Emp1003 biodiversity and classification

All organisms have different names in different
languages. Besides these so-called ‘common’ names
they also have one – in Latin - which is recognised all
over the world. This is known as the scientific name.
2Istitut tal-Agrikoltura

Taxonomy is that branch of biology dealing with the
identification and naming of organisms.
Aristotle (384-322 BC) apparently began
the discussion on taxonomy by attempting
to put ‘order’ in the environment around
him.
This is how Aristotle divided the objects around him and
started taking the first steps in classification
4Institute of Earth Systems

Taxonomy comes from the Greek taxis "arrangement"
and nomia "method“.
5
It is not simply the
naming of organisms
but refers to their
classification – the
names themselves
are derived from this
arrangement.
Institute of Earth Systems

Aristotle considered
that nature is ordered
from the lower to the
higher, ranging from
nonliving beings, to
plants and animals,
all the way to
humans.
These are the "steps
of nature,“.

Hardly any progress was made in
medieval times. In fact, there was
a lot of confusion between real
and mythical creatures.
7

The Renaissance
marked the beginning
of a new era that
would gradually bring
about a disctinction
between science and
superstition.

The discovery and
gradual exploration
of the New World
produced large
numbers of new
plants and animals
that needed naming,
describing and
classifying.

The old systems made it
difficult to study and
locate all these new
specimens within a
collection and often the
same plants or animals
were given different
names simply because
there were too many
species to keep track of.

A system was needed
that could group these
specimens together so
they could be found. In
the late 16th – early
17th century, a
systematic study of
animals started being
carried out.

The system concerned
familiar animals first
and then was
gradually extended
until it developed
enough to serve as
basis for classification.

John Ray (1627-1705) is
credited with working on a
concept of naming and
describing organisms.
13
He was an English naturalist
and botanist who contributed
significantly to the
identification of different
species and to making the
"species" the ultimate unit of
taxonomy.

14
Among Ray’s publications
were Catalogus
plantarum (1660),
Ornithology (1676) (see
plate right) and Historia
insectorum (1710).

In 1674, Antoine van Leeuwenhoek,
sent a copy of his first observations
of microscopic single-celled
“animalcules” to the Royal Society
of London.

16
His first microscope
consisted of one
very small spherical
lens inserted in a
tiny hole in a metal
plate.
Antoine van Leeuwenhoek,
is known as the "father of
microscopy“.

Until then the existence of
such microscopic organisms
was entirely unknown.
17
At first these organisms were divided into animals and
plants and placed in the appropriate Kingdom.

Carl Linne (1707-1778) , a
Swedish doctor and naturalist,
studied plants and other
organisms and published
several important books.
He was undoubtedly the most
important scientist where
classification is concerned and
is considered the father of
taxonomy.

In 1753 Linnaeus
published his Systema
Naturae describing plants
and seeking to find out
how they were related to
each other.

In the same year (1753) he published Species lantarum
which reolutionised the way in which scientific names
were applied to plants and fungi.

In this publication, Linneus stated that plants should be
identified according to their flowers, not their leaves
or other organs. This was a very intuitive observation
and the method is still used today.

Before Linneaus the
Wild Briar Rose was
known to botanists as
Rosa sylvestris alba
cum rubore, folio
glabro (pinkish white
woodland rose with
hairless leaves), or
Rosa sylvestris
inodora seu canina
(odourless woodland
dog rose).

How was one to know if
these names referred to
the same plant or two
different ones?

By the Linnaean System the plant became simply Rosa
canina
25

27
Modern Classification systems use a two-word naming
system called Binomial Nomenclature developed by
Linnaeus to identify species.
Vicia sativa L.

Institute of Earth Systems 28
In this system, the FIRST WORD identifies the genus name
of the organism. A genus (plural form = genera) consists of
a group of similar species.
The SECOND WORD, the descriptive word, often describing
a characteristic of the organism, follows the genus name.
Vicia = common name in Latin
for vetch
sativa = cultivated

29
Thus, the scientific name of each species is made up of the
generic name, followed by the descriptive specific name.
Vicia sativa Vicia faba

The genus name always begins with a capital letter, but
the specific (second) name always begins with a lower
case letter. Both names are always italicized or
underlined.
30
Sometimes the genus
may be written as an
initial when it does not
create confusion but the
specific name is always
written in full.
Vicia sativa
or
V. sativa

The binomial name may
be followed by another
word which indicates the
sub-species.
Vicia sativa nigra
or
Vicia sativa ssp nigra

While he was naming organisms, Linneus
also placed them in groups according to
their characteristics
Istitut tal-Agrikoltura 32

34
Lineus placed organisms in
groups known as taxa (singular
taxon) according to their
characteristics
The broader the taxon the more
general its characteristics & the
more species it contains.
Each taxon is a further broken-
down level of classification found
within each kingdom.

