Population Interactions Section 5.2- How do different species live with each other?

An Organism’s Niche The unique role of a species within an ecosystem is its niche. A niche includes the physical home (habitat), the abiotic and biotic factors necessary for survival, and ALL of the species’ interactions with other organisms. Basically a niche is an organism’s pattern of use of its habitat.

Symbiotic Relationships SYMBIOSIS is the interaction between 2 or more different organisms living together in a close long-term relationship. Example= lichens (fungi and algae) Lichens are the pioneer species of primary succession.

What is a symbiotic relationship? Relationship that exists between organisms that live in a community Often occurs because niches overlap They result due to the sharing of natural resources

Five (5) Ways Species Interact Competition Predation Parasitism Mutualism Commensalism

1. COMPETITION Relationship in which different individuals or populations attempt to use the same limited resource Each individual has less access to the resource, therefore BOTH are harmed Occur both within (intracompetition) species and between species (intercompetition) Species A Species B

Example: fox and wolf compete for the rabbit

2. PREDATION One organism feeds on another by killing it The organism that is fed upon is called the “prey” Prey have developed mechanisms to help avoid or defend against predators (great sense of smell) Predators have developed mechanisms making them better hunters (camoflauge) One organism is harmed, the other benefits Prey Predator

Example: snake (predator) and frog (prey)

f) Herbivory Specialized form of predation Herbivores feed on plants Technically doesn’t kill the plant- it affects their growth and reproduction Plants have natural defenses- thorns, spines, chemicals

Predator- Prey Graph 1. Populations cycle between predators and prey. 2. If the number of prey decreases, the number of predators eventually decreases.

3. PARASITISM Relationship where an organism (A) lives in or on another organism (B) and feeds on that organism (B) The organism the parasite takes its nourishment from is called the “host” Somewhat like predators BUT they don’t kill their host, they just make the host sick Species A benefits, Species B is harmed Host (B) Parasite (A)

Examples: mistletoe and tick

4. MUTUALISM When one species depends upon another species for survival BOTH species benefit from the relationship Close relationship, sometimes neither species can exist without the other Often coevolution occurs.

Example: Humans and E.Coli & Ants and the Acacia Tree

5. COMMENSALISM Relationship where one species benefits and the other species is neither harmed nor benefits Example: robin’s (bird) nest in a tree Bird Tree

Video examples… Competition: Giraffe Battle | Africa – YouTube Parasitism: Body Invaders – YouTube Predation: Wolf Hunting Tactics – YouTube

Video examples… Monsters inside me https://www.youtube.com/watch?v=SU3SDrI0BTo&list=PLb-or5XGClNe_8DRaPFtd0hrMv0dP_tV-&index=14