MODULE 3
Biodiversity
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Term used to describe the variety of all life on Earth.
Foundation of all life on Earth
Species, characteristics, habitats
More biodiversity, more secure life
Biodiversity loss -> poor water, less food, flood, fire, etc
Introduction to Biosystematics
Biosystematics is the subdiscipline of biology that deals with the study of the diversity of life. It involves
taxonomic processes such as discovery, nomenclature, description, classification, and identification of
species, whose relationships are interpreted on the basis of evolutionary history.
Discovery - around 1.7 million species have so far been discovered, named and described, out of the
estimated 8.74 million species that exist on earth.
Nomenclature - the study of the system and methods of naming organisms. It also includes
the construction, interpretation, and application of the regulations governing the naming system.
Description of a taxon is a statement of its characters, which thus constitutes the definition of the taxon.
Characters contributing to the description are known as taxonomic characters or systematic characters.
Meanwhile, a diagnosis is a shortened description covering only diagnostic characters which distinguish
the taxon from related taxa.
Classification as a process, is the production of a logical system of categories, each containing any
number of taxa, which allows easy storage, retrieval, and use of information about organisms.
Classification, therefore, must show the hierarchical relationship of included taxa by rank or position.
Identification or determination involves the determination of the name of an organism with reference to a
previously established classification and identification system. Classification precedes identification.
Identification also involves the diagnostic delimitation and naming of a taxon and the determination of the
taxonomic group to which that taxon belongs using identification devices like an identification key.
Schemes of Biological Classification
Carolus Linneaus, the father of taxonomy, classified organisms as either plants or animals. This system of
putting all living things under either Kingdom Plantae or Kingdom Animalia is known as the twokingdom scheme of biological classification.
Later on, during the time in the late 16th century when microscopes were developed, a new group of
minute organisms that were once invisible to the naked eye was revealed. Ernst Haeckel proposed that a
third kingdom, named Protista, be created to accommodate a group of unicellular organisms such
as protozoa, algae, and bacteria, which exhibit both plant-like and animal-like characters. This is known
as the three-kingdom scheme of biological classification.
In 1938, Herbert Copeland proposed the four-kingdom scheme of biological classification
naming Monera as the fourth kingdom to include both bacteria and blue-green algae (now called
cyanobacteria). He pointed out that there are many fundamental characteristics rarely seen in other
organisms but commonly shared by bacteria and blue-green algae.
The most widely used classification system, however, is that proposed by Robert Whittaker in the 1950s,
which separates the non-photosynthetic Fungi from the rest of the plant kingdom. Whittaker pointed out
that fungi do not produce food by photosynthesis as plants do, nor ingest food as animals do. They secrete
digestive enzymes to break down food before absorbing it into their cells. This five-kingdom scheme of
biological classification, therefore, recognizes five major groups of organisms, namely, prokaryotes
of Kingdom Monera, yeasts and mushrooms of Kingdom Fungi, green algae and land plants
of Kingdom Plantae, metazoans of Kingdom Animalia and the remaining eukaryotes such as protozoa,
and unicellular and simple multicellular algae that include diatoms, red and brown algae
of Kingdom Protista.
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In the 1970s, advances in molecular biology that permitted comparative analysis of DNA structures
yielded new information that prompted a review of the five-kingdom system of classification. Carl Woese
proposed a six-kingdom classification system that divided Monera into two kingdoms,
the Archaebacteria and Eubacteria and placed eukaryotic organisms into the Kingdoms Plantae,
Animalia, Fungi, and Protista. He and Ernest Mayr later advocated the use of a new category called the
domain. This new system is called the two-domain classification scheme as follows:
Domain Prokaryota (Monera)
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Subdomain Eubacteria
Subdomain Archaebacteria
Domain Eukaryota
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Subdomain Protista
Subdomain Metabionta
o Kingdom Metaphyta (Plantae)
o Kingdom Fungi
o Kingdom Metazoa (Animalia)
They later proposed the three-domain classification scheme, splitting prokaryotes into two domains,
Bacteria, and Archaea.
