Chapter 18, Problem 1SQ

In cladistics, the only taxon that is always correct as a clade is the _______.

1. a. genus
2. b. family
3. c. species
4. d. kingdom

Summary Introduction

Concept introduction: The taxon “species” is the basic unit of classification, and it is the unit of biodiversity. It comprises of organisms that resemble very close to each other. The term “clade” includes a group of organisms that are believed to comprise all the evolutionary descendants of a common ancestor.

Answer to Problem 1SQ

Correct answer: In cladistics, the only taxon that is always correct as a clade is the species. Therefore, option c. is the correct answer.

Explanation of Solution

Reason for the correct answer: Taxonomy is a biological practice of identifying different organisms, classifying them into different categories, and naming them. Organisms are classified according to their similarities and differences. Each hierarchy of taxonomy is known as taxa and species is the fundamental unit of this taxonomic classification. Cladogram is the pictorial representation of comparison of different groups of animals that are very closely-related with each other because of their shared ancestry. Therefore, both clade and species come under the same category, as the members come under them are much related to each other and also they share a common ancestry.

Option c. is given as “species”. The only taxon that is always the same as a clade is the species. Therefore, option c. is the correct answer.

Reason for the incorrect answers:

Option a. is given as “genus”. It is a taxonomic ranking used in biological classification. It comprises of several species, which are slighty different from each other. Hence, genus cannot be compared with a clade. Therefore, option a. is a wrong answer.

Option b. is given as “family”. In biological classification, it is one of the eight major taxonomic ranks, and it is divided into several subfamilies, which are intermediate ranks above the rank of a genus. As it is composed of several subdivisions, it does not have a group of members with the same characters as a clade. Therefore, option b. is a wrong answer.

Option d. is given as “kingdom”. It is a taxonomic category of the highest rank, grouping together all forms of life having certain fundamental characteristics in common. Hence, it cannot be compared with a clade. Therefore, option d. is a wrong answer.

Hence, options a., b., and d. are wrong answers.

Conclusion

Both the terms ‘species’ and ‘clade’ refers to the members in a group with a common ancestor.