Download Chapter 11 Section 3

Chapter 11 Section 3
Interactions Among Living Things
Adapting to the Environment
• Natural Selection – a characteristic that makes
an individual better suited for its environment
– Survival of the Fittest
• Adaptations – the results of natural selection
– The behaviors and physical traits that allow
organisms to live successfully in their
environments
Adapting to the Environment
• Niche – the role of an organism in its habitat,
or how it makes its living
– Type of food organism eats
– How it obtains its food
– When and how organism reproduces
– Physical conditions needed to survive
Interactions
• 3 Major Types
– Competition
– Predation
– Symbiosis
Competition
• Definition: the struggle between organisms to
survive as they attempt to use the same
limited resource
• If 2 species occupy the same niche, one of
them will eventually die off
Predation
• Definition: interaction where one organism
kills another organism for food
• Prey = species that is being killed
• Predator = species that is doing the killing
• Predation can have a major effect on
population size
• Populations of predators and their prey rise
and fall in cycles
• Predator Adaptations: Predators have
adaptations that help them catch and kill their
prey
• Prey Adaptations: Prey species have
adaptations that help them reduce the chance
of being caught and killed
Symbiosis
• Definition: a close relationship between 2
species that benefits at least 1 of them
• 3 Types of Symbiotic Relationships
– Mutualism
– Commensalism
– Parasitism
Mutualism
• Relationship where both species benefit is
called mutualism
– Example: long eared bats and saguaro
Commensalism
• Relationship where one species benefits and
the other species is neither helped nor
harmed.
• Example: Hawks and Saguaro
Parasitism
• One organism lives on or inside another
organism and harms it (but doesn’t usually kill
it)
• Parasite = organism that benefits
• Host = organism that is harmed
• Example = Tapeworms and dogs; Ticks and
dogs