Env. Science - Chapter 2.3 Notes

By the end of this lesson, we
will be able to…

◎ Explain the process of evolution by

natural selection

◎ Explain the concept of adaptation

◎ Explain the concept of coevolution

◎ Define the term extinction

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Organisms tend to be well-suited to
their natural environments

◎

A kangaroo rat is well suited to the deserts of

the southwestern United States and northern

Mexico, where there is little water

◎

One of the ways they cope with this dry

environment is by conserving the water in

their bodies

◉They eliminate very little water in their

urine or feces

◉They do not sweat

◉They are active at night when it is cooler

◉They never need to drink

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Natural Selection

◎

The unequal survival and reproduction

that results from the presence or

absence of particular traits

◎

Discovered by Charles Darwin

◎

Some individuals, because of certain

traits, are more likely to survive and

have offspring

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Evolution

A change in the genetic

characteristics of

populations from one

generation to the next

◎

Natural selection is

responsible for evolution

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Adaptation

An inherited trait that increases an organism's chance of survival

and reproduction in a certain environment

◎

Imagine a group of deer living in a lowland area where the

temperatures are warm most of the year. What if some of

those deer become separated from the others high in the

mountains, where the temperatures are colder most of the

year. Many of the deer would die in the cold but some might

have thicker fur and will survive and reproduce. The

offspring would have thicker fur and be likely to survive and

continue to reproduce

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Coevolution

When two or more species evolve

in response to each other

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EXTINCTIO

N

The irreversible disappearance of a population or

species

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