Page 86 - Biology_F5

Principles of classification

individual within a certain group/ Aristotle was taxonomically misleading.
taxon can give an insight into all other This is because bats are actually mammals
members within the same taxon.They with hairs on their bodies and they differ
all differ from members of cotton from birds that have feathers. They also
plants, genus Gossypium on the same differ from the butterflies, which are
features. insects.
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(f) It paves a way towards understanding The controversy of classification was
other disciplines, such as ecology, partly resolved by the taxonomist Carolus
medicine and pharmacology. For Linnaeus in the 1700s. This taxonomist
example, plants of the same genus retained the two major groups or kingdoms
may have similar ecological or of organisms, Animalia and Plantae.
growth requirements. Ecologically, Linnaeus introduced several taxa under
all plants under the bean/legume each kingdom to accommodate groups
family (Leguminosae/Fabaceae) have of organisms sharing more common
the ability to harbour Nitrogen fixing characteristics in which resemblance among
bacteria. Likewise, members under the organisms increased hierarchically down
same genus may produce secondary the groups. He classified organisms based
metabolites or biochemicals with on their shared natural features.
similar medicinal or pharmacological
properties. Since then, classification has been very
dynamic, and has gone through five systems.
These are artificial system, natural system,
2.2 Classification systems
phyletic classification, phenetics, and
phylogenetics or cladistics. In artificial
Task 2.2 classification approach, only one or a
Read from different internet sources, few observable characteristics were used.
and biology books about classification Natural classification approach grouped
systems, then make short notes.
together individuals reflecting how they
occur in nature. This approach did not
Organisms can be grouped in many ways reflect evolutionary history though
for convenience of studying them and it used many characteristics. Natural
to fully appreciate their comparative classification approach was followed by
evolutionary relatedness. Traditionally, phyletic classification approach based
all organisms were grouped by Aristotle
as either animals or plants with just on Charles Darwin’s publication; “The
a few sub-groups in each group. This origin of species by means of natural
classification had shortfalls, as it did not selection” and the development of modern
consider the evolutionary relationship theory of chromosomes. In the phyletic
among organisms grouped together. For system, organisms were classified from
example, grouping into one or single group simple to complex, reflecting evolutionary
of all flying animals such as birds, bats, history. However, assigning of ancestral
moths and butterflies, as propounded by or derived status was done subjectively.

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