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Download 21.3 Interactions among living things pg 722
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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
