The Origin of Species
Evolution in
Darwin’s Finches
Darwin’s Finches
Hybrid Zones
Showcases of Speciation
Reveiw
100
Describe how reproductive barriers arise:
-can evolve as populations diverge
-the environment of an isolated population may include different food sources, different types of pollinators, and different predators
100
Is it more likely for a cat or flower to experience polyploidy?
-Flower
100
Why was it important for the researchers to establish that beak morphology is heritable?
Natural selection can only modify heritable traits
100
Isolated islands are often showcases of speciation, how?
Repeated isolation, speciation, and recolonization events on isolated island chains have led to adaptive radiations of species, many of which are found nowhere else in the world.
100
According to the biological species concept, species are defined by their
particular roles in a biological community.
ability to interbreed and produce viable, fertile offspring.
reproductive isolation from nearby populations.
common ancestry.
ability to interbreed and produce viable, fertile offspring.
200
Females of the Galápagos finch respond to the songs of males from their island but ignore the songs of males from other islands. How would you interpret these findings?
Behavioral barriers to reproduction have begun to develop in these allopatric (geographically separated) finch populations.
200
The evolution of many diverse species from a common ancestor is known as adaptive radiation?
adaptive radiation
200
? are regions in which populations of different species meet and mate producing at least some hybrid offspring.
Hybrid zones
200
?, the process by which one species splits into two or more species, accounts for both the unity and diversity of life.
Speciation
200
Which of the following is an example of a postzygotic reproductive barrier?
One Ceanothus shrub lives on acid soil, another on alkaline soil.
Mallard and pintail ducks mate at different times of year.
Two species of leopard frogs have different mating calls.
Hybrid offspring of two species of jimsonweeds always die before reproducing.
Hybrid offspring of two species of jimsonweeds always die before reproducing.
300
Sympatric speciation occurs when?
a new species arises within the same geographic area as its parent species.
300
What leads to adaptive radiations of species?
Repeated isolation, speciation, and recolonization events on isolated island chains have led to adaptive radiations of species, many of which are found nowhere else in the world.
300
In ? hybrid zones, a limited number of hybrid offspring continue to be produced.
stable
300
? keep species separate. Such barriers isolate a species’ gene pool and prevent interbreeding.
Reproductive barriers
300
Biologists have found more than 500 species of fruit flies on the various Hawaiian Islands, all apparently descended from a single ancestor species. This example illustrates
polyploidy.
temporal isolation.
adaptive radiation.
sympatric speciation.
adaptive radiation.
400
Many plant species have evolved by (?), duplication of the chromosome number due to errors in cell division.
polyploidy
400
Explain why isolated island chains provide opportunities for adaptive radiations.
-new resources and an absence of predators
-natural selection, adaptation to its new habitat, and may evolve into a new species
400
Why might hybrid zones be called “natural laboratories” in which to study speciation?
By studying the fate of hybrids over time, scientists can directly observe factors that cause (or fail to cause) reproductive isolation.
400
List prezygotic barriers and postzygotic barriers:
400
What prevents horses and donkeys from hybridizing to form a new species?
limited hybrid fertility
limited hybrid viability
hybrid breakdown
gametic isolation
limited hybrid fertility
500
Habitat differentiation and sexual selection, usually involving mate choice, can lead to?
-sympatric (and allopatric) speciation.
500
Explain how adaptation has worked with these birds:
These birds resemble each other in many ways, but they differ in their feeding habits and their beaks, which are specialized for what they eat
-various foods include insects, large or small seeds, cactus fruits, and even eggs of other species
500
Sexual selection can lead to ?
speciation
500
Name the two types of speciation represented by this diagram. For each type, describe how reproductive barriers may develop between the new species
Allopatric speciation: Reproductive barriers - geographically separated populations
Sympatric speciation: Some changes, maybe in resource use or female mate choice, may lead to a reproductive barrier that isolates the gene pools of these two populations
500
Describe hybrid breakdown, is it a postzygotic or prezygotic barrier?
-viable or fertile hybrids with feeble or sterile offspring
-post