1. Imagine this… A human chain formed by joining your left hand to your mother's right hand, & your mother links her left hand to her mother's right hand, & so on through your maternal ancestors in a straight line… A chimpanzee faces you & does the same thing with his or her mother, grandmother, & ancestors in a line paralleling your ancestral line, forming a chimpanzee chain…

2. The 2 lines will form a common line after about 280 miles. That’s about the distance from here to Baton Rouge, Louisiana! This represents the number of generations of humans & chimps it took to form a separate species from a common ancestor.

3. The most recent common ancestor of humans & chimps

4. Speciation What causes new species to be formed?

5. Wolf & dog… same species? What about great dane & chihuahua?

6. What makes a group of organisms a species? Species: a group of similar organisms that are capable of producing fertile offspring Donkeys & horses are capable of mating & producing offspring. However, they are still considered separate species, because mules are infertile. Horse + Donkey = Mule

7. Population A localized group of a species in a defined area – Population of sunflowers, population of elephants, etc.

8. Biodiversity The sum total of the genetically based variety of all organisms in the biosphere There are millions of identified species on Earth & more are discovered all the time!

9. How did so many different species evolve when life started as unicellular organisms?

10. Speciation The isolation of populations can lead to speciation. For example, let’s say we have a population of finches. Half of the finches fly many miles away & colonize an island. Now we have 2 different populations of the finch species, but they’re isolated from each other. The 2 populations do not interact anymore. This isolation could lead to the evolution of a new species of finch!

11. Speciation Isolated populations adapt to their own environments. – Natural selection will act on the 2 populations separately! Genetic differences between the 2 populations add up over several generations. IsolationGene Pool Changes

12. Reproductive Isolation Reproductive isolation MUST occur for speciation to take place. The 2 populations must no longer be able to produce fertile offspring (become reproductively isolated) in order to officially become different species.

13. Isolation Mechanisms There are 3 ways a population can become isolated, allowing for speciation. – Behavioral Isolation – Geographic Isolation – Temporal Isolation

14. Behavioral Isolation 2 populations of a species are capable of mating, but they do not because of differences in mating behavior. WesternEastern The Eastern & Western Meadowlarks do not mate, because they use different mating songs.

15. Geographic Isolation 2 populations of a species are separated by a geologic or geographic feature that keeps them from mating. These 2 populations of squirrels are separated by the Grand Canyon.

16. Temporal Isolation 2 populations do not mate at the same time of the year, day, etc. These toads do not mate in the wild, because the American Toad mates early in the summer, & the Fowler's Toad mates in late summer.

17. Are your toes normal or webbed? On your tables, there is a cup of beads. Some are red & some are blue. – Blue allele = webbed toes, red allele= normal. – Red is dominant. WITHOUT LOOKING, draw 2 beads. Raise your hand if you have 2 blue alleles. Raise your hand if you have 2 red alleles. Raise your hand if you are a heterozygote.

18. Answer the following question on a sheet of paper (share!): If an earthquake separated the population (in the spot that I showed you), what would happen over time? Describe how the 2 populations would differ.