1. CHAPTER 14 The Origin of Species
Modules 14.1 – 14.2

2. Evolution Underground
Evolution has generally been thought of as a very gradual process
However, examples of rapid evolution have been observed

3. One example of rapid evolution occurred among mosquitoes who migrated into the London underground
In less than 150 years, Culex pipiens evolved into a new mosquito species, Culex molestus
The origin of new species is called speciation

4. The isolated mosquitoes adapted to their new underground environment
They altered their prey, mating habits, and breeding patterns
Environmental barriers that isolate populations are just one of many mechanisms in the evolution of species

5. CONCEPTS OF SPECIES 14.1 What is a species?
Linnaeus used physical appearance to identify species when he developed the binomial system of naming organisms
This system established the basis for taxonomy

6. But appearance alone does not always define a species
Example: eastern and western meadowlarks
Figure 14.1A

7. Similarities between some species and variation within a species can make defining species difficult
Humans exhibit extreme physical diversity
Figure 14.1B

8. The biological species concept defines a species as
a population or group of populations whose members can interbreed and produce fertile offspring

9. A ring species may illustrate the process of speciation1
OREGON
POPULATION
Sierra Nevada 2
Yellow- blotched
Yellow- eyed
INLAND POPULATIONS
COASTAL POPULATIONS
Gap in ring
Large- blotched
Monterey 3
Figure 14.1C

10. Most organisms are classified based on observable phenotypes
The biological species concept is not applicable to fossils or asexual organisms
Most organisms are classified based on observable phenotypes
The morphological species concept
The genealogical species concept defines a species as a cluster of organisms representing a specific evolutionary lineage
The ecological species concept defines a species by its ecological role

11. 14.2 Reproductive barriers keep species separate
Prezygotic and postzygotic reproductive barriers prevent individuals of different species from interbreeding
Table 14.2

12. Courtship ritual in blue-footed boobies is an example of one kind of prezygotic barrier, behavioral isolation
Many plant species have flower structures that are adapted to specific pollinators
This is an example of mechanical isolation, another prezygotic barrier
Figure 14.2A, B

13. Hybrid sterility is one type of postzygotic barrier
A horse and a donkey may produce a hybrid offspring, a mule
Mules are sterile
Figure 14.2C