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Biology II:
Fundamentals of evolution,
systematics and diversity of life
ESNRM 11209
Sandun J Perera, PhD
Department of Natural Resources
Sabaragamuwa University of Sri Lanka
Topic 3
Biosystematics
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Biosystematics

Biosystematics → Bio(logical) Systematics

Biosystematics: the systematic study of the diversity of
life on the planet earth, both past and present, and the
relationships among living things through time.
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Biosystematics


Systematics is fundamental to biology;

because it is the foundation for all studies of organisms,

that shows how any organism relates to other living organisms
Systematics is also of major importance in understanding
conservation;

because it attempts to explain the earth's biodiversity, and

used in prioritising taxa for conservation e.g. Red Listing
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Biosystematics

The topic will be discussed under three main sub-topics;

1. Taxonomy (= Biosystematics)

The holistic practice of describing, identifying, classifying, and naming of
organisms systematically.

And then we discuss the two key processes in taxonomy (among the
above list of processes) in two separate sub topics;

2. Classification


Placing organisms within groups, that show their relationships to other
organisms
3. Nomenclature

The system of naming organisms systematically
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Biosystematics

Hence;

The term “biosystematics" is sometimes used
synonymously with "taxonomy”


which is correct
But, the term “biosystematics" is sometimes confused
with "scientific/biological classification”

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which is wrong
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Taxonomy
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Taxonomy

Meaning of the term “taxonomy” -
science and the practice of classification
In Greek; τάξις → taxis = “order” + νόμος → nomos = “law” or “science”

But it includes the holistic practice of describing, identifying,
classifying, and naming of organisms systematically

Taxonomy is the primary tool in understanding organisms,

as nothing about an organism's relationships with other living things can
be understood without it first being properly studied and described in
sufficient detail to identify and classify it correctly
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Taxonomy

In taxonomy organisms are grouped according to phylogenetic
relationships following a hierarchic pattern of ancestor descendant
sequence.

Taxonomic units / levels

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known as taxa (singular taxon)
are hierarchical in structure

Domain

Kingdom

Phylum (for animals) or Division (for plants)

Class; Order; Family; Genus; Species.
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Taxonomy

Basis of taxonomy is common ancestry.

The common ancestry is determined by features organisms have in
common.

Two species that have a common ancestor (shown by a feature
shared in both species),
which they do not share with a third species,
are considered to be more closely related to each other than to the
third;
so grouped into a single genus.

e.g. The American black bear and the Polar bear, against the Panda
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Two main approaches in taxonomy/systematics

Phenetic systematics


Phenetic systematics involves classification by using the
morphology and physiology of the organisms.
Phylogenetic (Cladistic) systematics

Phylogenetic systematics uses evolutionarily novel
characteristics, to calssify organisms and their relationships
through time.

Today, phyologenetic systematists generally make extensive use
of molecular genetics and computer programs to study
organisms.
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Taxonomic groupings

A fundamental taxonomic grouping;

two fundamental groups of organisms were recognized in 1937

Prokaryotes


Life form in which DNA is not organised within a cell nucleus.
Eukaryotes

Organisms possessing an organised nucleus enclosed by a double
nuclear membrane.

This grouping was first proposed by Chatton (1937) as two
Empires: Prokaryota and Eukaryota

They are known today as Domains: Prokarya and Eukarya
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Édouard Chatton (1883 – 1947)
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Prokaryotic vs. Eukaryotic Cells
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Classification
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Classification

Organisms are not evolved on earth for humans to classify and
put in to groups



The evolution is an ongoing process which never ends
The classification systems are artificial and keeps changing

more and more refined methods are employed in identification and
characterization of species

established relationships between species change, as a result of
changes in calssification

e. g. numbers of established species in known taxa have increased
considerably with the use of DNA for species characterissation

8,600 bird species in 1956 have increased to 9,956 (~10,000) by 2016
Let’s forget about the species and have a look at the history of
classification in Domain & Kingdoms of organisms
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Two kingdom classification

Two kingdoms of living things:
Animalia for animals and Vegetabilia for plants
(Carolus Linnaeus, 1735: Systema Natuare)