The Kingdoms are divided into the following groups:
Phylum (aka Division or Type)
Class
Order
Family
Genus
Species
Each group has also super-groups and sub-groups.
35Institute of Agriculture

Classification of a
tick.

Olive fly has the scientific name Dacus oleae.

D. papayae
40
D. punctatifrons D. newmanni
D. tryoni D. cucumis D. oleae

Genus Dacus
Istitut tal-Agrikoltura 41
Genus Ceratitis

Family
Tephritidae
42
Family
Muscidae)
Family
Culicidae
Family
Phlebotomidae
(sandfly)

Order Diptera
43
Order Lepidoptera
Order
Hymenoptera
Order
Coleoptera

Classi Insecta
44
Class Arachnida
Class Crustacea

Phylum Arthropoda
45
Phylum
Nematoda
Phylum
Chordata
Phylum
Mollusca

As can be seen, therefore, classifying an organism does
not consist only in naming it but, more importantly,
placing it within a context of similar organisms.

Is the striped zebra related to the
striped tiger or the grey rhino?

The zebra is related to the rhino (same order) because,
they have the same structure of the hooved odd-toed feet.
Such a character is
what a taxonomist
looks for when
classifying an
organism.
The bone structure
of the foot is
therefore a more
significant
character than the
pattern of the coat.

The extinct Tasmanian wolf (thylacine) had the same
dentition as the wolf. Are they related?

The two mammals are not related because the thylacine
was a marsupial while the wolf is a placental animal.
A newborn marsupial in its
mother’s pouch.
A newborn wolf is
relatively self-sufficient
The reproductive system is considered more important
than dentition, to show relationship.

The characters which are relevant to classification are
known as
diagnostic characters or taxonomic characters
One of the most important skills of the taxonomist is
recognising which particular characters are of taxonomic
significance.
Example: Wings are
taxonomic characters for
insect orders.

This is the
“history” of a group
of organisms
especially as
regards their
ancestry. In
Greek, Phylon
means ‘group’ or
‘tribe’ while
Genesis means
‘creation’ or ‘birth’.

When a group is descended from one ancestor it is said
to be monophylitic.
When the group
is descended
from two or
more ancestors
it is said to be
polyphylitic.

Sometimes, a common ancestor may give rise to more
than one group.
In this case each
group, representing
only a part of the
descendents of that
common ancestor, is
said to be
paraphylitic.

Although the system devised
by Linneus is still in use, time
has obviously brought
changes.
One of them is that while
Linneus divided all living
creatures into two kingdoms*
(Plant and Animal), these have
now been divided into five.
55
*He was influenced by Aristotle
according to whom the universe was
made up of three Kingdoms:
mineral, plant and animal.

By the mid-19th century it
had become clear that the
existing boundary between
plant and animal kigdoms
as as created by Aristotle
was becoming blurred and
unsatisfactory.

In 1866, a German biologist, Ernst Haeckel proposed a
third kingdom of life to include the unicellular organisms.
Institute of Agriculture 58
Protista

By mid 20th century the
importance of having an
enclosed nucleus became
more evident and another
kingdom (Monera) was
proposed for organisms
not having such a nucleus.

The organisms without a
nucleus enclosed by a
membrane were called the
Monera and comprised the
bacteria.

The next innovation involved the
breaking up of the Plant Kingdom
to take into account the
differences between true plants
and fungi.

This system, proposed in 1969, has now become a
popular standard and, with some refinement, is still
used in many works. It forms the basis for modern multi-
kingdom systems.

From around the mid-1970s onwards, there was an
increasing emphasis on DNA to assess relationships
between organisms. This is now considered more
significant than outward appearance and physiology.

