This document provides information about speciation and the process of new species forming. It defines key terms like species, speciation, geographic isolation, reproductive isolation, and homologous structures. It explains that speciation occurs when two populations become separated and evolve traits over time that prevent interbreeding, forming new species. Random mutations provide variation and natural selection can make helpful mutations more common between isolated groups.

1. Assign Yourself: Finish Speciation Rally
Coach
• Do Now:
• Review of Evidence of Common Ancestry

3. Speciation

4. What is a species?
• A group of organisms that can interbreed (have kids
with each other) and produce fertile offspring (kids
that can also have kids).

6. Processing Piece
• Write “species” and draw a picture to help yourself
remember the definition.

7. What is speciation?
• The formation of new species.

8. Processing Piece
• Write “speciation” and draw a picture to help
yourself remember the definition.
• Make sure to show that both new species
originated from a “common ancestor.”

9. How does speciation happen?
1) New traits arise from random mutations.
2) Two populations of the same species are separated
from each other.
3) Natural selection causes the two populations to
change over time.
4) After many generations, the populations become
so different that they can no longer interbreed to
produce fertile offspring (kids). When this
happens, they are called different species.

10. Where does variation come from?
• New traits (like longer necks, different color eyes,
etc) arise from random mutations in the DNA.
• Usually, mutations are harmful. But sometimes
mutations are helpful, and natural selection makes
these helpful mutations more common.

11. Processing Piece
• Draw a picture to illustrate where new mutations
arise from.

12. What are 2 ways populations can be separated?
1) Geographic isolation = when they live in different
places
2) Reproductive isolation = when they are prevented
from interbreeding (making babies) with each other.
Example: if they have different mating seasons, or if they have different
mating rituals, they are “reproductively isolated.”

14. Processing Piece
• Write “geographic isolation” and “reproductive
isolation” and draw a picture to illustrate each one.

15. What is gene flow?
• When new genes go into or out of a population,
because individuals carrying those genes leave the
population, or immigrate into the population.
• Example: Two populations of lizards live on 2 different islands. For
many years, they evolve separately. Then, humans transport some
lizards from one island to another.

16. Processing Piece
• Write “gene flow” and draw a picture to help
yourself remember the definition.

17. What’s the difference between natural and artificial selection?
• Natural selection = nature determines which trait will make
an individual more likely to survive and reproduce
• Artificial selection = humans determine which trait will
make an individual more likely to survive and reproduce
• Example: In domesticated dogs, humans have chosen
which ones are allowed to breed, based on whether or not
they have certain traits.

18. Processing Piece
• Write “artificial selection” and “humans choose
traits.” Then draw a picture to help yourself
remember the definition of artificial selection.

19. What does it mean if 2 modern day organisms have
homologous structures?
• Sharing homologous structures means that they
share a common ancestor, NOT that one of them
evolved from another.
• Example: Wolves and dogs share many homologous structures. This
means that they most likely share a common ancestor, NOT that one
of them evolved from the other.

21. Exit Ticket
1) In order for a group of organisms to be considered
the same species, what do they need to be able to
do?
2) What is speciation?
3) True or false: if two species share homologous
structures, this means that one species evolved
from the other.