Maria Emilia Espinosa
HOW TO CLASSIFY? Read the passage and answer the questions which follow.
It has been suggested that only 1 in 10 of the plant and animal species in the world have been
described and classified. Hundreds, and sometimes thousands, of new species are discovered and
described every year.
When a new organism is discovered, it is given a binomial. Taxonomists attempt to describe its
morphological characteristics, so that other biologists will be able to recognize it, and distinguish
it from other similar organisms. Further studies, however, may be required before it can finally
be decided whether the organism is a truly new species, or simply a morphological variant of a
species which is already known and named.
A large majority of known species, and of the new ones being discovered, are insects. Of these,
the beetles make up by far the largest group; one on four of all known species are beetles. In one
study in a Panamanian rain forest, it was found that nine individuals of the tree Luehea
seemannii had 1200 species of beetles living on them, of which 163 species were estimated to be
found only on that species of tree. As the number of tropical rain forest species is about 50,000,
it was calculated that there could be 8,150,000 different species of beetles found on those trees.
Simply describing large numbers of species would produce an unmanageable list. To handle such
large quantities of data, taxonomists must classify species. The earliest systems of classification
were artificial. Plants, for example, can be classified as edible, medicinal or poisonous. Modern
classification systems now attempt to classify organisms in a hierarchical, phylogenetic manner.
1. Define the following terms:
a. binomial (line 4);
binominal have two definitions, the most important and common one is that binominal is
used of the system by which every single plant and animal receives two names, one name
indicates the genus, the other the species, to which it belongs.
b. hierarchical (line 18);
It is any system of animals, persons or things ranked one above the other.
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Maria Emilia Espinosa
2. When a new organism is discovered, further studies may be required before it can
finally be decided if it is a new species. Suggest what these studies might be. (Line 6)
Further studies may be required before it can finally be decided because the they have to make
sure that the organism is a truly new species otherwise it can just be a simply a morphological
variant of a species which is already known and named.
3. In what way is a phylogenetic classification system better than an artificial one?
Artificial system of classification is based on characters that do not indicate natural relationship
Phylogenetic classification of organisms is based on their expected evolutionary histories and
relationships
Phylogenetic is an exact classification.
a. In the Panamanian rain forest study, what assumptions have been made in
calculating that there may be 8,150,000 different species of beetles living on rain
forest trees? (Lines 13-14)
They assume that there are 1200 beetles species living in a tree but they just focus one
specie, they have to see more trees and more species, more individuals
b. Suggest one way in which this study could realistically be extended to give a more
reliable estimate of the number of beetle species in the rain forest.
The study could be extended by analysing more individuals of the same species of trees.