Yet another new kingdom is sometimes being proposed
today. The Protista (single-celled with enclosed
nucleus) would be broken up to divide the algae from
the rest of the unicellular organisms. This idea is not yet
widely accepted.

Monera form the only
kingdom composed of
prokaryotic
organisms.
They have a cell wall
but lack membrane-
bound organelles,
including a nucleus.

Monera can be rod-shaped,
spiral-shaped or round and may
have hairs (cilia) or tails
(flagella) that let them move
around. They reproduce by
dividing and their populations
can grow very quickly.

The kingdom is divided into two main groups:
Myxomonera – blue-green algae
Mastigomonera - bacteria

These photosynthesising organisms live in water and
form groups of cells. They can survive in polluted
waters and the remains of ancient organisms become
petroleum.

Bacteria are present in most
habitats on Earth and are
extremely abundant: their
bimass exceeds that of all
other organisms combined.
They help to recycle nutrients,
through processes such as
the fixation of nitrogen
from the atmosphere
and putrefaction.

The Archaebacteria, the most ancient members of this
kingdom, are so different that they may belong to a
separate kingdom.

These are
organisms that
don’t seem to fit
anywhere else.
They include some
of the earliest living
things on Earth and
gave rise to fungi,
plants, and
animals.
The first eukaryotic
cells are thought to
have been protists.
Slimemould

The most ancient eukaryotic
kingdom, protists include a wide
variety of organisms that can be
heterotrophic or autotrophic.
Perhaps they are
best defined by
what they are not:
they are not fungi,
animals, or plants.

The oldest fossils of eukaryotic cells are 1.5 billion
years old although the earliest eukaryotic cells may
have arisen 2.1 billion years ago. The oldest fossils of
prokaryotes are 3.6 billion years old.
.

Th kingdom shows great diversity. It is made up by many
groups of which the main ones are:
Animal-like - all motile (protozoa)
Plant-like - mostly non-motile; photosynthetic; often called
algae or seaweeds
Fungus-like - grow in dark, shady habitats and are called
slime moulds; most are colourful and can be found
underneath rotting logs or leaves.

A fungus is a eukaryotic organism that digests its food
externally and absorbs the nutrient molecules into its cells.
Most are multicellular but some (the yeasts) are simple
unicellular organisms probably evolved from multicellular
ancestors.

The fungus body is made of tiny
filaments or tubes called hyphae,
usually with cross-walls (septa) with
a chitin cell wall.
Each hyphae is one continuous cell
that continually grows and
branches.

Tangled mats of hyphae are
known as mycelium.
Hyphae grow rapidly from the
tips by cell division

Most fungi reproduce asexually and sexually by means
of spores.
Asexual reproduction produces identical organisms and
is the most common method used. Sexual reproduction
occurs when nutrients or water are scarce. Wind,
animals and water spread spores.

Sexual sporulation is the
main character used to
identify and classify fungi.

The majority of fungi are decomposers, breaking dead
organisms down and returning inorganic nutrients to the
ecosystem.
Many other forms are
parasitic, especially on
plants but sometimes also
on animals or other fungi.

Still other forms are predatory on animals such as
nematodes.
90

Some fungi also cause
disease (yeast infections,
rusts and blights), while
others are useful in
baking, brewing, as
foods, drugs and sources
for antibiotics.
Claviceps purpurea, causing
ergot disease of rye

The cell walls are similar in
structure to plants’ but differ in
chemical composition - fungal
cell walls are composed mostly
of chitin rather than cellulose.
This is one of the taxonomic characters that distinguish fungi
from true plants

Most fungi store glucose as glycogen (like animals)
while plants store food as starch.

Fungi may be grouped in four Classes:
Oomycetes – Mycelium without septa. Reproduce by
conjugation of large and small cell (oogonium and
antheridium).
Ascomycetese - Sexual reproduction via spores
produced in asci (sac-like cases)
Basidiomycetes - Sexual reproduction via club-shaped
reproductive structures: basidia.
Deuteromycetes - Diverse
group of unclassified species.
Sexual structures unknown,
hence also called Imperfect
fungi.

Plants are immobile, multicellular eukaryotes that
produce their food by photosynthesis and have cells
encased in cellulose cell walls.

