13.1 Concept of Species

The original concept of species has undergone a considerable change during the progress of taxonomy. John Ray (1627-1705) was the first to distinguish genus and species. However, the clear morphological concept of species was first given by Linnaeus (1707-1778). Later on, Darwin proposed the biological concept of species. The concept was further modified by Ernst Meyr.

Carolus Linnaeus

Morphological concept of species by Linnaeus. A species is the group of individual which resemble each other in most major morphological (vegetative and reproductive) characteristics.

Biological concept of species by Darwin. In addition to morphology, the biological concept also takes into consideration ecology, geography, cytology, physiology, behavior, etc.

According to the biological concept, a species is a group of individuals which resemble each other in morphological, physiological, biochemical, and behavioral characteristics. These individuals are capable of breeding with each other under natural conditions, but are unable to breed successfully with members of other species.

Thus, species is a group of fertile organisms that can interbreed and produce fertile offspring only among themselves.

The recent trend is to consider species as the groups of actually or potentially interbreeding natural populations of closely resembling individuals (Ernst Meyr).

A species is considered to be the smallest, most basic unit of classification in most of the systems. It was thought to be an indivisible, stable and static unit (taxon). However, in modern taxonomy, sub-divisions of species, such as sub-species and populations, have been created which aid in our understanding through classification.

Table of Contents

13.0 - Introduction
13.1 Concepts of Species
13.2 Taxa and Categories
13.3 Systematic Hierarchies
13.4 Binomial Nomenclature
13.5 Principles of Classification

Chapter 14