1. 7.1 Variation 7.2 Artificial Selection

2. 2 What causes VARIATION? Remember Genetics 3

3. 3 offspring have a combination of genetic material from both parents sexual reproduction (crossing over + independent assortment) = variation genetic variation in a population results from the variety of genetic information in all individuals of the population 3

4. 4 What Causes Variation?Mutations When the DNA is copied during INTERPHASE (you have about 175 mutations compared to your parents DNA) Mutations in gametic cells can be passed down and create change Mutagens: external factors that cause DNA to change Ex: Ultraviolet radiation 4

5. 5 Are variations good or bad? It depends.... Interaction with environments is what determines if a variation of a trait is advantageous or not. Variations can be advantageous / neutral / harmful 5

6. 6 Are variations good or bad? Variations within a population are GOOD - resistance to disease - resistance to other changes - allows for adaptations to develop

7. 7

8. 8 Peppered Moth If ALL the moths were the same then they would have ALL died. Variation allowed this species to survive. Depending on the ENVIRONMENT different VARIATIONS were “selected for”

9. 9 WHAT HAPPENED? –Pollution caused the lichen to die –Light peppered moths stood out –Light peppered moths were eaten –Dark moths survived and reproduced –When the conditions changed the opposite occurred Peppered Moth

10. 10 Selective Pressure Environmental conditions that select for certain characteristics and select against others –climate conditions –predators present –natural variations in habitat

11. 11 Artificial Selection Selective pressure exerted by humans on populations in order to “improve” or modify particular desirable traits Since the desirable traits are selected by humans it may not be an improvement to the species if left in nature

12. 12 Artificial Selection vs Natural Selection SELECTIVE pressure –Artificial: the selective pressure is HUMANS or conscious human caused conditions –Natural: the selective pressure is in NATURE –& Natural Selection is SITUATIONAL

13. 13 Artificial Selection Has been happening for a VERY long time –SELECTIVE BREEDING is another name for Artificial Selection

14. SELECTIVE BREEDING Doebley et al. In press. People select which organisms to breed. based on desirable TRAITS desired by humans This leads to a higher frequency of the desired traits

15. 15 Benefits of Artificial Selection in Food Crops Higher yield More desirable colour Nutritional value Drought - resistant Pest - resistant Grow quickly 15

16. 16 Artificial Selection in Animals

17. 17 Belgian Blue COW Cool Cows! http://www.youtube.com/watch?v=Nmkj5g q1cQUhttp://www.youtube.com/watch?v=Nmkj5g q1cQU 17

18. 18 Higher meat production Less fat production Higher milk production Grow faster Produce more eggs Resistant to disease 18 Benefits to Artificial Selection in Animal Agriculture

19. LINK TO DARWIN “The circumstances under which our domestic productions are reared are widely different... In conformity with this, all our domesticated productions, with the rarest exceptions, vary far more than natural species.” -Darwin (1896) Darwin took notes on the domestication of plants, farm animals and dogs. He bred pigeons himself. He used this as a springboard for his theory of Evolution by means of Natural Selection