Identifying, naming, and classifying species
SPECIES: is a group of organisms that can interbreed in nature and produce fertile offspring.
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Scientists have identified about 2 million species on Earth. Although, scientists estimate that there
are between 5-20 million species!
There are millions of species on Earth – from bacteria, to plants, to insects, to carnivorous animals.
It is important to know how to classify and identify different species:
 Farmers and gardeners need to identify different types of weeds
 Doctors need to know which species might infect patients; and which can be used as a
prescription for medication
Identifying Species: Using Species Concepts
Since scientists have trouble coming up with just 1 definition for species, they use species concepts:
Species Concept
Description
Advantages and Disadvantages
Morphological
-Focuses on morphology (the body
Advantage
species concept
shape, size and other structural features. -Relative simplicity makes it widely used,
-Relies on comparing measurements and particularly for plants.
descriptions of similar organisms.
Disadvantage
-Having to decide how much difference
between individuals is too much variation.
Biological
-Focuses on similar characteristics and
Advantage
species concept
the ability of organisms to interbreed in
-It is widely used by scientists
nature to produce viable and fertile
offspring.
Disadvantage
-It cannot always be applied: if 2
populations are physically separated, they
cannot reproduce.
-It cannot be applied to organisms that
reproduce asexually.
Phylogenetic
-Focuses on evolutionary relationships
Advantage
species concept
among organisms.
-It can be applied to extinct species.
-A species is defined as a cluster of
-It considers information about
organisms that is distinct from other
relationships among organisms learned
clusters, and shows a pattern of
from DNA analysis.
relationship among the organisms.
-Two organisms can be found to be
Disadvantage
related by DNA and have a common
-Evolutionary histories are not known for
ancestor, even if now they are now 2
all species.
separate species.
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MORPHOLOGY: the branch of biology that deals with the structure or form of organisms.
PHYLOGENY: the evolutionary history of a species
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Naming Species
o Different countries, even different regions, can name the same organism by many names.
o For example) The groundhog is also called a woodchuck, a whistle pig, or a forest marmot.
o Therefore, having a standard system for naming organisms is essential.
o TAXONOMY: Is the branch of biology that identifies, names, and classifies species.
o Carl von Linne (aka: Carolus Linnaeus) is known as the Father of Taxonomy. He developed a system for
naming species:
o BINOMIAL NOMENCLATURE: The system of giving a two-word Latin name to each species – the
first part is the genus and the second part is the species.
 Binomial refers to having 2 parts; and nomenclature means a naming system.
 The first part of the species name (or scientific name) is the GENUS (the taxonomic group of a
closely related species).
 The name is italicized when typed; with the genus name capitalized and the species name in lower
case. Example) Homo sapiens (humans)
 If the species name (scientific name) is written by hand, both parts of the name are underlined.
Classifying Species
o Species concepts allow us to determine what groups of organisms make up a species.
o Binomial nomenclature allows us to apply a formal name for each of those species.
o CLASSIFICATION: is the grouping of organisms based on a set of criteria that helps to organize and indicate
evolutionary relationships.
o Hierarchical Classification:
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A hierarchy is an arrangement of items in which the items are identifies as being above,
below, or at the same level compared to other items.
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Because nested classifications have categories arranged by hierarchies, this method is called
HIERARCHICAL CLASSIFICATION. It organizes species in categories from most general
to most specific.
Un-nested Classification
Sports
Hockey
Soccer
Tennis
Golf
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Nested Classification
Team
Sports
Hockey
Soccer
Sports
Individual
Sports
Tennis
Golf
Taxonomic Categories Used to Classify Organisms:
 Taxonomic categories are the groupings, arranged in a hierarchy, that are used to classify organisms
that have been named and identified.
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In most cases, a species is classified by assigning it membership in 8 nested categories. Each of these 8
taxonomic categories is known as a RANK (a level in a classification scheme, such as phylum or order).
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The name of each rank is called a TAXON (a named group of organisms such as phylum Chordata or
order Rodentia)
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As you move down the ranks, the information for classifying a specific species becomes more precise.
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(see page 15: Table 1.2 for the Taxonomic Classification of the Grey Wolf)
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Within the domain Eukarya are 4 kingdoms – and the grey wolf is placed in the animal kingdom. The
kingdom has fewer species in it than a domain. However, because the animal kingdom includes insects
and all other animals, it still contains more than a million species. Within the animal kingdom is the
chordate phylum. Wolves are classified in the chordate phylum which does not include animals such as
insects and worms, but still includes other groups such as fish and birds. As the classification of the grey
wolf continues to be narrowed down, the ranks become more specific and the number of members in
each taxon becomes fewer. Within the family Canidae, the dogs, including foxes, jackals, and the
domestic dog. The Canis genus includes the grey wolf as well as the coyote and five other species.
