Chapter 22 Flashcards
what two things must be accounted to make up a species?
the distinctness at a single location
and
connections between different populations in the same species
What is it called when species diverge in phenotypic and genetic traits within the same population?
Sympatric speciation
What is an intervening population?
A population that has the traits of other populations in a different area within the same species.
What are the pre-zygotic reproductive isolations?
Ecological isolation, behavioral isolation, temporal isolation, mechanical isolation, prevention of gamete fusion
What are the post-zygotic reproductive isolations?
Hybrid inviability and hybrid infertility
What is are the characteristics of a species according to the biological species concept?
The population has the possibility of interbreeding and must be reproductively isolated from other populations
What is are the characteristics of a species according to the ecological species concept?
When the gene flow is weak, a species’ differences are stabilized through natural selection (process is called reinforcement)
Can incomplete speciation and partial isolating reproduction exist?
Yes, some populations do not fully speciate, and some hybrids may be able to survive.
What is pre-mating isolation?
When circumstances do not allow two populations to breed
Ex: Some butterflies only pollinate one color of flowers while other butterflies pollinate another color of the same flowers. Those two colors of flowers will not get a chance to breed together.
Will reinforcement ensure complete speciation?
No, incomplete speciation may reverse back if the two populations meet again.
What other events would lead to speciation?
genetic drift (bottleneck effect and founders effect) and adaptation to different environments
Isolating mechanisms exist only to speciate populations. (True/False)
False, this is only true in reinforcement.
What are the two steps of speciation?
- Species must diverge
- Diverged species must form a reproductive barrier to maintain differences
What type of speciation takes place when two populations are geographically isolated?
Allopatric speciation
What type of speciation takes place when two populations are not geographically isolated, but still speciated?
Sympatric speciation
What are the two types of sympatric speciation?
Polyploidy and disruptive selection
Polyploidy is the instantaneous process in which an offspring has more than two sets of chromosomes either through autopolyploidy or allopolyploidy. (True/False)
True
What is autopolyploidy?
When an offspring gets more than two sets of chromosomes from one parent.
What is allopolyploidy?
When an offspring gets more that two sets of chromosomes from both parents, and extra chromosomes double.
What is the term for when an organism has four sets of chromosomes.
Tetraploid
What is the term for when an organism has three sets of chromosomes.
Triploid
Which is usually fertile, tetraploid or triploid?
Tetraploid, they have an equal amount of sets for meiosis to occur properly.
Disruptive selection is the generational process in which a population develops reproductive barriers and different phenotypes without diverging geographically with disruptions. (True/False)
True
What are the two types of duration theories in evolution?
gradualism and punctuated equilibrium
What is gradualism?
Small changes accumulated over millions of years that lead to a major difference between two species
What is punctuated equilibrium?
When a population does not change at all (stasis), but changes immediately within a short period of time (punctuated)
Why would a population be in stasis?
- The environment does not change at all (stabilizes) or the environment switches back and forth with different conditions (oscillates).
- The population moves toward a similar environment they were once in.
Does a population experience either only gradualism or only punctuated equilibrium?
No, a population can experience both in their evolution