They are important sources of oxygen, food,
textiles, construction materials and other products.

They are important sources of oxygen, food, and
clothing/construction materials, as well as pigments,
spices, dyes, and drugs.

The kingdom
Plantae includes all
land plants:
mosses, ferns,
conifers and
flowering plants.
With more than
300,000 species, they
are second in size only
to the Phylum
Arthropoda.

Among the characters which distinguish plants from
other organisms are the following:
Multicellular
Cellulose cell walls
Autotrophic
Growth occurs in specific regions
Reproduction vegetative or sexual

Plants have adapted to life on land and have
adaptations to reduce water loss, such as:
• Leaves and stems are covered by an impermeable
waxy cuticle.
• Leaf openings
(stomata) that open and
close to regulate gas
and water exchange.

Plants are divided into two main groups:
Green Algae -
Bryophytes - Non-vascular plants
Tracheophytes - Vascular plants

All plants are
thought to have
evolved from
ancestral green
algae.
Within the plant
kingdom, there
are many
different types

The Plantae may be divided first of all in two main groups:
Green algae
Embryophytes (terrestrial plants)

These are a large group from which the embryophytes
(higher plants) emerged. There are about 6000 species.
Many are single cells, while other species form colonies or
long filaments.

The advantages of being a
water plant include:
More access to water
More support (from the
surrounding water)
Water helps disperse gametes

The advantages of being a land
plant include
• High concentrations of CO2 in air
(compared to water)
• More access to sunlight
• Initially: less competition for
resources, fewer predators

This group includes:
Hornworts – Liverworts – Mosses

These small plants lack specialized tissues for
transporting water, minerals, and organic nutrients and
have no roots, leaves or stems. Because of this they dry
out very quickly, so they are usually found in moist
habitats.

The main
character used to
divide
Tracheophytes is
whether they
produce seeds or
not.

This group is divided in 2 sections:
Seedless Plants – including horsetails and ferns
Seed Plants – Plants which produce flowers and seeds

Seedless tracheophytes are further divided into two groups:
Lycophytes – club moss and horsetails
Pterophytes - Ferns
Typical lycophytes – club mosses

Ferns grow in moist, shady habitats
because their water-saving
adaptations are not as efficient as
those of other plants. Their leaves
are called fronds.

Classification of this group varies but we’re considering
here a simplified version which contains two Classes. :
Gymnosperms – conifers
Angiosperms – broad-leaved plants

The two groups of seed-plants are divided by whether
or not they have enclosed seeds -protected inside a fruit
- or if the seeds are exposed to the environment.
Tracheophytes
Seedless Seeded
Gymnosperms Angiosperms
“naked” or
exposed seeds
Flowers produce fruit
w/ enclosed seeds

Characters of Gymnosperms
(Conifers)
– Seed is not protected by
fruit
– Has cones
Characters of Angiosperms
(Flowering Plants)
– Seed is further protected
by a fruit
– Has flowers

Gymnosperm means “naked
seed”.
They are more advanced than
ferns and do not have spores
but seeds.
Their seeds lack a protective
enclosure (unlike flowering
plants which have flowers and
fruit).
Examples of gymnosperms:
Conifers (pine trees),
cycads,
Ginkgo biloba

Conifers, which bear seeds in cones, are most important
group of gymnosperms.
Staminate cones – male cones
Ovulate cones – female cones

Cupressaceae, Pinaceae, Taxaceae, Taxodiaceae

They do not produce any flowers or fruit. The seeds are
carried on an open ‘scale’.

Conifers are adapted to temperate to cold regions. They
have narrow leaves (needles) to help conserve water
and protect them from the cold. The plants are covered
by resins for protection from predators, fire, etc

Angiosperm means “covered seed”. They have
flowers, fruits with seeds.
Live everywhere – dominant plants in the world
260,000 species (88% of Plant Kingdom)

The phylogenetic classification of Angiosperms is
complex and in continuous evolution. We will here use a
simplified version that is sufficient for our purposes
Angiosperms may be divided in two sub-classes:
Monocotyledonae – one cotyledon
Dicotyledonae – two cotyledons.
The Dicotyledonae may be further subdivided into
several groups.

Although the names of the two sub-groups are derived
from the number of cotyledons, there are several other
taxonomic characters which distinguish them.

