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Chapter 24 Mastering Biology

Terms in this set (22)

What is the most important factor that holds a gene pool of a species together and prevents speciation?
Gene flow
Two animals are considered members of different species if they _____.
cannot mate and produce viable, fertile offspring
What is genetic drift?
A change in allele frequencies caused by random events
Why are the large finches now living on the Galápagos Islands different from the original source population from a nearby island?
All three answers are correct.
True or false? The last ice age produced many different species mainly because populations dispersed and colonized new habitats.
False
Which of the following statements about reinforcement is true?
Reinforcement is a type of natural selection.
A subset of a population of birds leaves its habitat on the mainland and colonizes a nearby island. The birds, after a period of time, become reproductively isolated. The island sinks and the population of birds that lived on the island returns to its original habitat. Which of the following statements about these bird populations is true?
The populations will not be able to interbreed because they are different species.
A population of birds colonizes an area in which the insects upon which they feed live inside trees. Which of the following events accounts for an observed increase in average beak size in the bird population over time?
Increased fitness of large-beaked birds, leading to natural selection
True or false? A flood that separates a population of frogs onto opposite sides of a lake is an example of a vicariance event that may result in allopatric speciation.
True
Gametes from two plant species combine and produce a haploid zygote, and that zygote develops into a haploid, hybrid plant. Why is the hybrid plant sterile?
Meiosis cannot occur. and The cells do not contain homologous chromosomes.
The sequence of events illustrated in this figure results in a fertile hybrid plant called an allopolyploid. Which of the following statements is the most complete description of an allopolyploid?
It contains more than two sets of chromosomes, which are derived from two species.
Plant species F has a diploid number of 8. Plant species G has a diploid number of 10. What would be the diploid number of an allopolyploid hybrid of species F and species G?
18
What role does nondisjunction play in the formation of a fertile allopolyploid hybrid?
It doubles the chromosome number in the hybrid
Hybrid zones provide an opportunity to investigate _____.
the evolution of reproductive isolation
A certain species of salamander was split into two populations by a wide, dry valley, and the populations began to diverge from each other. After a period of time, some members of the two populations began to interbreed in a hybrid zone at the southern end of the valley. Only weak reproductive barriers existed by this time, so the two populations could freely interbreed and re-establish gene flow. This outcome in a hybrid zone is known as _____.
fusion
Based on these observations, do you think that the number of malaria cases will increase, decrease, or stay the same in the future?
The number of malaria cases will increase.
Feathers either play a role, or may have played a role, in _____.
All of these
_____ is rapid speciation under conditions in which there is little competition.
Adaptive radiation
Mass extinctions create conditions that promote _____.
Adaptive radiation
The appearance of an evolutionary novelty promotes _____.
Adaptive Radiation
The different finch species found on the Galápagos Islands probably arose as a result of _____.
Adaptive radiation
According to the _____ model, evolution occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods.
punctuated equilibrium
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