Part F A population of birds colonizes an area in which the insects upon which t

Question

Part F 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? View Available Hint(s) O O O O Decreased fitness of the insects, allowing the birds to catch them more easily Increased fitness of large-beaked birds, leading to natural selection Increased fitness of the large-beaked birds, creating a new species Decreased fitness of small-beaked birds, creating a new species Submit Part G 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. View Available Hint(s) O True O False Submit

Explanation / Answer

Answers:

Part F: Option 2: Increase fitness of large beaked birds, leading to natural selection

Part G: True

Explanation for Part F:

Natural Selection can be defined as a process by which, organisms which are favorably adapted to the surrounding thrive and increase in population, by passing the trait which are favorable to the offspring.

Fitness is quantitatively measuring success of reproduction. Adaptation increases the fitness of the organisms, enable them in survival, and help them to reproduce. Adaptations are specific to environment which includes the habitat, predation, weather and competition with other populations.

In the given case, there is a change in predation, where, the birds with longer beaks can have more survival benefits. Eventually, birds having longer beaks, tend to reproduce more (more fitness) and pass their traits (longer beaks) to the new offspring (natural selection).

Thus, fitness of longer beak birds is increased, which leads to natural selection

Other options:

As mentioned earlier fitness is ability to produce more offspring, although predation decreases the number of insects, it do not affect the reproductive capacity of the insects as the predation and reproductive capacity are two independent parameters. Furthermore, allowing them to catch more easily also may not be true, because if fitness is reduced less number of organisms are produced, making them difficult to find and catch. Hence, option 1 is not true.

Option 3, refers to increased fitness of large beak birds, which is true upto here, but new species is not formed. There is only adaptation to the new habitat, which led to the increased length in beak but there is no generation of new species, hence, this option is false

Option 4 states decreased fitness of small beaked birds, creating a new species. There is decreased fitness of small beaked birds, but it is unlikely that new species are formed in the small beaked birds as there is high competition with large beak birds

Part G:

Allopatric speciation refers to the new species formation, due to reproductive isolation of species which are geographically separated, from the population of same species

Vicariance events refers to geographical changes that separate a species into isolated distributions

In the given example, flood is a vicariance event, which separated the frog population to opposite sides of the lake which may lead to the formation of new species.

This can be called as Allopatric speciation.

Hence the given statement is True

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