91Ó°ÊÓ

Prior to 1800 in England, the typical moth of the species Biston betularia (peppered moth) had a light pattern. Dark colored moths were rare. By the late 19th century, the light-colored moths were rare, and the moths with dark patterns were abundant. The cause of this change was hypothesized to be selective predation by birds (J.W. Tutt, 1896). During the industrial revolution, soot and other wastes from industrial processes killed tree lichens and darkened tree trunks. Thus, prior to the pollution of the industrial revolution, dark moths stood out on light-colored trees and were vulnerable to predators. With the rise of pollution, however, the coloring of moths vulnerable to predators changed to light. Commonly used in biology textbooks, the peppered moth is a classic example of evolutionary change in action. The example describes changes in a population’s allele frequencies-a small-scale change, evolutionarily speaking. The presence of both light and dark forms within the gene pool is demonstrated by the story, but the peppered moth stays a peppered moth. Which scenario, if it were to occur, would be a model for large-scale evolutionary change? a. Conditions change such that the dark form of the moth is favored and the light form is diminished in the population due to predation. Conditions change again, the dark form is vulnerable, and the light form returns to prevalence. b. Conditions change such that the dark form of the moth is favored and the light form is eradicated in the population due to predation. Conditions change again, the dark form is vulnerable, and the dark form is eradicated due to predation. c. Conditions change such that dark form of the moth is favored and the light form is diminished in the population due to predation. Conditions change again, and both forms have equal prevalence. d. Conditions change such that dark form of the moth is favored and the light form is eradicated in the population due to predation. Conditions change again, the dark form is vulnerable. It develops an adaptation that shields it from predation.

Step by step solution

01

Understanding Small-Scale Evolutionary Change

The exercise discusses how the frequency of light and dark forms of the peppered moth changes due to environmental conditions. This type of change, affecting allele frequencies within a population, is known as microevolution.

02

Defining Large-Scale Evolutionary Change

Large-scale evolutionary change, or macroevolution, involves significant evolutionary transformations, such as the development of new adaptations or species.

03

Evaluate Each Scenario

Examine each provided scenario to determine if it fits the definition of large-scale evolutionary change. Look for scenarios where a significant adaptation or new trait develops.

04

Analyze Option A

Option A describes changes in the prevalence of light and dark forms of the moth without mentioning any new adaptations or traits. This is a continuation of microevolution, not macroevolution.

05

Analyze Option B

Option B also discusses changes in light and dark form prevalence due to predation, without any mention of development of new traits or adaptations. This remains within the realm of microevolution.

06

Analyze Option C

Option C similarly describes a scenario where the prevalence of the forms changes but does not introduce any new adaptations. Therefore, it is not macroevolution.

07

Analyze Option D

Option D describes a scenario where the dark form develops an adaptation that shields it from predation, indicating the emergence of a new trait. This is a significant change and fits the definition of macroevolution.

08

Conclusion

Based on the definitions and analysis, option D is the only scenario that fits the criteria for a large-scale evolutionary change.

Unlock Step-by-Step Solutions & Ace Your Exams!

• Full Textbook Solutions

  Get detailed explanations and key concepts

• Unlimited Al creation

  Al flashcards, explanations, exams and more...

• Ads-free access

  To over 500 millions flashcards

• Money-back guarantee

  We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Microevolution

Microevolution refers to small-scale changes in the genetic makeup of a population. For example, the frequencies of different alleles (versions of a gene) within a population may shift over time. These changes are often observed within a single species and can result from factors like natural selection, mutation, gene flow, or genetic drift. With the peppered moth population, we see microevolution in action
when the allele frequencies for light and dark coloration change due to environmental pressures. This type of evolution doesn't create new species but instead causes variations within the existing species.

Selective Predation

Selective predation occurs when predators preferentially target specific traits in their prey, leading to changes in the prey population. In the case of the peppered moth during the Industrial Revolution, birds preyed more heavily on moths that stood out against the environment:
light-colored moths on darkened, soot-covered trees. This selective predation was responsible for the higher survival rates of dark-colored moths, causing a shift in the population. Selective predation serves as a driving force for natural selection, influencing which traits become more common over generations.

Peppered Moth Evolution

The evolution of peppered moths is a classic example of how environmental changes can drive natural selection. Before the Industrial Revolution, the lighter-colored moths were well-camouflaged against the lichen-covered trees, and dark moths were rare. However, with pollution killing lichens and darkening trees
dark moths became better camouflaged, reducing their risk of predation and allowing them to become more common in the population. The genetic shift between light and dark forms in the population highlights how natural selection operates, favoring traits that enhance survival in changing environments.

Allele Frequencies

Allele frequencies define how often an allele appears within a population. They can change over time due to factors like selection pressures, mutations, or random genetic drift. The peppered moth example beautifully illustrates these dynamics. As environmental conditions changed,
the frequency of the allele for dark coloration increased while the frequency of the allele for light coloration decreased. Tracking these changes in allele frequencies helps biologists understand microevolutionary processes at work. In essence, it's about how certain traits become more or less common due to varying survival and reproduction rates.

Industrial Revolution Pollution

The Industrial Revolution had significant impacts on the environment, including heavy pollution that altered natural habitats. In the context of peppered moths, soot from factories killed lichens on trees and darkened their bark, changing the background against which the moths were camouflaged.
Light-colored moths, once safe from predators on lichen-covered trees, became highly visible on soot-darkened trees, increasing their predation risk. Conversely, dark-colored moths, previously rare and susceptible to predation, found themselves better camouflaged and thus, more likely to survive and reproduce. This environmental shift directly influenced the evolutionary path of the species.