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Interaction in Ecosystems. Symbiotic Relationships “a set of relationships between individuals of different species ”. 3 types of symbiotic relationship. Parasitism. -where one partner (the parasite) benefits and the other is harmed (the host). Parasites may be:
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Interaction in Ecosystems Symbiotic Relationships “a set of relationships between individuals of different species”
Parasitism -where one partner (the parasite) benefits and the other is harmed (the host). Parasites may be: • obligate (ie completely dependent on the host) • facultative (ie can survive without the host)
Parasites may be….. ...endoparasites, which live inside the body of the host. They tend not to kill their host. Example: Tapeworm
Parasites may be….. • …….. ectoparasites, which live on the outside of the host. Example: Fleas
Transmission of Parasites to New Hosts.Method 1 • Direct contact eg head lice
Transmission of Parasites to New Hosts.Method 2 • Resistant stages eg liver fluke larvae
Transmission of Parasites to New Hosts.Method 3 • Vectors and secondary hosts eg cat tape worms and mice. • The eggs of a tapeworm living in the gut of a cat passes its eggs with the cat faeces. These may fall amongst grain which the mouse inadvertently eats. The eggs hatch into larvae inside the mouse which if eaten by a cat starts the process all over again.
ParasitismFurther Reading • Environmental Biology Monograph pages 20/21 • DART Environmental Biology Notes pages 32/33 • Trials of Life by David Attenborough pages 176 - 184
Commensalism • ‘one partner benefits whilst the other remains unaffected’ • The relationship is usually based on feeding and/or protection.
CommensalismExample 1 • Shark and Remora. The Remora feeds on scraps out of the shark’s mouth. The shark gets no benefit or harm.
CommensalismExample 2 • eg two toed sloth and slothy moths. The moths get a free ride to find mates and lay their eggs in the droppings of the sloth. When the caterpillar hatches it feeds on the droppings. The sloth is unaffected.
CommensalismFurther Reading • Environmental Biology Monograph, page 21 • DART Environmental Biology Notes, page 34 • Trials of Life by David Attenborough, pages 170 - 173
Mutualism • ‘where both partners benefit.’ • Very common • Often involves exchange of metabolic products • Often close structural compatability
MutualismExample 1 Eg Warthog and oxpecker. The oxpecker gets a supply of food and the warthog gets rid of parasitic ticks.
MutualismExample 2 • Eg leguminous plants and Rhizobium bacteria. • The plant gets a supply of nitrate and the Rhizobium gets provided with leg-haemoglobin to limit oxygen supply.
Mutualism Example 3 • eg sloths and algae. • The algae provides camouflage--giving the sloth a greenish tinge to match tree foliage. It also provide nutrients, which the sloth eats by licking or is absorbed directly through the skin. • The algae are provided with a habitat and moisture when the sloth licks the skin
MutualismFurther Reading • Environmental Biology Monograph, page 22 • DART Environmental Biology Notes, pages 35 – 36 • Trials of Life by David Attenborough, chapter 7 ‘Living Together’ • Animal Watching by Desmond Morris, chapter titled ‘Mutual Aid’
Symbiotic Relationships • Now watch the ‘Weird Nature’ video titled ‘Relationships’