Exam3 Flashcards
What is heterostyly?
A genetic phenomena where two distinct phenotypes are maintained within a population and there are no intermediate phenotypes. The name comes from the fact that each mates with the “other style.”
What is the primary problem with creationism?
It isn’t falsifiable.
What are the mechanisms of evolution?
- ) Mutation
- ) Allele flow
- ) Selection
- ) Genetic drift
- ) Non-random mating
What is the fundamental argument of the origin of the species?
- ) All organisms produce more offspring than can possibly survive
- ) All organisms vary
What is macroevolution?
The origin or extinction of a new taxonomic group
- -Sometimes fast and sometimes slow
- -It has two processes: speciation and extinction
What are the two processes of macroevolution?
Speciation and extinction
Who developed the modern theory of speciation?
Ernst Mayr
How do new species come to exist?
Reproductive isolation. Said another way, the blocking of allele flow.
What does sympatric mean?
species living in the same place
What would happen to closely related species if there were no isolation mechanisms?
Allele flow would commence and they would turn into one polymorphic species.
Without some isolation mechanism alleles would flow through sympatric species. What would happen?
Species would never have evolved because it would be impossible to create new species because alleles would be constantly flowing back and forth.
What are the two categories of isolation mechanism?
Prezygotic–prevents mating so that no gametes are formed. Postzygotic-prevents fertilazation after mating has occurred
What are the mechanism of postzygotic isolation?
- -Habitat isolation
- -Temporal isolation
- -behavioral isolation
- -mechanical isolation
- -gametes dies
Name an example of habitat isolation?
Sympatric species of toad foot seldom meet because they prefer different soil types.
Some species of bird lice never meet because they mate of different hosts.
Name an example of temporal isolation?
The American toad and the Flower Toad mate in the lab, but mating doesn’t occur in the wild because they mate a different times of year.
Name an example of behavioral isolation?
Morphologically identical lacewings do not interbreed because their songs are different.
Gulls normally mate with their own species, but since they are highly visual animals, if, at birth, they imprint on a closely related gull species, they will mate with the related species.
How does one prove the existence of an isolation mechanism?
By artificially removing it to see who mates. If two species that don’t typically mate, mate after the barrier is removed, then you researched has confirmed the mechanism of isolation.
What is Hurt and Hendricks experiment?
They found that topminows from the amazon, which have been isolated for 2 million years will hybridize than not mate when not given the option to mate with their own species.
But hybrid fitness was lower, especially when these hybrids crossed with original species. This hybrid breakdown is a form of post zygotic isolation.
Are Hurt and Hendrick’s topminnows separate species?
It is subjective. If the populations mixed the process of reinforcement would probably complete the job and they would be conclusively separate species. So, probably, yes.
What is REINFORCEMENT?
It is a mechanism by which incipient separating species confirm their separation. Because of lower hybrid fitness, any trait that causes females not to male with the other species becomes common and the species finally separate. It doesn’t happen in males because a few unit offspring doesn’t have the same impact.
Name an example reinforcement?
Coyne and Orr documented two species of drosphila where the females have be selected by a reinforcement mechanism.
When the species are captured in a an area where they overlap, the two species do not mate with each other. Clearly a reinforcement mechanism has been selected for.
When the two species from an area where they have been unexposed each other are captured, they mate show that no reinforcement mechanism has been selected for.
What is a host shift? Name an example?
Many parasites mate on hosts. When they choose a new host they become reproductively isolated.
Apple maggots are a famous example. When apple trees were introduced to the United States, Hawthorn maggots began feeding on them. Now apple maggots and hawthorn maggots are reproductively isolated.
What is parapatry?
Speciation is not clear cut. Some populations interbreed, others do not. This is called PARAPATRY.
For example, the CA garter snake. Each population of garter snake is able to breed with the population closest to it but not with the populations further away.
What is systematics?
The study of phylogeny
