How would you describe a relationship between a tick and a dog? Why? Objectives: SWBAT distinguish between the different types of symbiotic relationships. SWBAT explain the importance of symbiotic relationships in population control. Do Now: How would you describe a relationship between a tick and a dog? Why? How would you describe a relationship between a human and a dog? Why? Agenda: Species Interactions Ecosystem Simulation Life’s Work: Read chapter 2 and study for quiz on Tuesday

How Do Species Interact? Symbiosis: interaction between 2 or more species Predation Competition Parasitism Mutualism Commensalism

Parasitism: when one species (parasite) feeds on part of another species (host) by living on or in it

Although parasites can harm their hosts, they can promote community biodiversity. Some parasites live inside host (micro-organisms, tapeworms) Some parasites live outside host (fleas, ticks, mistletoe, sea lampreys) Some have little contact with host (dump-nesting birds like cowbirds, some duck species)

when both species benefit Mutualism: when both species benefit

when one species benefits without harming or benefiting the other Commensalism: when one species benefits without harming or benefiting the other

when one species (predator) feeds off of another (prey) Predation: when one species (predator) feeds off of another (prey)

The predator and prey cycle, when graphed, is often called a “Sawtooth Curve.”

Why is predation important? Predators usually kill the sick, weak or aged. Genetic stock is improved because the weaker animals are killed first. The surviving prey get greater access to limited resources.

when two or more species compete for limited resources Competition: when two or more species compete for limited resources

Factors That Affect Competition Increasing Competition Anything that increases the population, because the more organisms there are, the scarcer the resources Examples: increased birth rates, decreased death rates, increased food supply Decreasing Competition Anything that decreases the population, because the fewer organisms there are, the greater the resources Examples: increased death rate (from temperature, drought, disease, predators, etc.)

Your Turn Watch the following video clips and classify the type of relationship between the species. http://www.pbs.org/wnet/nature/lessons/symbiotic-strategies/video-segments/1496/