Linnaeus also treated minerals, as a third kingdom, Mineralia
When single-celled organisms were first discovered, they were split
between the two kingdoms:

Mobile forms in the Animal kingdom (phylum Protozoa)

Algae and Bacteria in Plant Kingdom (divisions Thallophyta or Protophyta).
However, several forms were hard to place, or were placed in
different kingdoms by different authors

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Ernst Haeckel suggested creating a third kingdom Protista for them
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Carolus (Carl) Linnaeus (1707 – 1778)
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Three & Four kingdom classifications

Three-kingdom system:

Plantae, Protista, Animalia (Haeckel, 1866: Generelle Morphologie der
Organismen)

In the meantime Chatton identified two empires

Going along the same lines, Herbert Copeland gave the prokaryotes
a separate kingdom, originally called Mychota but later referred to as
Monera.

Four-kingdom system:

Monera, Protista, Plantae, Animalia (Copeland, 1956)

Here, he placed

All prokaryotes in to Kingdom Monera

And, all eukaryotes other than animals and plants in the kingdom Protista
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Ernst Heinrich Philipp August Haeckel (1834 – 1919)
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Herbert Faulkner Copeland (1902 – 1968)
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Five kingdom classification

Robert Whittaker recognized an additional kingdom for the Fungi.

Five-kingdom system:


Monera, Protista, Fungi, Plantae, Animalia (Whittaker, 1969)
It is based mainly on differences in nutrition:

Plantae - mostly multicellular autotrops.

Animalia – multicellular heterotrops.

Fungi – multicellular saprotrops.

Protista and Monera - unicellular organisms and simple cellular colonies
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Robert Harding Whittaker (1920–1980)
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Six kingdom classification

In early 1980 the emphasis on phylogeny caused redefining of
the kingdoms.

Based on r-RNA studies Carl Woese divided the prokaryotes
into two kingdoms, called Eubacteria and Archaebacteria.

Six-kingdom system:

Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia
(Woese, 1977)

This have become the standard in many works.
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Carl Richard Woese (1928 – 2012)
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Six kingdom classification

Most Taxonomist use the six -kingdom system today

It groups organisms that have similar characteristics in


major cellular structure

methods of obtaining nutrients

Metabolism
Viruses are not included in any kingdom - due to their
non-living characteristics (they are not cells)
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Summary:
History of classification systems
Linnaeus
1735
2 kingdoms
Haeckel
Chatton
1866
1937
3 kingdoms 2 empires
(not treated)
Protista
Vegetabilia
Plantae
Animalia
Animalia
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Copeland Whittaker Woese et al.
1956
1969
1977
4 kingdoms 5 kingdoms 6 kingdoms
Eubacteria
Prokaryota Monera
Monera
Archaebacteria
Protista
Protista
Protista
Fungi
Fungi
Eukaryota
Plantae
Plantae
Plantae
Animalia
Animalia
Animalia
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Woese et al.
1990
3 domains
Bacteria
Archaea
Eukarya
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Carl Richard Woese (1928 – 2012)
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Three-domain system (Woese et al., 1990)

Through the development of molecular biology, It was
found that there has been a common ancestor of all
organisms.

This was found by comparing 16 S ribosomal RNA
sequences, which do not recombined during
reproduction

The PHYLOGENTIC TREE (FAMILY TREE) drawn from
this data show that living things SEEM to fall naturally
into Three Broad Groups, or DOMAINS
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Three-domain system (Woese et al., 1990)
EUBACTERIA
ARCHAEBACTERIA
PROTISTA
PLANTAE
FUNGI
ANIMALIA
SIX KINGDOMS
Relationships
between today’s
organisms
Where modern kingdoms
diverged from a common
ancestor
BACTERIA
ARCHAEA
COMMON
ANCESTOR
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EUKARYA
THREE DOMAINS
From common ancestor of all organisms. The most
ancient lineages are at the bottom and the most recent are
at the top on a vertical time scale
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Three-domain system (Woese et al., 1990)
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Three-domain system (Woese et al., 1990)



