1. Mechanisms of Evolution
Study Guide Review

2. What effect should traits have on the fitness of an organism if the organism is to succeed?
It must increase fitness     

3. What factors determine how natural selection affects a population?
Favorable adaptations increase fitness, leading to increased allele frequencies through successful mating

4. Differences in the shape of tortoise shells, or the length of their necks on different Galapagos Islands would most likely be attributed to?  
adaptations to different environments such as feeding or habitat

5.   What attributes would help organisms survive under limitations, such as resources?
Adaptations that are suited to the environment in which the organism lives

6. Half of a large population being geographically isolated can lead to what change over time?
Reproductive isolation

7. An isolated population can be subject to what types of genetic issues?
a small gene pool, no change in the allele frequency over time, low genetic diversity
Ex> Polydactyly -- extra fingers or toes -- is one symptom of Ellis-van Creveld syndrome, commonly found among the Amish of Pennsylvania

8. What is an adaptation?  
A trait that allows an organism to survive and reproduce

9. What happens when a population is subjected to speciation?
New species arise

10. What is the struggle for existence?
more members of population are born than can survive and must compete for food, living space, and other necessities

11. What is artificial selection? How does it differ from natural selection?
Breeding of organisms
possessing desirable
characteristics; controlled by
man  

12. What are the conditions necessary for natural selection to occur?
more offspring are born than can survive, fitness varies among individuals, and there is heritable variation among members of the population.

13. What is the principle behind common descent?
organisms who share common
ancestors will share common
inherited characteristics

14. What is fitness? the ability of an organism to survive
and reproduce in its
specific environment

15. Which organisms thrive in a particular environment?
Those that are best
adapted to that
environment

16. A population decreases and a significant decrease in variation is observed in this population. This may be caused by_______________.  
a genetic bottleneck

17. In natural selection, individuals best adapted to their environment survive due to  
possession of inherited characteristics that increase fitness.

18. Charles Darwin’s theory of evolution by natural selection explains
Through evolution, species descend from common ancestors, and those with low fitness become extinct.

19. What effect on frequency of genes will those associated with traits beneficial to the survival of a species in a particular environment have?
they become more frequent

20. Organisms well suited to their environment not only survive, but also________.
reproduce

21. The evolution of weeds that are resistant to pesticides illustrates_________.
natural selection

22. According to the theory of evolution by natural selection, populations that thrive have what relationship with the environment?
They are best adapted to their environment.

23. Courtship dancing, mating calls, attractive plumage (feathers) in birds are all examples of what type of isolating mechanism?
Behavioral

24. A species of squirrel mating at a different time than another squirrel species would be an example of what type of isolating mechanism?  
temporal