Transcript Unit 2 – Diversity of Life - - - - - Millions of species (2-4.5 million) exist on planet earth (huge amount of biodiversity). Classifying all these species.

Unit 2 – Diversity of Life
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Millions of species (2-4.5 million) exist on planet
earth (huge amount of biodiversity).
Classifying all these species helps make sense of
all the biodiversity.
Many species have become extinct in the past.
Many existing species are becoming extinct
before we even know they exist! Some of these
species could be important for our species in
terms of medical or ecological significance.
Taxonomy – the science of naming and
classifying organisms
Taxon – a group of organisms in a classification
system
Binomial Nomenclature
Two-word standard naming system for all
known organisms
Based on the dead language latin – dead
because it is not spoken any more and thus
doesn’t change over time
Two part name – genus + species: ex. Homo
sapiens, Canis lupis
Universal over all languages so species
identification cannot be mistaken from language
to language.
a scientific (biological) name can help
distinguish common name confusion.
What is a Gopher?
In Saskatchewan,
a gopher is this:
Species name: Urocitellus
richardsonii
In Florida, a
gopher is this:
Species name: Gopherus
polyphemus
Linnaeus
Carl von Linne (Carolus Linnaeus – he “Latinized”
his name) – Swedish botanist: developed the
Linnaean system of classification (binomial
nomenclature)
His system of naming organisms is still used today
3 rules used:
Genus – always capitalized, ex: Canis
Species – always not capitalized ex: lupis
Entire species name (genus and species) is
underlined (if handwritten) or italicized (if typed)
Underlined (or italicized) so that the scientific name
stand out from rest of the text present
7 Levels of Classification (Taxons)
Kingdom – ex: Animals
Phylum (animals) / Division (plants) - ex:
Chordata
Class – ex: Mammalia
Order – ex: Primates
Family – ex: Hominidae
Genus – ex: Homo
Species – ex: sapiens
“King Phillip Came Over For Graduation
Speeches”
Questions 1-3, page 521
1. What is binomial nomenclature?
- It is a system that gives every species a unique twopart name that identifies it. The first part is the
genus, and the second part is the species
descriptor.
2. Name each taxon in the Linnaean system of
classification, from most general to most specific.
- kingdom, phylum, class, order, family, genus, species
3. What are some limitations of the Linnaean
classification system?
- It only accounts for physical and structural similarities
between organisms, which can be the result of
convergent evolution and therefore not indicative of
relatedness.
Questions 4-5, p521
4. How is a scientific name similar to an address
that includes city and state?
- A state (or province) has many cities as a genus has
many species. Like species descriptors, city
names cannot be used alone because the same
city names can occur in different states (or
provinces), as with Portland (Maine and Oregon).
5. Which two species are more closely related:
Ursus maritimus, Ursus americanus, or Bufo
americanus?
- Ursus maritimus (polar bears) and Ursus
americanus (black bear) are most closely related;
they belong to the same genus.
Question 6, p521
6. During his voyage, Charles Darwin
collected thousands to organisms, which
he classified using the Linnaean
classification system. How did this
system help him share his findings with
other naturalists?
- Others could understand the relationships
between organisms, such as Darwin’s
finches, and there was uniformity in temrs
of language. Had he used common
names alone, they would have required
translation into many languages.
Dichotomous Keys
Dichotomous keys are used to identify
objects or organisms that have already
been described by another scientist.
As its name implies (di- means "two"), a
dichotomous key is made up of paired
statements.
Each pair of statements divides the
objects to be classified into two categories.
This means that each object must fit into
one category or the other, but not both.
Sample Dichotomous Key:
# of Kingdoms?
- 1753: Two kingdoms – Animalia & Plantae
- 1866: Three kingdoms – Animalia, Plantae &
Protista
- 1938: Four kingdoms - Animalia, Plantae,
Protista, & Monera
- 1959: Five kingdoms - Animalia, Plantae,
Protista, Monera & Fungi
- 1977: Six Kingdoms - Animalia, Plantae,
Protista, Bacteria, Fungi, & Archaea
History of the Kingdom System
3 Domains Tree of Life
3 Domains of Life
1. Domain – Bacteria
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- One kingdom: Bacteria
Single celled prokaryotes (lack a nucleus and
organelles)
One of the largest group of organisms on earth
2. Domain – Archaea
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One Kingdom: Archaea
Single celled prokaryotes (lack a nucleus and
organelles)
Live in extreme environments: deep sea vents, hot
geysers, Antarctic waters, salty lakes, acidic
environments
3. Domain – Eukarya
Four kingdoms:
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Plantae
Protista
Fungi
Animalia
Single-celled (protista) or multicellular (fungi,
plantae & animalia)
Eukaryotic: cells possess a nucleus and organelles
Questions 1-2, page 535
1. Why is classification of life considered a
work in progress?
- Scientists are always finding more information
about organisms that forces a reexamination of classification schemes.
2. What kingdoms are included in each of
the three domains in the modern tree of
life?
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Bacteria: bacteria
Archaea: archaea
Eukarya: protista, fungi, plantae, animalia
Questions 3-4, page 535
3. If you come cross across an unusual single-celled organism,
what parts of the cell would you study to classify it into one of
the three domains?
- Nucleus (or lack thereof) and cell wall
4. Explain, using the traditional definition of species, why it is
difficult to classify some bacteria and archaea at the species
level.
A species can be defined as an interbreeding group of
organisms that produce fertile offspring. But bacteria and
archaea do not breed to produce offspring; they reproduce
by binary fission. In reproduction, as it is generally defined,
parents also pass genetic material to their offspring.
However, many bacteria and archaea can take up genetic
material from their environment – a transfer of genes
outside of typical reproduction that does not occur in
eukaryotes.
Question 5, p535
5. History of Life – The Archaea lineage
may include the first life on Earth, which
began under much different
environmental conditions from those
present today. What characteristics of
archaea help support this statement?
- Archaea exist in extreme environments that
are similar to those of early Earth.