DOMAIN ARCHAEA

Kingdom Archaebacteria (ancient bacteria)

the chemosynthetic OR heterotrophic bacteria
DOMAIN BACTERIA

Kingdom Eubacteria (true bacteria)

the disease-causing (heterotrophic) bacteria.
DOMAIN EUKARYA


All complex organisms - Protists, Fungi, Plants and Animals
Archea and Eukariya are more closer and evolved from a common
ancestor, where Domain Archea is the most primitive and Domain
Eucariya is the least primitive
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DOMAIN ARCHIA (KINGDOM ARCHAEBACTERIA)

Typical PROKARYOTIC cell structure
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DOMAIN ARCHIA (KINGDOM ARCHAEBACTERIA)

UNICELLULAR, PROKARYOTES

Some are AUTOTROPHIC, producing food by CHEMOSYNTHESIS

Most are HETEROTROPHIC

They may have directly descended from, and looks very similar to the
“first organisms on earth”

Archae = "ANCIENT“ in Greek.

Distinctive features;

A single thick, homogeneous cell wall

Biochemical and Genetic Properties that Differ from all other kinds of Life.
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DOMAIN ARCHIA (KINGDOM ARCHAEBACTERIA)


Archaebacteria live in anaerobic and harsh environments

Intestines of mammals.

Sulfurous hot springs.

Very salty lakes.
They multiply by

Budding

prokaryotic binary fission (single cell divides into 2)

fragmentation (single cell divides into more)
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DOMAIN BACTERIA (KINGDOM EUBACTERIA)

More evolved PROKARYOTIC cell structure
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DOMAIN BACTERIA (KINGDOM EUBACTERIA)

UNICELLULAR, PROKARYOTES.

Both AUTOTROPHS and HETEROTROPHS

Includes all the disease-causing bacteria such as tooth decay or food
poisoning

Have a more evolved cellular structure

A cell wall, plasma membrane, nucleoid region, ribosome, flagella and pilli,
capsule and slime layer, and an endospore to survive high temperatures
and extreme conditions

Reproduce by prokaryotic binary fission (single cell divides into 2)

They do have ways to recombine genes, allowing evolution to occur.

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Bacterial Conjugation – DNA transfer between 2 bacterial cells, through a
conjugation tube
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DOMAIN BACTERIA (KINGDOM EUBACTERIA)

Bacterial Conjugation
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DOMAIN EUKARIA

Organised EUKARYOTIC cell structure
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DOMAIN EUKARIA


Distinctive features of Eukaryotes;

Organised and membrane bound (true) nuclei with linear
chromosomes

Membranous organelles

Cytosceleton
Four kingdoms;

Protista, Fungi, Plantae and Animalia.

The kingdoms Fungi, Plantae and Animalia shares a common
ancestor
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KINGDOM PROTISTA (≡ PROTOCTISTA)

EUKARYOTES

UNICELLULAR and MULTICELLULAR

Both AUTOTROPHS and HETEROTROPHS

Grouping of diverse eukaryotic organisms that are
not animals, plants or fungi.

They do not form a natural group (or clade), but are often grouped together
for convenience. In cladistic systems, these refers to a paraphyletic group
which spans the entire eukaryotic tree of life.

They include;

Protozoa - the unicellular "animal-like (heterotrophic/parasitic) Protists

Protophyta - the "plant-like" (autotrophic) Protists (mostly unicellular algae)

Molds - the "fungus-like" (saprophytic) Protists (slime molds and water molds).
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KINGDOM FUNGI

EUKARYOTES

Most are MULTICELLULAR

SAPROTROPHIC (ABSORPTIVE HETEROTROPHIC)

Obtain their nutrients by releasing digestive enzymes into the food source.
Then absorb the digested food.

naturally act either as DECOMPOSERS or PARASITES

Cell walls contain a material called Chitin (A polysaccharide)

Posses a unique cellular structure

Kingdom Fungi includes Molds, Mildews, Mushrooms and Yeast
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KINGDOM PLANTAE

EUKARYOTES

MULTICELLULAR

AUTOTROPHS - Carry out Photosynthesis.

