How Traits Change Over Time. Natural Selection vs. Artificial Selection

Transcription

1 How Traits Change Over Time Natural Selection vs. Artificial Selection

2 Charles Darwin ( ) Sailed around the world

3 What did Darwin observe? The diversity of living species was far greater than anyone had previously known. Each island had its own type of tortoises and birds that were clearly different from other islands Each species seemed to be adapted to the particular environment in each island.

4 Darwin s Conclusions Survival of the Fittest Organisms best adapted to their environments will be more likely to survive, reproduce, and pass their desirable traits on to offspring NATURAL SELECTION Nature selects for genes that allow organisms to survive and reproduce

5 How does Natural Selection work? Lots of offspring Lots of variation Thousands of frog eggs are laid in clumps in a fresh water pond. Each clump is laid by one female. Few will survive to adulthood. Variation is a change that makes a difference in the way an organism looks or acts, which might be helpful or harmful Survival of the fittest; Not everybody survives

6 Results of Natural Selection Organisms survive to pass on desirable traits. Over time, populations of organisms become better adapted to their environment by this process of natural selection.

7 EXAMPLE: This species of insect is well adapted (carries the right genes) to blend into its environment. This is an example of Mimicry. Do you see the walking stick insect? It received those genes from its parents, whose genes were successful enough to allow them to survive long enough to breed.

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11 Cats which are small and not aggressive Cows to produce more milk How has MAN changed the traits of organisms? Artificial Selection Dogs have been breed to be friendly Gold-colored fish Horses for speed

12 If you wished to breed the prettiest guppies, how would you do it? By only selecting the most colorful guppies and those with the longest tails, then breeding them generation after generation. Wild guppies Guppy which has been selectively bred.

13 Artificial Selection-Selective Breeding Selective Breeding: the process of breeding plants and animals for particular desirable traits. Also called Manmade selection Examples: Dog Breeding Breeding for high milk producing cows Breeding for food with desirable traits

14 Dog breeders have been selectively breeding for desirable traits for centuries.

15 Selective Breeding Nature provides variation, humans select variations of genes that are useful. Example - a farmer breeds only his best dairy cows

16 Farmers have cultivated many popular vegetables from wild mustard, by artificially selecting for certain attributes.

17 Hybrid Fruits Nectarcots Pluots Tangelo How many types of apples are there?

18 Artificial Selection-Genetic Engineering Genetic Engineering: Change the DNA of an organism directly by inserting DNA from one organism to another. Using genetic engineering you can make: New organisms Modified organism Examples: Glow in the dark cats Insulin producing bacteria Genetically modified foods

19 Insulin producing bacteria Insulin is a chemical humans need to process sugar. Diabetics need to take insulin. Human insulin gene is inserted by genetic engineering into the DNA of bacteria Bacteria produce the human insulin.

20 Tomatoes have been genetically modified to slow the ripening process to prevent softening and rotting, while allowing the tomato to retain its natural flavor and color.

21 Other examples Web Spinning Goats Vaccines in Bananas Pollution fighting plants Oil-spill cleaning bacteria Genetically Modified Trees to grow faster, yield better wood and even detect biological attacks. Genetically Modified Plants have been genetically engineered to resist herbicides, produce internal pesticides, or increase their protein production 12 bizarre examples of genetic engineering