Domain Bacteria
Domain Archaea
Domain Eukarya
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Subdomain Protista
Subdomain Metabionta
o Kingdom Metaphyta (Plantae)
o Kingdom Fungi
o Kingdom Metazoa (Animalia)
As we can see from the discussion, there are so many different schemes that we can choose to use to
classify organisms. Many other classification schemes may be proposed in time. We would therefore like
to emphasize the following:
1. Classification is man-made, thus differences in opinion are to be expected;
2. Classification is arbitrary, thus changes are to be expected as taxonomists are able to gather
new information about organisms; and
3. Classification is not the basic biological concept, DIVERSITY OF LIFE is.
Let us not forget why we classify organisms. We do it because it facilitates the proper naming and
determination of the position of a species. It provides an easy scheme for species identification. It ensures
an orderly system of documentation and compilation of information about organisms. It allows the
systematic retrieval of this information when necessary.
Moreover, we group organisms so we can better appreciate their similarities and differences and use them
to better understand the changes that occurred among them through time.
Binomial Nomenclature
Common names for organisms—such as monkeys, birds, and lilies—convey meaning in casual usage, but
they can also cause confusion. Each of these names, for example, refers to more than one species.
Moreover, some common names do not accurately reflect the kind of organism they signify. Consider
these three “fishes”: jellyfish (a cnidarian), crayfish (a small, lobster-like crustacean), and silverfish (an
insect). And, of course, a given organism has different names in different languages.
Different organisms that are casually called a "fish" - a jellyfish, a crayfish, and a silverfish. All three
organisms are from different taxonomic classifications.
To avoid ambiguity when communicating about their research, biologists refer to organisms by Latin
scientific names. The two-part format of the scientific name, commonly called a binomial, was instituted
in the 18th century by Carolus Linnaeus. The first part of a binomial is the name of the genus (plural,
genera) to which the species belongs. The second part called the specific epithet, is unique for each
species within the genus. An example of a binomial is Panthera pardus, the scientific name for the
leopard. Notice that the first letter of the genus is capitalized and the entire binomial is italicized. (Newly
created scientific names are also “latinized”: You can name an insect you discover after a friend, but you
must add a Latin ending.) Many of the more than 11,000 binomials assigned by Linnaeus are still used
today, including the optimistic name he gave our own species—Homo sapiens, meaning “wise man.”
Hierarchical Classification
In addition to naming species, Linnaeus also grouped them into a hierarchy of increasingly inclusive
categories. The first grouping is built into the binomial: Species that appear to be closely related are
grouped into the same genus.
For example, the leopard (Panthera pardus) belongs to a genus that also includes the African lion
(Panthera leo), the tiger (Panthera tigris), and the jaguar (Panthera onca). Beyond genera, biologists
employ progressively more comprehensive categories of classification. The classification system named
after Linnaeus, the Linnaean system, places related genera in the same family, families into orders, orders
into classes, classes into phyla (singular, phylum), phyla into kingdoms, and, more recently, kingdoms
into domains.
The named group at any level of the hierarchy is called a taxon (plural, taxa). In the leopard
example, Panthera is a taxon at the genus level, and Mammalia is a taxon at the class level that includes
all the many orders of mammals. (Note that in the Linnaean system, taxa broader than the genus are not
italicized, though they are capitalized.)
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Binomial Nomenclature
Common names for organisms—such as monkeys, birds, and lilies—convey meaning in casual usage, but
they can also cause confusion. Each of these names, for example, refers to more than one species.
Moreover, some common names do not accurately reflect the kind of organism they signify. Consider
these three “fishes”: jellyfish (a cnidarian), crayfish (a small, lobster-like crustacean), and silverfish (an
insect). And, of course, a given organism has different names in different languages.
Different organisms that are casually called a "fish" - a jellyfish, a crayfish, and a silverfish. All three
organisms are from different taxonomic classifications.
