演化與物種形成：練習題

A large population of a single species is split into two separate populations by the formation of a new mountain range. Over time, these populations become reproductively isolated. What type of speciation has occurred?

A small population of lizards was geographically isolated on an island after a rise in sea level. Over many generations, the island population became a distinct species from the mainland population. Which statement best explains why allopatric speciation occurred in this scenario?

A population of snails shows a range of shell thicknesses. In an environment with a new predator that can easily crush thin shells, but finds very thick shells difficult to handle, the frequency of the allele for thick shells increases over several generations.

What type of selection and evolutionary change is this most likely to represent?

In a study of two closely related species of birds living in the same forest, it was observed that they remain distinct species because they have different mating calls, despite being physically capable of producing fertile offspring. This is an example of sympatric speciation.

Which of the following processes is most likely to lead to the accumulation of these genetic differences in a sympatric population?

In a population of birds, some individuals possess a beak shape that allows them to crack harder seeds. Explain how natural selection results in a change in the frequency of this allele during a period of drought when only hard seeds are available.

Explain how reproductive separation in a population of snails living on a single island could lead to the accumulation of different alleles in two distinct gene pools without the presence of a physical barrier.

Compare and contrast allopatric speciation and sympatric speciation, specifically identifying the primary isolating mechanism for each.

New species can arise through the process of speciation.

(a) Define the term sympatric speciation.
(b) State the primary requirement for allopatric speciation to occur.

A researcher is studying two populations of the same species of wildflower that are separated by a wide desert.

(a) Explain how genetic drift might lead to these two populations becoming different species, even if the environmental conditions in both locations are identical.
(b) Describe how reproductive separation eventually leads to the formation of a new species.