Cell walls, contain Cellulose (A polysaccharide).

Plant cells are specialized for different functions, such as
photosynthesis, transport, support, etc.

Kingdom Plantae includes Mosses, Ferns, Cone-bearing plants
(GYMNOSPERMS), and Flowering plants (ANGIOSPERMS)
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KINGDOM ANIMALIA

EUKARYOTES

MULTICELLULAR

HETEROTROPHIC

Do not have cell walls.

Most members can move from place to place, but some are
permanently attached to a surfaces (e.g. Sponges and Barnacles)

Kingdom Animalia includes Sponges, Jellyfish, Worms, Insects, Sea
stars, Fish, Amphibians, Reptiles, Birds and Mammals, including
human
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Summary: Six Kingdoms of life
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Nomenclature
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Nomenclature

Once a new species is recognised, it is named according to a
universal system of scientific nomenclature: Process of Description

All identified species in the world, including the extinct fossil species,
have a scientific name

Name consists of a generic name followed by a specific epithet.

generic name starts with a capital letter

species name (epithet) starts with a simple letter

Binomial system of nomenclature – Carolus Linnaeus, 1758

It is Latinized and printed in italics or underlined


Latin was considered the language of educated during medieval period
Before Linnaeus, scientific names had several words: polynomials
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Nomenclature

Today the taxonomic nomenclature is been controlled by
voluntary application of internationally agreed codes to
preserve its uniformity

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International codes of nomenclature for animals, plants & bacteria
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ICZN – International Code of Zoological Nomenclature

For name of a faunal species to be considered valid the species
name (epithet) has to be introduced with the generic name in
Latinised form.

For this, a statement is needed proposing a latinised binomial
name for newly recognized species, along with a description of
how it differs from other related species.

This description has to be published in printed form
accompanied by a specimen designated as the type specimen.
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ICZN – International Code of Zoological Nomenclature

In case if a species has been given two names by two
different people, it will be corrected by giving priority to the
oldest name, once it is detected.


Junior synonym becomes invalid
Name of the original author, and the year of publication of the
original name is mentioned when a species name is written
formally;

Elephas maximus Linnaeus, 1758

Gona sinhalaya Deraniyagala, 1938
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ICZN – International Code of Zoological Nomenclature

When there is a taxonomic revision for the genus name, the original
author & the year of publication is given in brackets following the
scientific name


e.g. “Newgenus” maximus (Linnaeus, 1758)
Trinomens are given when there are different sub species

the sub population first described is designated by tautonymy (it is called
the nominate subspecies)

e.g. Trachypithecus vetulus vetulus Erxlenben, 1977
(Southern lowland wetzone purple-faced langur)

other sub species get different third names.

e.g. Trachypithecus vetulus monticola Erxlenben, 1977.
(Montane purple-faced langur / Bear Monkey)
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ICBN – International Code of Botanical Nomenclature

The code governs the scientific names of both green plants and fungi

It is similar to ICZN except for few features

Double citation is practiced when there is a taxonomic revision for a taxa


Scentless mayweed – named by Linnaeus in 1755 as Matricaria inodora

revised and placed in a different genus by Schultz (Sch-Bip)

its present name is Tripleurospermum inodora (L.) Sch-Bip, 1755

note the standard acronyms for author names: botanical author abbreviations
Tautonyms are not permitted in botanical names
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In addition to ICZN &
ICBN, international
codes are there
for naming
bacteria and
viruses too.
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Type specimens

Type specimen = the specimen to which the original name is attached to, and
referred to in its original description

Holotype is the specimen which demonstrate the characters on which the new
name is based

When the author select one specimen as the holotype from a group of type
specimens, others are known as Paratypes

The entire group of specimens, the author refer when describing a species are
Syntypes

When there is a dispute on the name designated to a species, the name that best
fits the type specimen will be accepted

Therefore, it is very important to well preserve the type specimens, with a clear
label, and placed permanently in an internationally reputed place such as a natural
history museum
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The British Museum of Natural History, London
Any many more such museums worldwide
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Type specimens
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QUIZ
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