Chapter 4, Problem 1ER

Summary Introduction

To discuss: The examples of microevolution and macroevolution

Introduction:

Microevolution:

It refers to the small-scale evolution which results in the changes below the level of species. Microevolution occurs only over a few generations.

Macroevolution:

It refers to the large-scale evolution which results in the changes above the level of species. It occurs over many generations.

Explanation of Solution

Example of microevolution:

If there is a change in gene frequency over the few generations, it is called microevolution. For example, assume that the first generation of beetles has 75% of alleles that result in green color and 25% of alleles that result in orange color. If the second generation has 71% of the alleles that result in green color and 29% of the alleles that result in orange color, there is a microevolution.

Example of macroevolution:

If there is a change in gene frequency over many generations, it is called macroevolution. There is a creation of new species during macroevolution. For example, the horse at present evolved from an animal named eohippus 60 million years ago. There was a drastic change in the size and shape to the animal that led to a creation of new species.

Summary Introduction

To discuss: One of the forces of evolution that do not influence the macroevolution

Explanation of Solution

If there is a change in gene frequency over many generations, it is called macroevolution. The change during macroevolution is substantial. The four forces that lead to evolutionary change are mutation, natural selection, genetic drift, and gene flow. Out of the four forces of evolution, gene flow has less influence on macroevolution.

Gene flow refers to the transfer of genes from the parent to the offspring. As genes flow from the parent to the offspring, there is a reduction in genetic variation. Hence, there cannot be a substantial change or macroevolution because of the gene flow.

Conclusion

Microevolution refers to the change in gene frequency over a few generations whereas macroevolution refers to the substantial change in a particular species leading to the birth of a new species. Gene flow has less influence on macroevolution because the gene flow reduces genetic variation.