Chapter 17, Problem 10A

Summary Introduction

To explain:

Difference between phylogeny and character.

Introduction:

Classification systems have changed over times as information has increased, so the different species concept were given such as typological species concept according to which species were thought to be a distinctively different group of organisms based on physical similarities. But as species changes over time, concepts have been replaced. According to biological concept of species, a species refers to a group of similar individuals that are able to interbreed and produce fertile offspring. According to phylogenetic species concept, two or more groups that evolve independently from an ancestral population are classified as different species.

Explanation of Solution

Phylogeny is the study of relationships among different groups of organisms and their evolutionary development. Phylogeny challenges to trace the evolutionary history of all life on the planet. It is based on the phylogenetic hypothesis that all living organisms share a common ancestry.

Character refers to inherited features that vary among species and organisms are compared based on similar characters.Characters can be morphological or biochemical.

Morphological characters are external characters and shared morphological characters suggest that species are related closely and evolve from recent common ancestors. Examples are keen eyesight, hooked beaks and talonedfeet are common characters between hawks and eagles.

Biochemical characters are those in which amino-acids and nucleotides are used to determine evolutionary relationships among species. Chromosomal structure and number are also considered as strong evidences for determining species similarities.

The morphological and biochemical characters form the basis of phylogeny as characters are useful to determine evolutionary history of organisms.