species that exploit the same food source Examples: • Birds that eat insects from under tree bark • Nectar eating insects

8. Interactions in ecosystems • Between living community and surroundings Eg. Inputs (oxygen, water, food) and outputs (CO2, urine, faeces) This tree has been shaped by the strong coastal winds. This is an example of an interaction between a living organism and its surroundings Thousands of fish were affected by contamination of this lake

9. Interactions in communities • May be within a species (INTRA-SPECIFIC), or between different species (INTER-SPECIFIC) • Competition • Predator-prey • Parasitism • Mutualism • Commensalism

10. Competition • A fight for resources (eg. Food, shelter etc) • Inevitably, there will be a winner and a loser. Loser must die, leave or change the way it uses resources (niche separation)

11. Examples of competition Male antelope fight for mating resources Adult hippopotami will have territorial fights The penicillium fungus inhibits growth of other organisms by secreting a toxin (penicillin), as a competition for space Faster growing seedlings will shade slower growers, preventing them from receiving adequate sunlight

12. Predator-prey relationships • One species (the predator) kills another animal species (the prey)

13. Predators vs prey The green python hunts for tree dwelling animals, like birds, bats and small mammals at night. It senses them using heat sensing pits. It constricts its prey. Spider weaves a web, which is sticky and catches flying insects. Spider may also have venom.

14. Herbivore-plant relationship • Some plants prevent being eaten. They may do it by: • Tasting or smelling terrible • Having poisonous structures • Having thorns/spikes • Stinging with nettles

15. Parasite-host relationships • One organism (parasite) lives on or in another (host). • Parasite is benefited, while host is harmed in some way • ON host = exoparasite • IN host = endoparasite

16. Parasites and their hosts Mistletoe grows on and inside a eucalypt. It takes its nutrients, but appears as a healthy part of the tree The mouth of a parasitic flat worm, which attaches to a host’s skin (humans!!), and enters their bloodstream A fully engorged paralysis tick. These feed on the blood of mammals, and can cause paralysis of the muscles around where it enters the body.

17. Mutualism • An interaction where both organisms benefit in some way Bacteria living in the lure of an anglerfish get a stable environment, while the anglerfish is a more efficient predator The mistletoe bird eats mistletoe berries. Before they defecate, they turn their bodies parallel to the branch, which means the seed does not fall to the ground, but gets lodged in the branch Nitrogen fixing bacteria lives in the root nodules of some plants. These bacterium remove nitrogen from the air and turn it into a usable compound for the plant.

18. Commensalism • One member of the interaction benefits, while the other is neither harmed nor benefited. Anenome fish make their home within stinging anenomes. They are immune to the sting, but it keeps predators away. The anenome, though, will have the same quality of life with or without the anenome fish

19. Symbiosis • These interactions are called SYMBIOSIS

20. Activities Glossary words: inter-specific, intra-specific, competition, predator, prey, mimicry, camouflage, parasite, host, exoparasite, endoparasite, mutualism, nitrogen fixing bacteria, commensalism, symbiosis. Quick Check pg 433