7.10: Speciation Flashcards
What is speciation?
A process by which new organisms form
When does speciation occur?
When populations are reproductively isolated from each other
What are the two types of isolation?
Allopatric and sympatric
What is a species?
A group of interbreeding organisms that exchange genetic information to produce viable, fertile offspring
What do prezygotic barriers do?
They prevent the production of a zygote
What are the five types of prezygotic barriers?
Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gamete isolation
Habitat isolation
2 species live in different habitats and don’t cross paths
Temporal isolation
2 species mate at different times of the year
Behavioral isolation
2 species have different courtship behaviors
Mechanical isolation
2 species that have reproductive differences and physically can’t mate
Gamete isolation
Sperm of one species cannot fertilize the egg of another species
What do postzygotic barriers do?
They prevent the zygote from developing into a viable, fertile offspring
What are the three types of postzygotic barriers?
Hybrid inviability, hybrid sterility, hybrid breakdown
Hybrid inviability
Incompatibility stopes the development of a zygote
Hybrid sterility
Hybrid offspring are vigorous but sterile
Hybrid breakdown
The first generation of hybris are viable and fertile, but subsequent generations are not
Allopatric speciation
Physical separation between two species due to geographic barriers
Sympatric speciation
No physical barrier
The separation between 2 two species due to reproductive isolation
What causes divergent evolution?
When adaptations to new habitats result in phenotypic diversification
What is punctuated equilibrium?
Evolution occurs rapidly after a long period of stasis (little to no change)
What is gradualism?
Evolution occurs slowly over long periods of time
What is an example of divergent evolution?
Darwin’s finches located on the Galapagos ISlands
What is adaptive radiation?
The evolution of a new species allows empty ecological roles/niches to be filled
