Community Interactions Objective: A3 - Interpret relationships, including predation, parasitism, commensalism, mutualism, & competition among organisms. - such as, competition, predation, and symbiosis can powerfully affect an ecosystem

Every morning in Africa

A gazelle wakes up & “knows”

It must run faster that the fastest lion                                                                    

Or it will be killed.                                               

Every morning, a lion wakes up & “knows”

It must outrun the slowest gazelle

Or it will starve to death

It doesn’t matter whether you are a lion or a gazelle

When the sun comes up,

                                                                         You better be running …

Competition: Occurs when organisms of the same or different species attempt to use an ecological resource in the same place at the same time

Things that reduce competition. - being active at different times of Things that reduce competition - being active at different times of the day - establishing territories - establishing hierarchies - requiring different resources at different times of the life cycle

Hunter & hunted Predator - prey Predation: Hunter & hunted Predator - prey

Predator and Prey Adaptations

- Camouflage (cryptic coloration)

- Warning coloration Poison frog, coral snake Marked with bright or contrasting colors as a warning that the animal is venomous or noxious.

- Distasteful

- Hooves for running fast - Horns for protection - Hooves for running fast

- Deceptive markings (eyespots)

- Sharp Hearing

- Mimicry Example: Monarch & Viceroy

- Sting - Poisonous

- Offensive Odors / Repellant Chemicals

- Ability to run fast

- Sharp horns - Sharp tearing teeth

- Claws for piercing

Lynx & hare

Predator – prey graph

Some unusual relationships:

Symbiosis: Mutualism   – both species benefit from the relationship

Rhino & Oxpecker the oxpecker is a bird that rides around on the backs of cattle and other large animals such as rhinos.  The oxpecker feeds on ectoparasites of the cattle such as ticks and warns the animals of approaching predators; thus both organisms benefit in a loose mutualism.  On the other hand, the oxpeckers also pick at scabs and wounds on the animals and may ingest bits of flesh and blood (thus making them more like parasites).  The natural world is complicated!

Lichen = alga & fungus The example below is a lichen growing on the trunk of a mangrove tree. The lichen consists of a fungus and an algae growing together. The fungus gets food from the photosynthesising algae and the algae gets a place to live.

Rhizobium (nitrogen fixing bacteria) & legume nodules Rhizobium bacteria change nitrogen into a usable form for plants. These plants provide shelter for the Rhizobium as nodules on the roots of legumes, such as beans and peas.

E. coli & human gut E. coli is a comman rod-shaped intestinal bacterium. It lives in a mutualistic relationship with humans where it benefits from the warmth, shelter, and nutrients provided by the colon and in return makes vitamin K and sodium. It also serves as a competitive inhibitor of pathogenic bacteria. E. coli does not cause disease or discomfort but does produce 400ml to 500ml of gas per day. Prolonged treatment with antibiotics may reduce the population of E. coli within the intestines.

Commensalism  – one organism benefits and the other is neither helped nor harmed (a one-way relationship)

Clownfish & Sea Anemones The clownfish benefits by having a protected home territory. (Clownfish are small, brightly-colored fish found in coral reefs. They are frequently found in the tentacles of sea anemones, which typically capture their prey by paralyzing them with discharged cnidoblasts (nematocysts) , and then ingesting the animal within the gastrovascular cavity. Studies have shown that a component of clownfish mucus inhibits the discharge of these cnidoblasts.)

Shark & Remora                                                         Shark remora's are the most common remora in warm waters. There are nine species of remoras. They can be found inshore as well as offshore. Remoras attaches to its hosts including sharks, rays, large fish, sea turtles, whales, dolphins and also to ships. Remoras feeds on small fishes, or scraps of fish that they eat when their host eats. The sucker on the remoras head is actually a modified dorsal fin.

Spanish moss growing on trees Spanish moss is considered an epiphyte-meaning it requires the host (pine tree in this case) for mechanical support rather than a source of nutrients or water.

Parasitism   – one organism benefits and the other is harmed

Endoparasites found in the intestine of dogs Tapeworms

Caterpillar & wasp larvae Ectoparasites the caterpillar had been parasitized long before we found it, probably by a braconid wasp. The mother wasp had laid eggs under the caterpillar’s skin, and the parasitic larvae had been munching on its guts ever since. Now they were all grown up and ready to pupate. Some species of parasitic wasp pupate inside of their host and spare you the whole Alien-like experience. Unfortunately, this was one of the species that burst out of the caterpillar’s skin before they spin coccoons. Caterpillar & wasp larvae

Mosquito

Leeches

Ticks & mammals