To avoid ambiguity when communicating about their research, biologists refer to organisms by Latin
scientific names. The two-part format of the scientific name, commonly called a binomial, was instituted
in the 18th century by Carolus Linnaeus. The first part of a binomial is the name of the genus (plural,
genera) to which the species belongs. The second part called the specific epithet, is unique for each
species within the genus. An example of a binomial is Panthera pardus, the scientific name for the
leopard. Notice that the first letter of the genus is capitalized and the entire binomial is italicized. (Newly
created scientific names are also “latinized”: You can name an insect you discover after a friend, but you
must add a Latin ending.) Many of the more than 11,000 binomials assigned by Linnaeus are still used
today, including the optimistic name he gave our own species—Homo sapiens, meaning “wise man.”
Hierarchical Classification
In addition to naming species, Linnaeus also grouped them into a hierarchy of increasingly inclusive
categories. The first grouping is built into the binomial: Species that appear to be closely related are
grouped into the same genus.
For example, the leopard (Panthera pardus) belongs to a genus that also includes the African lion
(Panthera leo), the tiger (Panthera tigris), and the jaguar (Panthera onca). Beyond genera, biologists
employ progressively more comprehensive categories of classification. The classification system named
after Linnaeus, the Linnaean system, places related genera in the same family, families into orders, orders
into classes, classes into phyla (singular, phylum), phyla into kingdoms, and, more recently, kingdoms
into domains.
The named group at any level of the hierarchy is called a taxon (plural, taxa). In the leopard
example, Panthera is a taxon at the genus level, and Mammalia is a taxon at the class level that includes
all the many orders of mammals. (Note that in the Linnaean system, taxa broader than the genus are not
italicized, though they are capitalized.)
Binomial Nomenclature
Common names for organisms—such as monkeys, birds, and lilies—convey meaning in casual usage, but
they can also cause confusion. Each of these names, for example, refers to more than one species.
Moreover, some common names do not accurately reflect the kind of organism they signify. Consider
these three “fishes”: jellyfish (a cnidarian), crayfish (a small, lobster-like crustacean), and silverfish (an
insect). And, of course, a given organism has different names in different languages.
Different organisms that are casually called a "fish" - a jellyfish, a crayfish, and a silverfish. All three
organisms are from different taxonomic classifications.
To avoid ambiguity when communicating about their research, biologists refer to organisms by Latin
scientific names. The two-part format of the scientific name, commonly called a binomial, was instituted
in the 18th century by Carolus Linnaeus. The first part of a binomial is the name of the genus (plural,
genera) to which the species belongs. The second part called the specific epithet, is unique for each
species within the genus. An example of a binomial is Panthera pardus, the scientific name for the
leopard. Notice that the first letter of the genus is capitalized and the entire binomial is italicized. (Newly
created scientific names are also “latinized”: You can name an insect you discover after a friend, but you
must add a Latin ending.) Many of the more than 11,000 binomials assigned by Linnaeus are still used
today, including the optimistic name he gave our own species—Homo sapiens, meaning “wise man.”
Hierarchical Classification
In addition to naming species, Linnaeus also grouped them into a hierarchy of increasingly inclusive
categories. The first grouping is built into the binomial: Species that appear to be closely related are
grouped into the same genus.
For example, the leopard (Panthera pardus) belongs to a genus that also includes the African lion
(Panthera leo), the tiger (Panthera tigris), and the jaguar (Panthera onca). Beyond genera, biologists
employ progressively more comprehensive categories of classification. The classification system named
after Linnaeus, the Linnaean system, places related genera in the same family, families into orders, orders
into classes, classes into phyla (singular, phylum), phyla into kingdoms, and, more recently, kingdoms
into domains.
The named group at any level of the hierarchy is called a taxon (plural, taxa). In the leopard
example, Panthera is a taxon at the genus level, and Mammalia is a taxon at the class level that includes
all the many orders of mammals. (Note that in the Linnaean system, taxa broader than the genus are not
italicized, though they are capitalized.)