Biology 101 Test 4: Taxonomy, Systematics, and Nomenclature Review

This biology test assesses understanding of key concepts in taxonomy and phylogeny. The first question requires an explanation of the purpose of a type specimen in taxonomy, including how it addresses questions of nomenclature, with an example like the Lord Howe Island stick insect. The second question focuses on why primitive character states cannot accurately determine phylogenetic relationships, with examples such as the presence of hair. The third section defines and explains systematics, numerical systematics, biochemical systematics, experimental systematics, taxonomy, autapomorphy, and the principle of homonymy, providing a comprehensive overview of these biological concepts. The student demonstrates a strong understanding of these topics, providing detailed explanations and relevant examples.

Test 4. The test should be your own work, ideas, and writing. It will be due at the end of the
day Thursday, August 1. For full credit, 10-point questions should include a comprehensive
discussion with examples and/ or explanation.
1. Explain the purpose of a type specimen in taxonomy and give at least one example of how
the type would be used to address questions of nomenclature. 10 pts
Type specimens are physical specimens that generally kept in a museum or herbarium as
research collection. However, if a type specimen is not available, an image of an individual
of that taxon can be used as the type specimen. These are used to describe the characteristics
of the taxon.
During the identification and nomenclature of an organism, the characteristics of the newly
found organism are matched with the type specimen and accordingly, the recently discovered
specimen is named and classified. This approach is commonly used because most of the
organisms within a species have similar characteristics; thus, it will be difficult to classify the
organisms without type specimen. The purpose of a type specimen in taxonomy is the image
of an individual of that taxon. It serves the function of depiction characteristics that are
representative of a taxon, i.e. attributes that characterize a taxon and thus help in the
classification. Therefore, the type would be used to address questions of nomenclature
because it would be a representation of the traits of a taxon. For example, serving as an
anchor to centralize the defining features of a particular taxon as it acts as the name bearer for
a species. One of the examples of this is a specimen of the Lord Howe Island stick insect
(Dryococelus australis). The Type specimen for this species are being kept in London at the
Natural History Museum.

2. Explain why primitive character states cannot be used to determine phylogenetic
relationships. 10 pts
Phylogenetic relationships are presented in the form of a tree. It is to hypothesize the
evolutionary relationship among different groups of organisms.
Primitive characters are transferred from parents to their offspring as it is. They do not show
any evolution. Thus, they cannot be used to determine the evolutionary phylogenetic
relationship.
E.g., The presence of hair among mammals is the primitive character state which does not tell
any evolution in the mammals, like the evolution of a hairless mammal such as whale.
Primitive character states cannot be used to determine phylogenetic relationships accurately
because in many cases, environmental factors affect the physical characteristics. Also, the
presence of analogous organs can deviate the result from an actual relationship. For example,
bats have wings and can fly, but they are considered as mammals and avian-like other birds
because of the difference in origin of related structures, for example, in this scenario, wings.
Hence, the genetic makeup of an organism is the prime method that can give the correct
assumption about the phylogenetic relationship.
3. Describe and explain each of the following: 2 pts each
Systematics can be defined as the arrangement of living organisms depicting association
between different organisms as they evolved through time. They are illustrated as an
evolutionary tree, also known as cladogram of the phylogenetic tree; Different kind of
branches are used for understanding the relationship among organisms across time. The other
type of branches are:
a) Numerical systematics/Biometry: this utilizes the biological statistics for the classification
of organisms.

b) Biochemical systematics uses biochemical materials of the cell including nucleus,
cytoplasm and other organelles.
c) Experimental systematics: utilizes factors such as mutation, genetic divergence and other
evolutionary units for the classification of organisms
Biological systematics is the study of the diversification of the different forms of living and
finding the relationships among them through time. Thus it is used for understanding the
evolutionary history of life forms on Earth.
Taxonomy: the arrangement of living organisms according to hierarchy. Organisms are
classified into a taxon based on shared characteristics and then are given rank. The broad
classification is into domain and kingdom, and the specific classification includes genus and
species. The seven main taxonomic groups include kingdom, phylum, class, order, family,
genus and species. Taxonomy is the branch of science that is concerned with classification, of
organisms mainly based on a predetermined system.
Autapomorphy: Autapomorphy can be defined as a trait specific to a given taxon. It is not
found in another taxon or any other related taxon. An autapomorphy is a particular
characteristic or attribute that is unique to a taxonomic group. This feature is believed to have
evolved within a family tree; which can be used to identify it, i.e. separate one group from the
other.
Principle of Homonymy: International code of zoological nomenclature (ICZN) is a
convention in zoology that sets the rules regarding the scientific naming of organisms. The
name is given by using six central principles and principle of homonymy is one of them.
Principle of homonymy strictly says that the name of an organism or a taxon must be unique.
Any name in particular spelling must be used only once and once published that name should
not be used for other nomenclature. According to the Principle of Homonymy a guiding

principle of the International Code of Zoological Nomenclature; any one name, in one
spelling, should be used only once.