Finally, the only kind of animal that remains at the species level is the grey wolf – Canus lupus.
Determining How Species Are Related
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The goal of modern classification is to assign species to taxa so that the classification reflects both
morphological similarities among organisms as well as hypothesis about their phylogeny (evolutionary
history).
If 2 species share much of the same evolutionary history, it means that have a fairly recent common ancestor.
The more a species shares its evolutionary history with another, the more closely related they are thought to
be.
ANCESTOR: is an organism from which other groups of organisms are descended.
o For example) The animals in the family Canidae (wolves, coyotes, jackals, foxes, and domestic dogs).
Members of this family have common characteristics such as 5 toes on the front feet and 4 toes on
the back feet; they are not able to retract their claws; they also have elongated snouts. And, in
terms of phylogeny, there is DNA evidence that they share a common ancestor.
Evidence of Relationships Among Species
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In modern taxonomy, there are 3 main types of evidence that are used to classify organisms: anatomical,
physiological, and DNA. The evidence is then used to hypothesize about evolutionary history and how closely
related different species are.
Example) Is the giant panda more closely related to bears or raccoons???? (answer: bears)
Anatomical Evidence of Relationships
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Studying morphology (referring to body size, shape and other physical features of an organism) helps
scientists determine evolutionary relationships among species.
ANATOMY is a branch of biology that deals with the structure and form, including internal systems.
For example) Dinosaurs and birds are more closely related than dinosaurs and reptiles. Many anatomical
structures were similar in dinosaurs and birds: both have bones with large hollow spaces (reptiles have
dense bones); the structure of a dinosaurs hip, leg, wrist, and shoulder bones is similar to that of a bird;
dinosaurs were found to have feathers.
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For example) The bones of a whale flipper, bat wing, horse leg, and human arm are all similar in overall
arrangement, but over millions of years, the size and the proportions of the bones have modified for
different purposes (swimming, flying, running, and grasping).
Physiological Evidence of Relationships
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PHYSIOLOGY is the branch of biology dealing with the physical and chemical functions of organisms,
including internal processes. It is the study of how organisms work.
Physiology studies include the proteins that organisms make. An organism’s proteins (whether as an
enzyme, or as part of cells, and tissues) are determined by its genes (since genes are coded instructions for
making proteins).
By comparing proteins among different species, the degree of genetic similarity can be determined.
For example) It was thought that the guinea pig and mouse were closely related. They were both classified
in the order Rodentia (the rodents). However, after studying several proteins (including insulin) it was
found that guinea pigs (especially their insulin) are very different from mice and that they needed to be
classified into a taxon of their own.
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DNA Evidence of Relationships
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For example) Based on analysis of DNA, scientists hypothesize that animals and fungi are more closely
related to each other than plants and fungi.
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Genes are sections of DNA made of long chains of molecules called nucleotides.
New DNA evidence has meant that prior classifications based on morphological, physiological, or other
evidence have been dramatically restructured.
For example) Canada’s only vulture, the turkey vulture, appears similar to vultures from Asia and Africa.
However, DNA indicates the turkey vulture may be more closely related to the stork, which are large
wading birds.
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Phylogenetic Trees
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PHYLOGENETIC TREE is a branching diagram used to show the evolutionary relationships among
species.
They are used to represent a hypothesis about the evolutionary relationships among groups of organisms.
It is like a family tree – the roots or the base of the phylogenetic tree represents the oldest ancestral
species. The upper ends of the branches represent present-day species that are related to the ancestral
species. Forks in each branch represent the points in the past at which an ancestral species split (or
evolved, or changed over time) to become 2 new species.
For example) A phylogenetic tree for the order carnivora
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New species that evolve from a common ancestor have some characteristics in common with the common
ancestor, as well as new features.
Biologists use these new features to define each family level of classification on the tree.
For example) Members of the family Bovidae (cows and antelopes) are artiodactyls that have the
anatomical feature of horns. Members of the family Cervidae (deer) are artiodactyls that have the
anatomical features of antlers. There are about 110 species of Bovidae and 40 species of Cervidae. Smaller
differences help distinguish one genus from another. For example, the family Cervidae includes 16 genera.
The genus Cervus includes deer with highly branched antlers, while animals in the genus Rangifer are deer
with broad, palmate antlers (having the shape of a hand).
For example) A phylogenetic tree for the reptile family.
KINGDOMS AND DOMAINS
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Even though all of the millions of species on Earth share certain fundamental similarities (such as being
made of cells and having DNA), there are various structural diversities.
STRUCTURAL DIVERSITY is diversity that is based on variety of both external and internal structural
forms in living things. This includes internal cell structure to body morphology.
