Speciation: How New Species Form
From One Population to Two
Speciation
Speciation is the process by which one lineage splits into two or more distinct species. It usually involves reduced gene flow and the buildup of reproductive barriers.
Reproductive isolation
Reproductive barriers can prevent mating, prevent fertilization, or reduce the survival or fertility of offspring.
Types of isolation
Prezygotic barriers
- Prevent mating or fertilization
- Examples include behavior, timing, and physical incompatibility
Postzygotic barriers
- Act after fertilization
- Examples include sterile or weak offspring
A simple path to speciation
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1
A population becomes separated or diverges.
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2
Different environments or chance events change allele frequencies.
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3
Reproductive barriers accumulate.
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4
The populations no longer exchange genes effectively.
What is speciation?
Speciation is the formation of new species.
Correct answer: One species splitting into two or more species
What is reproductive isolation?
Reproductive isolation reduces or stops gene flow between populations.
Correct answer: When populations can no longer successfully interbreed and produce fertile offspring.
Which is a prezygotic barrier?
Different mating seasons can prevent fertilization before a zygote forms.
Correct answer: Different mating seasons