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UNIT 1: Diversity of Living Things
Chapter 1: Classifying Life’s Diversity
How do scientists classify life on Earth?
Chapter 2: Diversity: From Simple to Complex
Chapter 3: Multicellular Diversity
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Chapter One: Classifying Life’s Diversity
The yeti crab (Kiwa hirsuta) is a species discovered during
the Census of Marine Life.
• Why was such a project created?
• Why might it be important?
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
1.1 Identifying, Naming, and Classifying Species
Scientists identify, define, and name species of organisms.
Why is this important?
• Farmers and gardeners need to separate weeds from crops.
• Doctors must correctly identify infectious organisms
before treatment.
• Edible and medicinal plants must be correctly identified
before use.
• What other examples can you think of?
How could scientists
determine if this pink iguana is a
different species from others on
the island?
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Identifying Species: Using Species Concepts
Scientists require a working definition of the concept of a
species. Three are commonly used:
• Biological Species Concept
• Morphological Species Concept
• Phylogenetic Species Concept
morphology: the branch of
biology that deals with the
structure or form of organisms]
phylogeny: the evolutionary
history of a species
Continued…
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Identifying Species: Using Species Concepts
Continued…
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Identifying Species: Using Species Concepts
Continued…
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Identifying Species: Using Species Concepts
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Standard Names for Species:
Binomial Nomenclature
Taxonomy is the identification, classification, and naming
of species.
Binomial nomenclature refers to a two-part naming
system. An organism’s scientific or species name has two
parts:
• The first part, the genus name, identifies the group of
closely related species to which the species belongs.
• The second part is the species name.
Continued…
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Standard Names for Species:
Binomial Nomenclature
The Binomial nomenclature system was first developed
by Carolus Linnaeus.
Scientists around the world
refer to this animal as Marmota
(genus) monax (species).
What are some of its
local (common) names?
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Classifying Species
Scientists use the three species concepts to determine
which organisms make up a species. Then they arrange the
different species in related groups.
Classification is the grouping of organisms based on a set
of criteria that helps to organize and indicate evolutionary
relationships.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Hierarchical Classification
A hierarchy arranges items above, below, or at the same level
as other items in the group.
Hierarchical classification classifies organisms by arranging
species based on categories from most general to most
specific. This is known as a nested system.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Taxonomic Categories Used To
Classify Organisms
Taxonomic categories are used to classify organisms that
have been identified. The categories or groupings are
arranged in a hierarchy.
Each level or category is known as the rank. The particular
classification of an organism at each rank level is called
the taxon (pl. taxa).
There are eight ranks.
Domain is the most general,
containing the most species.
The species rank is specific
to one species.
Continued…
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1
Taxonomic Categories Used To
Classify Organisms
Write the rank levels in order from
most general to most specific.
Write the full taxonomic
classification of the grey wolf.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.1 Review
Section 1.1
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.2
1.2 Determining How Species Are Related
Modern classification uses morphological similarities and
evolutionary history to assign a species to taxa.
Hypotheses about the evolutionary history and
relationships among different species are made based on
three types of evidence:
• anatomical
• physiological
• DNA
Continued…
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.2
Determining How Species Are Related
Species that have many anatomical, physiological, and
molecular (DNA) characteristics in common are thought to
share a common evolutionary ancestor.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.2
Anatomical Evidence of Relationships
Anatomy is the study of the structure and form of
organisms (including internal systems). It is a branch of
morphology and further helps scientists determine
evolutionary relationships among species.
These bone structures are similar even though the limbs look different. Over
millions of years, the limbs have changed to better suit swimming, flying,
running, or grasping, but the overall arrangement of bones and similarities
indicate a shared evolutionary history.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.2
Physiological Evidence of Relationships
Physiology deals with the physical and chemical functions
of organisms, including their biochemistry and internal
processes. Taxonomists use the data on the physical and
chemical functions of an organism to classify it.
Guinea pigs and mice were once both classified in the order
Rodentia. An analysis of proteins, including insulin, showed
that guinea pig insulin is very different from that of typical
rodents. Guinea pigs were reclassified into a taxon of their
own.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.2
DNA Evidence of Relationships
New technology has made it possible to conduct genetic
analysis and de-code the sequences of nucleotides in DNA.
DNA from different species can be compared to determine
relationships.
In some cases, new DNA evidence has meant that
classifications based on morphological, physiological, or
other evidence have to be restructured.
Fungi and plants are
superficially similar—they
do not move, and they
grow out of the ground.
However, DNA evidence
suggests that fungi are
more closely related to
animals than to plants.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.2
Phylogenetic Trees
A phylogenetic tree is a branching diagram used to show the
evolutionary relationships among species.
Study the
phylogenetic tree. To
which other organism is
Cervus elaphus most
closely related? At what
rank and taxon are they
related?