The Six Kingdoms
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Always keep in mind the following:
o There are 2 main cell types that are significant for classification at the upper ranks, such as
kingdoms.
o The study of cell types and genes has led scientists to add a rank higher than kingdom – the domain.
o It is important to understand how biologists think domains and kingdoms are connected.
Originally, there were only thought to be 2 kingdoms for classifying organisms –plants and animals.
Now, the 6 Kingdoms are:
o Animals, Plants, Fungi, Protists, Bacteria, and Archaea (single-celled mirco-organisms)
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Two Major Cell Types
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If an organism is made up of one cell only, it is called a single-celled or unicellular organism.
If an organism is made up of more than one cell, it is called multicellular.
There are 2 main types of cells: Prokaryotic cells and Eukaryotic cells.
o PROKARYOTIC CELLS: is a small, simple cell that does not have a membrane-bound nucleus.
For example) Bacterial cell. It is the most ancient cell type. The name prokaryotic means “before
the nucleus”.
o EUKARYOTIC CELLS: is a larger, complex type of cell that does have a membrane bound-nucleus.
It has a complex internal structure, and is approximately 1000 times larger than prokaryotic cells.
The name eukaryotic means “true nucleus”.
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Comparing Prokaryotic Cells and Eukaryotic Cell Structures
The Three Domains
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As scientists continued to analyze organisms in the kingdoms Bacteria and Archaea, the category of domain
was added to the classification system. Scientists found that the differences between these two groups at the
genetic and cellular levels were so great that each group was elevated to a rank higher than kingdom –
domain. So, Bacteria and Archaea are two of the three domains.
Due to the reclassifying of these kingdoms as domains, biologists reclassified the remaining kingdoms in a
domain of their own, Eukarya. This makes sense since the other four kingdoms represent all the organisms
with eukaryotic cells.
Organisms in the two prokaryotic domains are unicellular, whereas unicellular and multicellular organisms
occur in the Eukarya.
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Dichotomous Keys
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A DICHOTOMOUS KEY is a system of narrowing down the identification of a specimen, one step at a
time. It is an identification solution that uses many 2-part choices to narrow down the solution. For
example) Red or Not Red.
When creating a dichotomous key for classifying species, you can use characteristics such as size, colour,
number of leaves or petals, branching patterns, etc.
However, if you are creating a dichotomous key for classifying organisms based on their kingdom, you need
to focus on things such as cell type, cell structure, methods of reproduction, and how the organism obtains
nutrients.
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Using a Dichotomous Key: See Page 27, Table 1.4: Dichotomous Key – Frogs and Toads
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Main Characteristics of Kingdoms
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Remember that prokaryotic cells and eukaryotic cells differ based on size, the presence of a nucleus, and
internal complexity.
Another cell-level distinction is the cell wall (a tough structure that surrounds most cells). Cell walls are
absent in animals.
With respect to nutrition, AUTOTROPHS are organisms that obtain energy by making its own food,
usually using sunlight.
A HETEROTROPH is an organism that cannot make its own food and must get its nutrients and energy
from consuming other organisms or autotrophs.
Asexual reproduction can be found in all kingdoms. However, sexual reproduction (in which genetic
material from2 parents combine to form offspring with a unique combination of genes) is a train that only
occurs in the Eukarya.
Characteristics That Differentiate the Six Kingdoms
(It is all the information needed to make a dichotomous key that can assign any species to its kingdom)
Domain
Bacteria
Archaea
Kingdom
Example
Bacteria
Straphylococcus
Cell Type
Number of
Cells
Cell Wall
Material
Prokaryote
Unicellular
Archaea
Sulfolobus
archaea
Prokaryote
Unicellular
Peptidoglycan
Nutrition
Autotrophs and
heterotrophs
Not
peptidoglycan;
occasionally
there is no cell
wall
Autotrophs and
heterotrophs
Primary
Means of
Reproduction
Asexual
Asexual
Eukarya
Protista
Amoeba
Plantae
Maple Tree
Fungi
Mushroom
Animalia
Rabbit
Eukaryote
Unicellular &
Multicellular
Cellulose in
some,
occasionally
there is no
cell wall
Autotrophs
and
heterotrophs
Asexual and
sexual
Eukaryote
Multicellular
Eukaryote
Multicellular
Cellulose
Eukaryote
Mostly
Multicullular
Chitin
Autotrophs
Heterotrophs
Heterotrophs
Sexual
Sexual
Sexual
No cell wall
CLASSIFYING TYPES OF BIODIVERSITY
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SPECIES DIVERSITY is the variety and abundance of species in a given area.
