Basics 5.5 continued - Nat'l selection, formation of a new species

• Biologie
• Middelbare school
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• Leerjaar 3

Basics 5.5 continued

Today's plan

• HW review
• What is natural selection?
• How are new species formed?

What is evolution?

Which scientist first introduced the theory of evolution?

Q. 17: There are more people with dark skin and black hair closer to the equator. Explain why?

Natural selection

• The process through which populations of living organisms adapt and change.
• Not all individuals have an equal chance of survival
• Healthy and strong individuals have the greatest chance of staying alive and having offspring
• Ex. giraffe

Peppered moths

• Prior to 1800 these moths had a light pattern, dark pattern was very uncommon - collectors item
• During the industrial revolution (1820-1840), soot darkened tree trunks and killed off lichen
• Light moths eventually became rare and the dark moths multiplied quickly. Why/How?

askabiologist.asu.edu

Speciation - formation of a new species

Two ways of formation
1.  Variation within a species
      a. Variation - different genotypes and phenotypes
      b. Species can then respond to environmental variation
2. Isolation

     a. When one species becomes separated and isolated from each other

     b. example: river, mountains, ice, desert or a sea

     c. Over time organisms become more different and can no longer             reproduce

To Do

Read 5,5

Do all parts of Q 18