Topic 3: Other Relationships with Ecosystems

Predator-Prey Relationships

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.

Predation: A Cyclical RelationshipPredation: A Cyclical Relationship

What is happening in this graph? 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.

Boom and Bust, Predator and Prey

Predation Avoidance

Predator/prey Predator/prey relationships are relationships are complexcomplex

Prey have various Prey have various defense defense mechanisms:mechanisms: CamouflageCamouflage MimicryMimicry

1. Camouflage1. Camouflage

Adaptation in Adaptation in form, shape or form, shape or behaviorbehavior Snowshoe hare Snowshoe hare

White in winterWhite in winter FrogsFrogs

Dark on topDark on top Light Light

underneathunderneath

Camouflage Hides Prey

When organism takes on coloring, shape, or When organism takes on coloring, shape, or behaviour that will provide it with an advantagebehaviour that will provide it with an advantage

2. Mimicry

Dronefly, a bee mimic, on Dandelion flower – note that the shape of the eyes, the number of wings (2 as opposed to 4) and a wide waist distinguishes it from the honeybee; but from a distance one is easily fooled.

Mimicry ..only one dangerous!!

Viceroy Butterfly

Monarch Butterfly

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

resources.

CompetitionInter-specific Competition:

between 2 members of different species

Intra-specific competition: 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

Ultimatein 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

Symbiosis: two or more species live in close contact

Three types: Mutualism Commensalism Parasitism

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. (+/0)

CommensalismCommensalismOrchid 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.

Intestinal Roundworm

ParasitismParasitism

Lymphatic Lymphatic FilariasisFilariasis (Elephantiasis) (Elephantiasis)

The disease is caused The disease is caused by by parasitic wormsparasitic worms, , including including Wuchereria Wuchereria bancroftibancrofti, , Brugia Brugia malayimalayi, and , and B. timoriB. timori, , all transmitted by all transmitted by mosquitoes. mosquitoes.

Bed Bugs - They do exist!