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GENETIC DIVERSITY is the variety of heritable characteristics (genes) in a population of interbreeding
individuals. It is evident in the variety of inherited traits within a species. For example) The patterns on
the tails of humpback whales.
o Genetic diversity is very important in disease resistance. Populations that lack genetic diversity are
more susceptible to disease than those with high diversity. This is because if none of the
individuals in a species have the ability to survive the disease, the entire population could be
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eliminated. For example) The lack of genetic diversity of the Tasmanian devil has been a key factor
in making it an endangered species. They suffer from a contagious cancer that causes tumours on
the face and mouth.
Genetic diversity allows populations and species to survive changing environmental conditions (ie:
change in resource availability, climate change, a change in a predator population, or an
introduction of a non-native species).
Scientists can help conserve a species that has low diversity. For example) The Florida panthers
became endangered due to a lack of genetic diversity. So, scientists introduced 8 female panthers
taken from a population of panthers in Texas. It was successful at greatly increasing the population
in Florida.
GENES are the genetic material that controls the expression and inheritance of traits (ie: the
amount of sugar in blueberries, pattern arrangements in ladybeetles, and human height). The
variation among individuals in a population is largely a result of the difference in their genes.
Genetic diversity within a population is known as the GENE POOL. It is the sum of all the versions
of all the genes in a POPULATION (a group of individuals of the same species in a specific area at a
specific time). The genetic diversity within a species is typically greater than that within a
population.
ECOSYSTEM DIVERSITY is the variety of ecosystems in the biosphere. It is the rich diversity of
ecosystems found on Earth, each of which contains many species.
o It is the largest scale of diversity. It is the diversity of the ecosystems in the biosphere.
o Ecosystems are made up of abiotic (non-living) factors and biotic (living) factors. Biotic factors
include interacting populations of species. Abiotic factors include altitude, latitude, geology, soil
nutrients, climate, and light levels.
o Due to the diversity of relationships among organisms and the variety of abiotic factors, Earth’s
surface is highly varied physically and chemically – which makes its ecosystem diversity very rich.
o Ecosystem Services are the benefits experiences by organisms, including humans, which are
provided by sustainable ecosystems. For example) Forests take up carbon dioxide and maintain
soil fertility.
o Wetlands provide several important ecosystem services (storing water which reduces the risk of
floods; filtering water which removes pollutants; and providing habitat for commercially important
species of fish and shellfish).
o Some examples of the World’s Ecosystem Services:
Ecosystem Service
Water supply
Pollination
Recreation
Ecological control
Example
Irrigation, water for industry
Pollination of crops such as apples, blueberries, and clover
Ecotourism
Pest population regulation
Ecosystem Function and Species Diversity
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Ecosystems with greater species diversity are more likely to provide important service reliability. They
also provide more resilience.
o RESILIENCE is the ability of an ecosystem to remain functional and stable in the presence of
disturbances to its parts. It is the ability of an ecosystem to maintain equilibrium, or balance.
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Ecosystem Services and Human Actions
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Sometimes humans alter an ecosystem to enhance the services of the ecosystem. For example) Wildlife
officials may add more fish to a lake to provide for recreational fishing.
However, the introduction of non-native species can lead to the reduction of a population of native
organisms.
For example) When non-native trout were introduced into California’s mountain lakes, it led to a drop in
the population of several amphibians and aquatic insects. The trout consumed aquatic insects in the larval
stage. Therefore, amphibians and other fish lost their food source. As well, birds and bats that lived near
the lake lost their food source.
For example) In Ontario, smallmouth bass were added to enhance recreational fishing. However, this led
to a change in the lake ecology. It also led to the loss of some native fish species (such as stickleback and
dace). Overall, this led to a decline in species diversity and a loss of complexity of the ecosystem.
For example) When bass were introduced to lakes with lake trout, the situation is worse. The trout are the
top predators. However, with the reduction in small fished caused by the introduction of bass, affected the
population size of the trout.
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Examples of Ways to Use Classification:
Books in Library:
Food in a grocery store:
Your dresser:
Grade book:
Cd's in a store:
Clothes in a store:
Laundry:
Coin collection:
Baseball cards:
Cars in a car lot:
Food on a menu:
Fiction / Non-fiction; Childrens' Department; Alphabetical,
Dewey Decimal
Frozen, Fresh, Canned, Meat, Dairy
Socks, Underwear, T-shirts
Classes, Grading, Periods, Assignments
Kind of Music, Alphabetical by name
Mens, Womens, Kids, Pants, shirts, dresses, Sizes
Whites, Darks, Delicates
Country, Denomination
Teams, Rookies, Stars
New, Used; rucks, SUV's, Compact, Sedans, Vans, Luxury
Appetizers, Soups, Salads, Entrees, A la carte, Deserts
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