UNIT 4: INTRODUCTION TO BIODIVERSITY
Species is a group of closely related organisms which are capable of
interbreeding to produce fertile offspring. Occasionally two organisms which
are genetically closely related but not of the same species can interbreed
to produce infertile offspring. For example, a cross between a donkey and
a horse, produces a mule, which is infertile. Hence, a donkey and a horse
do not belong in the same species. Another example includes lions and
tigers belonging in different species. However, when a male tiger mates
with a female lion they can have fertile offspring called tiglon, although the
offspring of female tigers and male lions called ligers are not fertile. Note
that normally tigers are forest dwellers and lions are plains dwellers and they
are ecologically isolated. Breeding has only been observed in captivity.
An ecological population is a group of individuals of the same species
which live in a particular area at any given time.
An ecological community consists of populations of different species
which live in the same place at the same time, and interact with each other.
A habitat is a specific area or place in which an individual organism lives.
When a habitat is very small it is regarded as a microhabitat.
Within the habitat, an ecological niche is the status or the role of an
organism in its habitat or the mode of life of an organism within its habitats.
For example, insects are pollinating agents and preys of insectivores.
In an environment, communities are influenced either by abiotic components,
also called abiotic factors. These are the non-living physical aspects of the
environment such as the sunlight, soil, temperature, wind, water, and air.
Communities are also influenced by biotic components, or biotic factors.
These are the living organisms in the environment.
The biosphere is the whole of the earth’s surface, the sea and the air that is
inhabited by living organisms. The biosphere is made up of all ecosystems.
An ecosystem is a collection of all the organisms that live together in aparticular place, together with their nonliving, or physical environment.
Biodiversity is defined as the full range of variety and variability within and
among living organisms and the ecological complexes in which they occur.
In other words, biodiversity is the variety of life. It refers to the totality of the
species including the genetic variation represented in the species populations,
across the full range of terrestrial organisms, including vertebrates andinvertebrates, protista, bacteria and plants.
Biodiversity is can be categorized into three groups:
–– Genetic diversity (c): The combination of different genes found within
a population of a single species, and the patterns of variation found
within different populations of the same species. These variations are
caused by the gene mutations or chromosomal mutations which create
differences in individuals of the same species.
–– Species diversity (b): This is concerned with variation in number of
species and their relative abundance in an area in which they inhabit.
All species are different from each other. These could be structural
differences, such as the difference between a mango tree and a cow.
They could also be functional differences, such as the differences
between bacteria that cause decay and those that help us to digest
food. The variation in the relative abundance of species within a habitat
may be caused by different factors, mainly environmental factors which
can affect their rate of reproduction.
–– Ecosystem diversity (a) : This is concerned with variations in
ecosystems or habitats that occur within a region. Environmental
factors like climate change may cause diversity of habitats or systems
within a region.
–– Functional diversity
Biodiversity / biological diversity means the variability among living
organism from all sources and ecological complex of which they
are part. In general a species rich ecosystem is presumed to have
high functional diversity, because there are many species with manydifferent behaviour.
Looking anywhere around we can help us appreciate the beauty biodiversity
gives our environment. Beyond beauty, why is biodiversity important?
Biodiversity and its maintenance are very important for sustaining life on
earth. The points below guide carrying out of importance of biodiversity:
1. Importance to the nature
Biodiversity maintains food chain in the nature, all living things in environment
are interdependent. Animals could not exist without green plants. These
plants could not exist without animals to pollinate them. These plant are
dependent on decomposers. Whereas some living things can be niches for
others living things. Thus, living things have many complex relationships
among organisms.
They are adapted to live together in communities. If a species is lost from an
ecosystem the lost may have consequences for others living things in the
area. An organism suffers when a plant or animal it feed upon is removedpermanently from a food web.
Looking anywhere around we can help us appreciate the beauty biodiversity
gives our environment. Beyond beauty, why is biodiversity important?
Biodiversity and its maintenance are very important for sustaining life on
earth. The points below guide carrying out of importance of biodiversity:
1. Importance to the nature
Biodiversity maintains food chain in the nature, all living things in environment
are interdependent. Animals could not exist without green plants. These
plants could not exist without animals to pollinate them. These plant are
dependent on decomposers. Whereas some living things can be niches for
others living things. Thus, living things have many complex relationships
among organisms.
They are adapted to live together in communities. If a species is lost from an
ecosystem the lost may have consequences for others living things in the
area. An organism suffers when a plant or animal it feed upon is removed
permanently from a food web.
Genetic biodiversity, arboreal plants, such as trees, tend to have more
genetic diversity, on the whole, than vascular plants, such as grasses. This
holds true both within populations and within the different species.
