SPECIATION

A population of 30 fish becomes isolated in a small pond. Over generations, several alleles disappear entirely, even though they were not harmful. What effect of genetic drift does this illustrate?

• Increased mutation rate

• Increase in gene flow

• Loss of genetic variation

• Strong natural selection

The process of a new species arising within the geographic range of the parent population is called

• ecological speciation

• allopatric speciation

• adaptive radiation

• sympatric speciation

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Which of the following must occur after a period of geographic isolation in order for the two sibling species to remain genetically distinct following their geographic reunion in the same home range?

• Prezygotic barriers

• Postzygotic barriers

• Ecological isolation

• Reproductive isolation

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Which of the following best illustrates the bottleneck effect?

• A few individuals colonise a new island

• A random mutation becomes common over several generations

• A natural disaster drastically reduces population size

• Humans breed animals for desirable traits

All of the following examples describes prezygotic isolating mechanisms EXCEPT

• elaborate and unique courtship display to identify mates

• reproductive organs that are physically incompatible

• hybrids that are viable but sterile

• different breeding times

The Eastern meadowlark has a whistle-like song, while the Western meadowlark has a more melodious, flute-like song Which reproductive isolation mechanism is involved?

• Behavioural

• Gametic

• Mechanical

• Temporal

Which situation best represents sympatric speciation?

• Two populations are separated by a river and evolve independently

• A population develops different mating preferences while living in the same habitat

• A small group migrates to a new island and forms a new species

• A species changes due to a climate shift across regions

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Two species of wildflowers have different length of floral tubes. Bees pollinate flowers with short tubes in the morning, while hummingbirds pollinate flowers with long tubes in the afternoon. Reproductive isolation that occur are... (Choose more than ONE answer)

• Mechanical isolation

• Temporal isolation

• Behavioural isolation

• Habitat isolation

Name the factor that leads to speciation shown in the diagram

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A small population of rabbits becomes isolated after a landslide. By chance, most surviving rabbits have white fur, even though the original population had a mix of colours. After several generations, the isolated group becomes mostly white. What is the best explanation?

• Natural selection favoured white fur

• Gene flow increased variation

• Genetic drift caused random changes in allele frequency

• Mutation created new white-fur alleles

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