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    My book gives this definition:
    Environmental factor that confers greater chances of survival to reproduction age on some members of the population

    Doesnt make sense at all
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    A selection pressure is a factor that has an impact on organisms, giving some an advantage in survival over others, as some are better adapted. It can be biotic (e.g. predation) or abiotic (e.g. temperature).
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    Some condition that decides which organisms are best suited to live. Say the environment gets colder, therefore those with thicker fur are best suited to live.
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    Selection pressure is basically an external pressure that an organism faces to be selected (i.e. to not die) and therefore continue to reproduce and spread its superior genes.

    So if the temperature (an abiotic factor) increases in the Arctic, the raised temperature acts as a selection pressure (it's an environmental pressure that will lead to selection of some organisms over others). In this case, rabbits with summer fur will survive whereas those that don't change their winter coat to a summer one won't.
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    (Original post by Biologyquestions)
    My book gives this definition:
    Environmental factor that confers greater chances of survival to reproduction age on some members of the population

    Doesnt make sense at all
    A selection pressure is a change in the environment that triggers natural selection and brings about variation in the species giving the organism an advantage in the changing environment.
 
 
 
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