Chapter 25: Problem 4

The genetic difference between two Drosophila species, \(D\). heteroneura and \(D .\) sylvestris, as measured by nucleotide diversity, is about 1.8 percent. The difference between chimpanzees \((P\) troglodytes and humans (H. sapiens) is about the same, yet the latter species are classified in different genera. In your opinion, is this valid? Explain why.

Short Answer

Expert verified

Explain your opinion. Answer: The classification of species into different genera based on genetic differences can be considered valid, not solely relying on the genetic component, but also taking into account phenotypic differences, ecological niches, and other factors that set species apart from each other. In the case of humans and chimpanzees, the unique cognitive abilities of humans are a significant aspect that validates their classification into different genera despite having a similar genetic difference as two Drosophila species. Therefore, it is important to consider an overall framework of species differences, rather than just focusing on genetic differences.

Step by step solution

Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, which contributes to the variation between individuals of the same species. It is usually measured by the nucleotide diversity, which is the average number of nucleotide differences between two individuals of the same species. #Step 2: Compare the genetic differences between the given species pairs#

In this exercise, we are given that the genetic difference between two Drosophila species, \(D\). heteroneura and \(D.\) sylvestris, is about 1.8 percent. Similarly, the genetic difference between chimpanzees (\(P\) troglodytes) and humans (H. sapiens) is also 1.8 percent. #Step 3: Explain the current classification system and criteria for different genera#

The classification of species into different genera is based on various criteria, including genetic differences, phenotypic differences, ecological niche, and evolutionary history. Many taxonomists may use different weighting of these criteria in determining whether species should be classified into different genera. #Step 4: Discuss the case for classifying humans and chimpanzees in different genera based on their genetic differences#

One argument for classifying humans and chimpanzees in different genera is that they have different phenotypic characteristics, such as body size, brain size, locomotion, and other physiological and morphological differences. In addition, humans have developed complex culture and cognitive abilities that distinguish them from chimpanzees. Some scientists may argue that these differences are enough to warrant separation into different genera, despite the relatively small genetic difference. #Step 5: Discuss the case against classifying humans and chimpanzees in different genera based on their genetic differences#

On the other hand, some scientists may argue that the genetic similarity between humans and chimpanzees should be the primary criterion for classifying them into the same genus. They may claim that the phenotypic differences and other factors mentioned earlier are not significant enough to warrant classification into different genera, especially since the genetic difference between the two species is similar to the difference between two Drosophila species that are classified in the same genera. #Step 6: Provide your own opinion on the validity of the classification and explain why#

In my opinion, the classification of humans and chimpanzees in different genera is valid, not solely based on their genetic differences, but on the phenotypic differences, ecological niches, and particularly the unique cognitive abilities of humans, which set them apart from chimpanzees and other primates. The classification system should take into account the overall framework of species differences, rather than just focusing on genetic differences.