Large populations are more likely to maintain genetic material and thus
generally have higher genetic diversity. Hence, genetic diversity plays an
important role in the survival and adaptability of a species.
Maintaining balance of the ecosystem, a population may soon exceed the
area’s carrying capacity if its predator is removed; if the symbiotic relationship
among organisms are broken due to the loss of species, the remaining
species will also be affected.
Biodiversity protects water resources, natural vegetation cover in water
catchments help to maintain hydrological cycles, regulating and stabilising
water runoff, and acting as a buffer against extreme events such as flood
and drought.
Biodiversity increases ecosystem productivity where each species, no matter
how small, all have an important role to play, a large number of plant species
means a greater variety of crops. Greater species diversity ensures natural
sustainability for all life forms.
Promote soils formation and protection, the well-being of all plants and land-
based animals depends on the complex processes that take place in soil.
Soil develop from parent material by various weathering processes. Organic
matter accumulation, decomposition, and humification are as critically
important to soil formation as weathering.
Provision of biological resources, biodiversity provides main ecosystem
service such as nutrient cycling, carbon sequestration, pest regulation and
pollination, sustain agriculture productivity. Promoting the healthy functioning
of ecosystems ensures the resilience of agriculture as it intensifies to meet
growing demands for food production.
2. Importance to people
By diverse species of plants and algae living in variety of ecosystem through
photosynthesis process, regularly supply oxygen for breathing process to
human being. Yet only a few species of plants and animals supply the major
portion of food eaten by the human population.
Drugs companies manufacture synthetic drugs are first isolated from living
things. Example, mold penicillium provides an antibiotic penicillium, cinchona
tree release antimalarial drug etc Preserving biodiversity ensures there willbe a supply of living things, some of which may provide future drugs.
Biodiversity and food security, the provisioning of clean water and diverse
food supply makes it vital for all living things, biodiversity helps regulate the
nutrients cycle and water and mitigates impacts of climate change
3. Biodiversity stability
Biodiversity can bring stability to ecosystems. These are stable if their
biodiversity is maintained. Instead of being clumped together, the plants are
scattered in many parts of the rain forest, making it more difficult for thedisease organism to spread.
4.4.1. Threats of biodiversity
the main causes of biodiversity loss can be attributed to the influence of
human activities on ecosystems. Threats to biodiversity may include:
a. Habitat loss and the degradation of the environment
The habitat loss and the degradation of the environment occur in different
ways.
The most occurring, are tree cutting, agriculture and fires. These human
activities lead to the alteration and loss of suitable habitats for biodiversity.
As a consequence, there is a loss of plant species as well as the decrease
in the animal species associated to this plant diversity.
b. ntroduction of invasive species and genetically modified
organisms
Species originating from a particular area are harmful to native species
also called endemic species when they are introduced into new natural
environments. They can lead to different forms of imbalance in the ecological
equilibrium, so that endemic species may fail to compete with introduced
species, and they may affect the abundance and distribution in natural
habitat.
c. Pollution
Human activities such as excessive use of fertilizers, and increased pollutants
from industries and domestic sewage affect biodiversity. They contribute to
the alteration of the flow of energy, chemicals and physical constituents of the
environment and hence species may die as a result of toxic accumulation.
d. Overexploitation of natural resources
Increased hunting, fishing, and farming in particular areas lead to the decrease
and loss of biodiversity due to excessive and continuous harvesting without
leaving enough time for the organisms to reproduce and stabilize in their
natural habitat.
e. Climate change
This is a change in the pattern of weather, related changes in oceans, land
surfaces and ice sheets due to global warming resulting from man’s activities.
Increasing global temperatures have resulted into melting of icebergs raising
sea levels and so flooding coastal areas eventually affecting the niche, andthese may take the lives on many living things.
4.4.2. Consequences of loss of biodiversity
They are various consequences of loss of biodiversity that include:
–– Desertification, is thought by scientists to be a consequence of climate
change, has been considered to be related to deforestation. Disrupting
water cycles and soil structure results into less rainfall in an area.
–– Floods as a result of rising sea levels.
–– Habitat destruction for extensive farming, timber harvesting and infrastructure and settlement.
–– Decrease in food production as result of change in pattern of weather that affects productivity
–– Large scale deforestation has a negative effect on nutrient recycling and can accelerates soil erosion.–– Diseases that come as effects of floods and malnutrition due to famine
1.Explain what is meant by a habitat and make a list of all the habitats you can see in your school compound.
2. Pollution is one of the causes of aquatic biodiversity loss.
a) What do you understand by water pollution?
b) Outline human activities that contribute to water pollution
c) Discuss how polluted water affects aquatic living organisms?d) Relate desertification with biodiversity loss.