Download 21.3 Interactions among living things pg 722

21.3 Interactions among living things pg 722
• Key concepts: How do an organism’s
adaptations help it to survive?
• What are the major ways in which
organisms in an ecosystem interact?
• What are the three types of symbiotic
relationships?
• Key terms: natural selection,
adaptations, niche, competition,
predation, predator, prey, symbiosis,
mutualism, commensalism,
parasitism, parasite, host
Adapting to the environment
• Natural Selection – a process that selects individuals better suited to
their environments to reproduce. It results in adaptations.
• Adaptations – the behaviors and physical characteristics that allow
organisms to live successfully in their environments.
• Individuals who are poorly suited to the environment are less likely to
survive and reproduce.
Niche
• Every organism has a variety of
adaptations that are suited to its
specific living conditions.
• The role of an organism in its
habitat is its niche.
• Includes type of food, how it gets
food, which others use the same
food
• Also includes how and when the
organism reproduces and the
physical conditions it needs to
survive
Competition
• There are three major types
of interactions among
organisms: competition,
predation, and symbiosis
• Competition is the struggle
between organisms to
survive as they attempt to
use the same limited
resource (food, water,
shelter)
Predation
• An interaction in which one organism kills another for food.
• Predator – does the killing
• Prey – gets killed
• Effect of predation on population size: if there are many predators, a decrease in prey
population will occur. When that happens, the predators will die from lack of food.
Predator adaptations
• Speed, poisons, bigger eyes
Prey adaptations
• Speed, defensive mechanisms (smelliness, ability to puff up or
pretend to be bigger, pretending to be a different species, etc)
• Mimicry
• False coloring
• Camouflage
• Protective covering
Symbiosis
• Symbiosis is a close relationship
between two species that benefits
at least one of the species
• Three types occur: mutualism,
commensalism, parasitism
Mutualism
• Both species benefit
• E.g. saguaro cactus and longeared bats
• Bats get food and cactus gets
pollen transfer
Commensalism
• One species benefits and the other is not helped nor harmed
• Red tailed hawk with saguaro cactus
• Hawk gets a nest, cactus not affected
Parasitism
• One organism living on or inside
another and harming it.
• Organism that benefits is a parasite
• Organism that is used is a host
• Common parasites are ticks, fleas,
leeches
Please complete
• Page 729 section 3 assessment
• 1abc, 2abc, 3abc