Lesson 8.2 Species Interactions The zebra mussel has completely displaced 20 native mussel species in Lake St. Clair.

Objectives Explain the difference between niche and habitat. Give examples of parts of a niche. Describe the five major types of interactions between species. Explain the difference between parasitism and predation. Explain how symbiotic relationships may evolve.

Lesson 5.2 Species Interactions The Niche Describes an organism’s use of resources and functional role in a community. A niche is different from a habitat. An organism’s habitat is a location. However, a niche is an organism’s pattern of use of its habitat. Often restricted by competition

Ways in Which Species Interact Interactions between species are categorized at the level where one population interacts with another. The five major types of species interactions are: Competition Predation Parasitism Mutualism Commensalism

Lesson 5.2 Species Interactions Competition Organisms compete when they seek the same limited resource. In rare cases, one species can entirely exclude another from using resources. To reduce competition, species often partition resources, which can lead to character displacement. Intraspecific Competition: among members of same species Interspecific Competition: among members of two or more different species

4 Types of Competition Competitive Exclusion Direct competition between species resulting in a winner and loser One species is very effective competitor by excluding another species from resources entirely Occurs when two or more species try to occupy the same exact niche

Fundamental and Realized Niche Full niche of species Realized Niche restricted by competition

Resource Partitioning Species partition, or divide, the resources they use in common by specializing in different ways

Character Displacement When resource partitioning can lead to the evolution of physical characteristics among the competing species that reflect their specialized role in the environment.

Lesson 5.2 Species Interactions Predation (+/–) The process by which a predator hunts, kills, and consumes prey Defensive traits such as camouflage, mimicry, and warning coloration have evolved in response to predator-prey interactions. Some predator-prey relationships are examples of coevolution, the process by which two species evolve in response to changes in each other. Rough-Skinned Newt Did You Know? A single rough-skinned newt contains enough poison to kill 100 people. Unfortunately for the newt, its predator, the common garter snake, has coevolved resistance to the toxin.

Predators and Prey All organisms need food and consumers must eat other organism to get it. Predators Consumers that actively hunt other organisms Prey Organisms upon which the predators feed on

Predator vs Prey Size of predator and prey populations are closely linked Large prey population=more predators Small prey population=less predators Population Cycles Time it takes for a population to rise and fall Some take 10 years, some 4 years Lifespan of organisms plays a role

Parasitism A relationship in which one organism feeds on the tissues or body fluids of another. Examples: Ticks, Fleas, lice, variety of worms Host Organism in which the parasite feeds True parasite Adapted to live on or in the host

Parasitism Cont. Population size is related to size of host Thrive in crowded host populations Density-dependent limiting factor because parasite is more successful in a dense host population

Symbiosis Relationship where two species live together closely Parasitism is a form of symbiosis One organism is harmed while one benefits Commensalism Relationship that benefits one species and neither helps or harms the other Barnacles on a whale

Symbiosis Cont. Mutualism Relationship where both species benefit Ants and Acacia Tree Flowers and Insects A remarkable 3-way mutualism appears to have evolved between an ant, a butterfly caterpillar, and an acacia in the American southwest. The caterpillars have nectar organs which the ants drink from, and the acacia tolerates the feeding caterpillars. The ants appear to provide some protection for both plant and caterpillar.

Videos Predator Vs Prey Video Parasitism Symbiotic Relationships http://www.youtube.com/watch?v=pVX49KhH0mc Parasitism http://www.youtube.com/watch?v=EWB_COSUXMw Symbiotic Relationships http://www.youtube.com/watch?v=pMN1zI2Dm4c

8.2 Quiz 1. Explain how competition can affect an organism’s niche. 3. The human digestive tract is filled with bacteria. The bacteria live in the body and get nutrients while helping to digest food. What kind of species interaction is this-mutualism or commensalism? Is it symbiotic? Explain 4. Copy the chart below and place a (+) or (-) to indicate the species interaction. Interaction Effect on Species A Effect on Species B Commensalism Competition Herbivory Mutualism Parasitism Predation