Chapter 20, Problem 1TY

Macroevolution refers to evolutionary changes that

1. occur in multicellular organisms.
2. produce new species and groups of species.
3. occur over long periods of time.
4. cause changes in allele frequencies.
5. occur in large mammals.

Summary Introduction

Introduction:

Microevolution is the change in allele frequencies within a population over time. Microevolution is a result of mutations, natural selection, gene flow and genetic drift. In microevolution small differences in population occur compared to macroevolution. Microevolution over long period of time leads to speciation which is described under macroevolution.

Answer to Problem 1TY

The correct answersisoption (b) produce new species and groups of species and option

Explanation of Solution

Explanation/justification for the correct answer:

Option (b) − Macroevolution is the large-scale evolution which occurs at the level of species and above. It describes the differences between two closely related species; for instance, western meadowlark and eastern meadowlark birds. They are two different species even though the morphological characteristics are similar. They cannot mate due to reproductive isolation. Microevolution also describes that the all life forms are from a single origin. So, option (b) is the correct answer.

Explanation for incorrect answer:

Option (a) − Macroevolution is usually defined as the innovation of morphological innovations in multicellular organisms. But there are some microbial experimental evidences of macroevolution in unicellular level.

Option (c) − the changes observed in macroevolution occurs over long time period. The changes happen in microevolution occurs over a short period of time relatively to the changes occur in macroevolution in evolutionary wise. So option (c) is incorrect.

Option (d) causes changes in allele frequencies. Genetic information gets altered or rearranged in microevolution, not macroevolution. Alteration of genetic information leads to changes in allele frequencies. The microevolution occurs over a short time scale. The changes occur in genetic level causes the phenotypic changes which are naturally selected overtime. So, microevolution often lead to macroevolution. Option (d) is incorrect.

Option (e) occurs in large mammals. This option is incorrect as macroevolution can be taken place in almost every kind of population. Birds, fish, reptiles, bacteria etc.

Conclusion

Macroevolution refers to evolutionary changes that produce new species and group of species. So, option (b) is correct.