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UNIT 5

UNIT 5. The origin of life and evolution. HOW A SPECIES IS FORMED. Biology and Geology 4. Secondary Education. UNIT 7. UNIT 7. UNIT 7. UNIT 7. UNIT 7. UNIT 5. How a species is formed. 1. One or more groups of organisms from a population with the same genetic make-up become isolated.

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UNIT 5

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  1. UNIT5 The origin of life and evolution HOW A SPECIES IS FORMED Biology and Geology 4. Secondary Education

  2. UNIT7 UNIT7 UNIT7 UNIT7 UNIT7 UNIT5 How a species is formed 1. One or more groups of organisms from a population with the same genetic make-up become isolated A group of omnivorous birds, with thicker or thinner beaks, is isolated from the rest on an island which has lots of seeds (island A). Another group of omnivorous birds, with thicker or thinner beaks, is isolated from the same population on an island which has lots of insects (island B). Biology and Geology 4. Secondary Education

  3. UNIT7 UNIT7 UNIT7 UNIT7 UNIT7 UNIT5 How a species is formed 2. Over time, each group accumulates different genetic variations and natural selection acts on the populations of each group On island A, natural selection favours the genetic variations of birds with thicker beaks, which are better suited to breaking seeds. On island B, natural selection favours the genetic variations of birds with thinner beaks, which are better able to capture insects. Biology and Geology 4. Secondary Education

  4. UNIT7 UNIT7 UNIT7 UNIT7 UNIT7 UNIT5 How a species is formed 3. After a long time, the differences between the groups are so great that the two groups become different species In time, a species of birds with thick beaks arises on island A. The cross of one of these birds with one from island B will no longer produce fertile descendants. In time, a species of birds with thin beaks arises on island B. The cross of one of these birds with one from island A will no longer produce fertile descendants. Biology and Geology 4. Secondary Education

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