Defining Species
The most commonly used species definition in biology.
What is the biological species concept?
Barriers that prevent mating or fertilization.
What are prezygotic barriers?
Speciation caused by geographic isolation.
What is allopatric speciation?
A hybrid that cannot survive.
What is reduced hybrid viability?
Natural selection that increases reproductive isolation.
What is reinforcement?
Species are defined as groups that can do this.
What is interbreed and produce viable, fertile offspring?
Barriers that occur after fertilization.
What are postzygotic barriers?
Speciation without geographic isolation.
What is sympatric speciation?
A hybrid that survives but is infertile.
What is reduced hybrid fertility?
Fusion occurs when this happens between populations.
What is gene flow?
This species concept applies to asexual organisms.
What is the morphological or phylogenetic species concept?
Different mating seasons prevent reproduction.
What is temporal isolation?
A common cause of sympatric speciation in plants.
What is polyploidy?
Hybrid offspring that are viable and fertile.
What is hybrid vigor?
The gradual divergence of populations into separate species.
What is speciation?
This species concept focuses on evolutionary history.
What is the phylogenetic species concept?
Incompatible reproductive organs prevent mating.
What is mechanical isolation?
Speciation that occurs when a small population is isolated at the edge of a larger population.
What is peripatric speciation?
Hybrid offspring that are fertile initially but weak in later generations.
What is hybrid breakdown?
Two species that coexist in the same area.
What is sympatric species?
The biological species concept cannot be applied to this.
What are fossils or asexual organisms?
Reduced hybrid fitness is an example of this.
What is postzygotic isolation?
This occurs when a physical barrier splits a population.
What is vicariance?
Reinforcement leads to this outcome.
What is increased reproductive isolation?
The evolutionary process that leads to the diversity of life.
What is evolution?