Relationships Within Populations

Tuberculosis bacteria feeding on human lung tissue Predation: a predator eats a prey.

Predator-Prey relationships are cyclical. When the prey’s population rises, there is more food for the predator so immediately their population goes up. When there is too many predators eating the prey, the population of prey drops… now there isn’t enough food for the predators so their population drops… and so on. Predation: A Cyclical Relationship

Boom and Bust, Predator and Prey

Predation Avoidance Predator/prey relationships are complex Predator/prey relationships are complex Prey have various defense mechanisms: Prey have various defense mechanisms: Camouflage Camouflage Mimicry Mimicry

Camouflage Adaptation in form, shape or behavior Adaptation in form, shape or behavior Snowshoe hare Snowshoe hare White in winter White in winter Frogs Frogs Dark on top Dark on top Light underneath Light underneath

Snowshoe Hare

Leaf bugs! Look like parts of the tree!!

organism will take on coloring, shape, or behaviour that will provide it with an advantage organism will take on coloring, shape, or behaviour that will provide it with an advantage Only one of the butterflies to the left are dangerous… but predators will stay away from all of them because they are hard to distinguish between Only one of the butterflies to the left are dangerous… but predators will stay away from all of them because they are hard to distinguish between Mimicry

Mimicry..only one dangerous!!

Competition: an interaction in which two or more organisms battle for the same resources.

Competition Inter-specific Competition: Inter-specific Competition: between 2 members of different species between 2 members of different species Intra-specific competition: Intra-specific competition: between 2 members of same species between 2 members of same species Competition can be for food, space, mates, oxygen, water

Barnacle Competition Intraspecific competition Interspecific competition

Gause’s Principle No 2 species can occupy same ecological niche Ultimate in inter-specific competition Species 1 Species 2 Competition leads to exclusion Paramecium

The competitive exclusion principle (aka Gause’s Law) States that two species that compete for the exact same resources cannot stably coexist. One of the two competitors will always have an ever so slight advantage over the other that leads to extinction of the second competitor in the long run.

Symbiosis: two or more species live in close contact. Three Types: Symbiosis MutualismCommensalismParasitism

Mutualism: a symbiotic relationship in which both species benefit Bali Island, Indonesia. A cleaner shrimp cleaning parasites from a moray eel's mouth

An example of mutual symbiosis is the relationship between clownfish that dwell among the tentacles of tropical sea anemones. The territorial fish protects the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protect the clownfish from its predators (a special mucus on the clownfish protects it from the stinging tentacles).

Commensalism: a symbiotic relationship in which one organism benefits, and the other organism is neither helped nor harmed.

Commensalism Orchid on tree

Parasitism: a symbiotic relationship in which on one organisms benefits, while the other is harmed. Tapeworm: Humans occasionally become infected by ingesting cereals contaminated with insect pests (intermediate hosts of this parasite). Symptoms include abdominal pain, diarrhea and headache.

Cowbirds engage in “brood parasitism” -- but in some cases this actually benefits their victims and it becomes mutualism!

) Lymphatic Filariasis (Elephantiasis) The disease is caused by parasitic worms, including Wuchereria bancrofti, Brugia malayi, and B. timori, all transmitted by mosquitoes.

Bed Bugs - They do exist! They are Parasites!!!