Animals are organisms with the following
characteristics:
Multicellular Have cell membranes
Heterotrophic Growth occurs all over body
Motile Sexual Reproduction
Irritability Food stored as glycogen

Animals are multicellular, heterotrophic eukaryotes that
are capable of motility at some stage during their lives,
and that have cells lacking cell walls. Animals provide
food, clothing, fats, scents, companionship and work.

The Protozoa are now placed in the Kingdom Protista
and no loner considered animals so that the grouping
matazoa has become irrelevant.

Traditionally (going back to Aristotle) multicellular animals
were split into two major groups:

The grouping vertebrates has now been replaced by
Chordates as there are animals which have a spinal chord
but no vertebrae.

This is an informal and not a monophyletic grouping as
it comprises practically all animals except Chordates.

Invertebrates are animals that do not have backbones.
They constitute 97 % of the Animal Kingdom and can
be found in aquatic and damp encironments. Several
types have have exoskeletons.

Characters include:
Bodies made of loosely
joined cells

Characters include:
Thin sack-like bodies
Tentacles with stinging cells

The Cnidaria include the jellyfish and sea anemones.

Characters include:
Bodies divided into five parts
Spiny outer covering

Characters include:
Small size
Flat worm-like bodies

Have long thin round non-
segmented bodies covered by
a cuticle.
Mouthparts consist of a set of
stylets and a pharynx.
Nematodes may be parasitic
on plants or animals or free-
living, predatory or living on
decaying matter.

Characters include:
Round worm-like bodies
divided into segments. They
live mostly on decaying
matter but some are parasitic
(leeches)

Have lots of legs and segmented bodies. There are several
Classes of arthropods including:
– Arachnids
– Centipedes
– Millipedes
– Crustaceans
– Insects

Characters include:
• Four pairs of legs.
• Bodies may be
divided into two
sections

Long thin segmented bodies. One
(Chilopoda) or two (Diplopoda) pairs
of legs on each body segment.

Characters include: Five-seven pairs of
legs First pair often used as pincers

Characters include:
Three pairs of legs.
Bodies divided into three
sections.
Two pairs of wings

Characters include:
Fleshy pad for locomotion.
Shell external or internal

These are animals with a backbone.
There are five groups of vertebrates:
–Mammals
–Birds
–Reptiles
–Amphibians
–Fish

Paedocypris progenetica, the world's tiniest fish, which
lives in swamps in South-East Asia.

Have wet scales
Lay eggs in water
Live in water

This is the largest group of vertebrates. They live only in
water, breathe through gills and are usually covered in
scales.

The old class pisces is no longer used. Instead fish are
divided into three classes:
a) Agnatha - jawless fish
b) Chondrichthyes - cartilaginous fish
c) Osteichthyes - bony fish
a
b
c

Loss of habitat makes
this the most endangered
group of all animals.

Amphibians are cold-blooded and hatch from
jelly-coated eggs. As juveniles they have gills
and live in water. Their skin is smooth
and moist.

The 6000+ species are divided in three orders:
Anura - frogs
Caudata or Urodela - newts, salamanders
Gymnophiona or Apoda - caecilian

One of the world tiniest
reptiles

Reptiles are covered in scales and
lay leathery-shelled eggs on land.
Their body temperature varies with their
environment and they are always free-living.

The old Class Reptilia has around 8000 species in four
orders:
Crocodilia — crocodiles
Sphenodontia — tuataras
Squamata — lizards and snakes
Testudines — turtles and tortoises

Birds are warm-blooded, have true wings and
feathers and lay hard-shelled eggs. The usually
have hollow bones.
They are always free-living, never parasitic.

There are about 10
thousand species divided
into 20 orders. The main
taxonomic differences
regard the bills and feet.

Characters include:
Milk production
Presence of hair
Presence of diaphragm

Produce milk to feed their young. Females
possess a modified sweat gland – a mammary
gland – activated by hormonal changes that occur
with pregnancy. In fact, this trait is what inspired
the term “mammal,” a derivation of “mammary.”

Skin covered with fur or hair. A characteristic that's seen
only in mammals.

Mammals are divided into
14 orders
Monotremata and
Marsupials are two of them

Mammals are divided into 14 orders.

Emp1003 biodiversity and classification

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