Chapter 1 Populations & Communities Section 3 Interactions Among Living Things Notes 1-3

Adapting to Environment Natural Selection Process that changes an organism to better suit their environment Process that changes an organism to better suit their environment Those organisms with characteristics best suited for their environment will be successful Those organisms with characteristics best suited for their environment will be successful Those poorly suited for their environment are less likely to reproduce or survive Those poorly suited for their environment are less likely to reproduce or survive Over time poorly suited characteristics disappear from the population

Adapting to Environment Adaptations Behaviors and physical characteristics that allow the organism to be successful in the environment Behaviors and physical characteristics that allow the organism to be successful in the environment Every organism has some kind of adaptation Every organism has some kind of adaptationNiche The role the organism plays in its environment The role the organism plays in its environment Its job…how it lives Its job…how it lives Food, how it gets food, what other organisms use it for food

Interactions Among Organisms Competition The struggle between different organisms to survive in a habitat with limited resources The struggle between different organisms to survive in a habitat with limited resources There is a limited amount of food, water, and shelter There is a limited amount of food, water, and shelter Those organisms that survive find a way to reduce competition Those organisms that survive find a way to reduce competition Finding a way to all use the same area for food Using chemicals to get rid of competition

Interactions Among Organisms Predation One organism kills and eats another organism One organism kills and eats another organism Predator: Predator: Organism that does the killing Adapt to become faster, develop a poison or lure Prey: Prey: Organism that is killed Adapt to become by using camouflage, warning colors and mimicry (See page 34 & 35)

Interactions Among Organisms Predation and Population Size See graph on page 36 See graph on page 36 As the wolf population increases, the moose population decreases As the wolf population increases, the moose population decreases Wolf eats too many moose Then the wolf pop. decreases and the moose pop. increases again Then the wolf pop. decreases and the moose pop. increases again Wolf die off because there isn’t enough food and then the moose start to rebound

Symbiosis Close relationship between two species that benefits at least one of the species Mutualism Both species benefit Both species benefit Bacteria in your large intestine receive food and shelter and you get nutrients from food that the bacteria break down for you Bacteria in your large intestine receive food and shelter and you get nutrients from food that the bacteria break down for you

Symbiosis Commensalism One species benefits and the other isn’t helped or destroyed One species benefits and the other isn’t helped or destroyed Doesn’t happen often in nature Doesn’t happen often in nature Red tailed hawk interacting with the saquaro cactus Red tailed hawk interacting with the saquaro cactus Hawk has shelter but cactus isn’t affected

Symbiosis Parasitism One organism lives in or on another organism and harms it One organism lives in or on another organism and harms it Parasite: Parasite: Organism that benefits Usually small Host: Host: Organism that is harmed Usually bigger than parasite Leeches on your body Leeches on your body Won’t usually kill the host, because it won’t have food or shelter anymore Won’t usually kill the host, because it won’t have food or shelter anymore

Homework Key Terms Ch. 1 Due: Friday