1. The Evolution of a Species

2. How does a species evolve?
-The evolution of a new species is called speciation.
-A species are organisms that look alike and can have children with each other.
-Speciation happens when organisms in a population can no longer mate with each other to produce fertile offspring (children).
-Fertile means to be able to have children.

3. How does speciation happen?
1. Geographic isolation-a physical barrier divides a population. The separated members of the population can no longer breed and over time, develop different genes and become different species.

4. How does speciation happen?
Reproductive Isolation-species cannot mate with each other due to differences in DNA, different mating seasons or different # of chromosomes. Polyploidy is when the # of chromosomes doubled.

5. Geographic or Reproductive Isolation?

6. Geographic isolation

7. How much time does it take to develop a new species?
-Speciation takes a long time. There are 2 theories of speciation.
1. Gradualism-the idea that species develop slowly over a long period of time.
2. Punctuated Equilibrium-the idea that species don’t change over a long period of time, and then there is rapid change in a species

8. Gradualism or Punctuated Equilibrium?
Camel Evolution
Paleocene
65 million
years ago
Eocene
54 million
years ago
Oligocene
33 million
years ago
Miocene
23 million
years ago
Age
Present
Organism
Skull and
teeth
Limb
bones

9. Gradualism

10. Gradualism or Punctuated Equilibrium?
Loxodonta
africana
Elephas
maximus 1 2
Millions of Years Ago
Mammuthus
primigenius
Elephas 3
Loxodonta 4
Mammuthus 5
Primelephas 6
Ancestral species
about 55 million years ago

11. Punctuated Equilibrium

12. Patterns of Evolution
Convergent evolution-species evolve to look alike. Ex: Dolphins and sharks.
Divergent evolution-one species turns into many species. Ex: one bird to many birds.

13. Convergent or Divergent Evolution?

14. Divergent Evolution