The animals shown
here are all part of the
order Artiodactyla.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.2
The Importance of Classification
Classification can assist in:
• the discovery of new drugs, hormones, and other medical
products
• tracing the transmission of disease and the development
and testing of possible treatments
• increasing crop yields and disease and pest resistance
• environmental conservation of organisms
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.2 Review
Section 1.2
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.3
1.3 Kingdoms and Domains
The second most general rank, kingdom, includes six different taxa.
There is incredible structural diversity (internal and external
forms) within the kingdoms even though species are grouped.
Advances in microscopy and molecular biology have increased the
number of kingdoms from two in the 1800s to six in 2010.
Classification at the kingdom level is based on general internal and
external similarities, but it begins with the two basic cell types on
Earth.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.3
Two Major Cell Types
There are two major cell types: prokaryotic and eukaryotic.
Which type of cell might have originated first,
prokaryotic or eukaryotic? Explain your answer.
What other differences can you observe?
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.3
The Three Domains and Dichotomous Keys
There are three domains:
• Bacteria
• Archaea
• Eukarya
Eukarya includes all species made up of eukaryotic cells (four
kingdoms). Both Bacteria and Archaea are prokaryotic
domains but are not grouped due to great cellular and genetic
(DNA) differences.
Continued…
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.3
The Three Domains and Dichotomous Keys
To classify an organism, scientists begin at the domain level
and work through many sequential questions with only two
possible answer choices to reach a genus/species level of
identification. This system is called a dichotomous key. Most
questions involve anatomical and structural analysis. In some
cases, only the kingdom taxon is required.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.3
Main Characteristics of Kingdoms
When classifying only to the kingdom rank, the following
characteristics can be used:
•
•
•
•
number of cells (unicellular or multicellular)
cell wall material (if present)
nutrition (autotroph or heterotroph)
primary means of reproduction (asexual or sexual)
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UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.3
Main Characteristics of Kingdoms
An autotroph captures energy from sunlight/abiotic
substances. A heterotroph obtains energy by consuming
other organisms.
Try to use the characteristics above to identify the
kingdom for each organism. Infer where necessary.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.3 Review
Section 1.3
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.4
1.4 Classifying Types of Biodiversity
Genetic diversity
There are three
important ways of
studying biodiversity.
Ecosystem diversity
Continued…
Species diversity
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.4
Classifying Types of Biodiversity
• Genetic diversity is the variety of heritable characteristics
(genes) in a population of interbreeding individuals.
• Species diversity is the variety and abundance of species
in a given area.
• Ecosystem diversity is the variety of ecosystems in the
biosphere.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.4
Genetic and Ecosystem Diversity
A gene pool is the sum of all the versions of all the genes in a
population. The larger the gene pool and genetic diversity, the
better the chances of species survival despite environmental
pressures or changes (diseases, for example).
On a much larger scale, ecosystem diversity refers to the
variety of ecosystems in all sizes from a plant to an entire
biome. The health and sustainability of the biosphere can be
measured by the richness of ecosystem diversity.
The population of Tasmanian devils
(Sarcophilis harrisii) has been severely
reduced by cancer. A lack of genetic
diversity made the animals vulnerable
to disease.
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.4
Ecosystem Services
Ecosystem services are the benefits experienced by species
(including humans) that are provided by sustainable
ecosystems. Examples of services include:
•
•
•
•
atmospheric gas supply
climate regulation
water supply
food production
•
•
•
•
raw materials
waste treatment
soil erosion control
nutrient recycling
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.4
Ecosystem Services and Human Activity
Ecosystems with greater species diversity are more likely to
provide important services reliably and are also more resilient
despite disturbances. Disturbances can include:
• non-native species invasion
• disease
• changes in abiotic factor concentrations
Human activity must not lower the species diversity of an
ecosystem and consequently lower its sustainability and
services.
Continued…
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.4
Ecosystem Services and Human Activity
UNIT 1 Chapter 1: Classifying Life’s Diversity
Section 1.4 Review
Section 1.4
UNIT 1 STSE Feature
DNA Bar Codes
Paul Hebert, a geneticist at the University of Guelph, in Ontario, is trying to gather cell samples
from all of the world’s organisms. With small pieces of tissue no larger than the head of a pin,
Hebert and his colleagues are working to assign DNA bar codes to every living species.
Hebert has shown that the segment of mitochondrial DNA, called cytochrome c oxidase I, or
COI, can be used as a diagnostic tool to tell animal species apart. The COI gene is easy to isolate
and allows for identification of an animal. A different gene would need to be used for plants. Just
like the Universal Product Codes (UPC) that appear on product packaging, the DNA segment
sequences could be stored in a master database that would allow for easy access to the material. A
hand scanner, when supplied with a small piece of tissue, such as a scale, a hair, or a feather, could
identify the species almost instantly.