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What leads to speciation?
How do you define a species?
Morphology - looks
Ecology - habitat
Why is the definition of a species so important?
It has a political and enviromental importance.
How does Speciation occur?
1. Selection favors something over time, turning a species slowly into a new species.
2. Offshoot species arise from original population.
What is the Biological Species Concept?
A biological species is a group of interbreeding natural populations that are reproductively isolated from other such groups.
Different species' cannot do what?
Produce fertile offspring together.
What does a prezygotic isolating mechanism do?
Prevent union of gametes (sperm + egg).
What does a postzygotic isolating mechanism mean?
Something goes wrong after gametes unite.
What are the prezygotic isolating mechanisms?
Temporal Isolation - Species mate at different times
What are the postzygotic isolating mechanisms?
Hybrid Inviability - they die early
What is a zygote?
The sperm + egg together.
The Biological Species Concept cannot be applied to...
Species that reproduce asexually
Extinct organisms (fossils) - don't know enough about them
Limited gene flow between populations - they have never come into contact to try to mate so we don't know
Why is the lecture important?
The pace of extinction is increasing due to human activities. We are changing faster than species can change to adapt.
What does speciation do?
Creates Reproductive Isolation - different species.
What is Microevolution?
H-W measuring gene & allele frequencies - same species.
Biology Exam 1 - 3rd Lecture