Chapter Fourteen: The Origin of Species

Questions:

1. How is gene flow between populations prevented and reduced?
2. Who is Charles Darwin?

Answers:

1. Gene flow is initially prevented by a geographic barrier such as a mountain or river.  It can be reduced by polyploidy, habitat differentiation, or sexual selection.x
2. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.

Key Terms:
Species- a group of organisms whose members can breed and produce fertile offspring, but who donot produce fertile offspring with members of other groups.
Speciation- the emergence of a new species.
Taxonomy- the branch of biology that names and classifies species and groups them into broader categories. 
Reproductive Barriers- isolate a species gene pool and prevent inbreeding.
Polyploidy- the multiplication of the chromosome number due to errors in cell division.
Hybrid Zones- where members of different species meet and mate to produce hybrid offspring.
Adaptive Radiation-when many diverse species evolve from a common ancestor.
Sympatric Speciation- when a new species may arise within the same geometric area as a parent species.
Allopatric Speciation- when populations of the same species are geographically separated, separating their gene pools.
Prezygotic Barriers- prevent mating and fertilization between species.

Key Facts:   
1. The biological species concept defines a species as a population or group of populations whose members have the potential to interbreed in nature and produce fertile offspring.
2. The morphological species concept classifies organisms based on observable phenotypic traits.  It can be applied to asexual organisms, fossils, and in cases when we donít know about possible interbreeding.
3. The ecological species concept defines a species by its ecological role or niche.  The morphological species concept classifies organisms based on observable phenotypic traits.
4. The phylogenetic species concept defines a species as a set of organisms representing a specific evolutionary lineage. 
5. The process of speciation depends on whether reproductive barriers prevent gene flow between populations.

Diagram:

Relevant Video:
http://www.youtube.com/watch?v=LEGQu3cm3CE 


Summary: