This document discusses biodiversity and classification. It begins by defining biodiversity as the total number of species in an area and discusses the levels of biodiversity - genetic, species, and ecosystem diversity. It then focuses on biodiversity in Southern Africa, noting that South Africa has a high level of endemism and biodiversity. The document explains the importance of scientific naming for organisms and discusses several systems for classifying life, including the two kingdom, five kingdom, and three domain systems. It emphasizes that classification helps scientists study and organize the wide variety of lifeforms.
2. 1
Table of content
Topic Page
Biodiversity, change and continuity 2
Biodiversity and Endemism in Southern
Africa
3
Three levels of biodiversity 3
Naming Things in Science 5
Classification as a way of organising
Biodiversity
6
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BIODIVERSITY, CHANGE AND CONTINUITY (biodiversity of life on Earth)
Introduction
Living organisms occur in different life forms and sizes. Examples different species of
other life forms on earth includes microscopic organisms found in soil and water, such
as fungi and lichens which grow on barks of trees, water plants, starfishes, dolphins,
lizards, snakes and the “big five” animals that we already learned about. Note that
these animals occupy a wide range of ecosystem and they are genetically different
from each other. This wide range of species and number of organisms making up each
species within communities is called ‘biodiversity’.
Biodiversity refers to the total number of species found in an area. Includes
the large variety of species, different ecosystems and genetic differences.
Endangered species: species in danger of extinction
Threatened species: species likely to become endangered in the near future
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Figure 1. Diversity of organisms
Biodiversity and Endemism in Southern Africa
The term ‘endemic’ was used and explained in environmental studies. So no, let us
elaborate a little more for a better understanding of the term.
Organisms that occur naturally or originally within a country or a region are said to be
indigenous to that particular country or region. We have living organisms that are or
have been introduced or brought into a country or a region, this are called exotic or
alien species. Exotic or alien species are not indigenous to a country or region; they
have been ‘introduced’.
It is possible for a species to occur natural in more than one country or region. We
therefor say this organism is indigenous to a number of countries or regions. Some
species occur natural to only one country or region, we say this plants are indigenous
to that particular environment. But since it occurs in only that particular place and
nowhere else in the world, we say these species are endemic to that country or region.
The term ‘endemic’ means that these organisms cannot be found anywhere else in
the world beside that specific country or region.
‘Endemism’ is an adjective derived from the word ‘endemic’. It describes the number
and range of species that are endemic to a country or region.
Three levels of biodiversity
Ecologists describe biodiversity as an attribute of three other levels of biological
organization:
Genetic diversity: variation among members of a population, higher genetic
diversity – higher chance of survival.
Community or species diversity: community composition, increases the
levels of biodiversity
Landscape or ecosystem diversity: a group of interacting ecosystems within
one landscape.
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2(a) 2(b)
2(c)
Figure 2(a) ecosystem diversity, 2(b) genetic diversity and 2(c) species diversity
Activities on what we covered at the following links:
https://play.kahoot.it/#/scoreboard?quizId=06c5b2b8-eef8-4892-ad66-f576feda60aa
https://b.socrative.com/student/#quiz
From our earlier study of biomes, we already know that:
There are seven different biomes in South Africa (eight, if we include Lesotho,
Swaziland, Mozambique, Botswana and Namibia).
Vegetation within these biomes goes from desert plants, to grassland, to
shrubs, woodland and forests
These biomes support a wide variety of another life forms including animals
Many species of living organisms found in these biomes are endemic i.e. they
are not found anywhere else.
South Africa has a land surface of area which represent just 1% of the earths total land
surface. However, it is extremely rich in terms of the variety of life forms it contains.
There are species of plants, mammalian species, bird species, reptile species and
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amphibian species, species of fresh- water fish, species of marine fish and insect
species.
As a result of the large variety of life forms we have in South Africa, our country is
placed third in the world in terms of biodiversity.
Our country is also important in terms of the number of life forms that occur nowhere
else in the world i.e. in terms of the number of endemic species. Approximately 12%
of the plant and animal’s species found along our coastal areas are endemic. In terms
of the number of endemic species of mammals, birds, reptiles and amphibians, South
Africa ranks as the 5th richest country in Africa and the 24th richest in the world.
Unfortunately, many of the species are threatened with extinction.
Three places in South Africa are recognised as international biodiversity ‘hot-spot’
because of the variety of life forms they support and the number of endemic species
found in each. These are the Cape Floristic Region (fynbos), Succulent Karoo, and
Maputoland-Pondoland-Albany hotspot of the Eastern Cape. Almost 80% of the plant
species found in the Cape Floristic Region are endemic, including an entire group of
flowering plants. In the Succulent Karoo biome 40% of the species are endemic. And
1 endemic species of amphibian.
Naming Things in Science
The common or popular of plants or animals are useful in everyday conversations.
However, scientists prefer to use scientific names of living organisms rather than their
common names for the following reasons:
The same organisations may be known by different names in different countries
or in different parts of the same country. For example, what is known as a
‘sardine’ in KwaZulu-Natal and the Eastern Cape is known as ‘pilchard’ in other
parts of the country. Similarity, the ‘panther’ is also known as a ‘cougar’, ‘puma’
or ‘mountain lion’, in different parts of the United States of America.
The same common name might be used for different species. For example, the
name ‘daisy’ might be used for an entire group of plants which have ‘daisy-like’
or ‘ester’ flowers. Twenty-one different species fish have the common name
‘sardine’
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If we use the common names, especially when we are communicating with someone
from outside our own local arears. Then it is possible that the other person might make
a mistake regarding the actual organism.
To avoid this problem, a system of scientific names has been developed which all
scientists now use. The system was first developed by the Swedish scientist Carolus
Linnaeus (1707-1778), more than 200 years ago. In this system every living organism
is given a name with two parts. The system is called the binomial system (‘bi’ means
two), the first part of the name is called its generic or genus name and the second part
is its specific or species name.
Activity.
Assignment
Biodiversity and classification
Scientist use scientific names to identify species.
1. Do a research where by you explain why scientist use scientific names
instead of using common names which we all use to identify species (30
marks)
For the rubric check the following link:
https://docs.google.com/document/d/1tiyIHhGHJuUbKcKIVrKhd4_wxDCJVz5tIhkj
eoziUrU/edit
Classification as a way of organising Biodiversity
Sorting and grouping things according to similarities and differences is called
classification. Classification helps scientist to organise the many different species of
life forms into groups. Such classification makes it more convenient for scientist to
study this life forms. For example, a scientist might study the internal anatomy of
different species of fish to see if they are built according to a similar pattern or not. If
similar studies are made on frogs, reptiles, birds and mammals, comparisons may be
made among this groups. The science of naming and classifying the wild range of
living things is called taxonomy.
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Classification: the scientific practice of identifying, naming and grouping of living
organisms.
Branches of biology that deal with classification:
Taxonomy deals with describing and naming organisms.
Systematics deals with grouping and arranging the described taxa into a
hierarchical classification.
The History of Classification of Life Forms
We put things that have the same characteristics into one group. Then we separate
this group of things from another because of their differences. Scientist work in the
same way when dealing with living organism. That is, the place organisms which share
the same characteristics into one group and separate this from another group because
of the difference in characteristics.
All modern systems of classification of living organisms came from the work Aristotle
and Carolus Linnaeus. Aristotle classified all living organisms into two groups: plants
and animals. He classified plants into three groups: as herb, shrubs or trees. He
classified animals into two ways. In one method he separated those that had red blood
and those that did not. In another method he classified them according to how they
moved (walking, flying or swimming). He classified about 1000 plants and animals
together.
Example of Classification Systems
The two-kingdom system, the five-kingdom system and the three-domain system are
three of the more popular ways in which living organisms may be classified
Two-kingdom system
In the two kingdom system of classification, all living organisms are placed into the
large groups or kingdoms. These are the Kingdom Plantae (Plant Kingdom) and
Kingdom Animalia (Animal Kingdom).
The two-kingdom system of classification uses the following characteristics to
distinguish between plants and animals.
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Plants are able to manufacture their own food because they have chlorophyll
while animals cannot manufacture their own food because they do not have
chlorophyll.
Plants have a cellulose cell wall, while animals do not have a cellulose cell wall.
Plants remain fixed at one point, while animals are able to move from one place
to another.
Five-kingdom system
Robert H. Whittaker developed a system which classified all living organism into the
following five kingdoms:
Kingdom Monera
Consists of all bacteria – simple, single celled organisms with no
nucleus
Kingdom Protista
Consists of single celled or simple multi-cellular organisms
Some obtain energy by photosynthesis – algae.
Some ingest other organisms
Some absorb molecules through the cell membrane
E.g. Amoeba, Euglena
Kingdom Fungi
Single celled –e.g. yeast- to multi cellular organisms
Body composed of very fine threads – saprophytic nutrition
Kingdom Plantae
Plants
Multi cellular terrestrial organisms
Cells have cell walls, obtain energy through photosynthesis
Kingdom Animalia
Animals
Multi cellular, aquatic and terrestrial organisms
Cells have no cell wall, feed on other organisms
Whittaker used to distinguish the five kingdoms, we need to understand the term
prokaryote, eukaryote, autotrophs and heterotrophs, decomposers, unicellular
and multicellular.
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The Three-Domain system
Domain Bacteria
Prokaryotic unicellular organisms.
Bacteria
Bacteria are important heterotrophs – break down dead organic matter
into inorganic matter used by plants to grow.
Cyanobacteria – only bacteria that can photosynthesise (contain
chloroplasts).
Domain Archaea
Prokaryotic unicellular organisms.
Archaea differ from bacteria in their rRNA base sequences & their unique
plasma membrane and cell wall chemistry.
Can survive in extreme environmental conditions.
Domain Eukarya
Unicellular/multicellular eukaryotes (has membrane bound nucleus).
Possess organelles.
Sexual & asexual reproduction.
Activity:
Create a chart which will explain the classification systems you have learned about.
(35 marks)
For the rubric click the link:
https://docs.google.com/document/d/147VZu57IKUhrkXORyhAdRZZZclLjAKvNFnqg
RjHtQrc/edit