1.
An introduction to ecology
Ecology is defined as interactions between abiotic
(non-living) and biotic (living) components that occur in the environment,
these communities of organisms and how they react with each other and other
abiotic and biotic factors create an ecosystem, there are two types of
ecosystem aquatic and terrestrial. An ecosystem is the community (all living
species) as well as their environment that surrounds it, an ecosystem is the
main ecological unit containing both abiotic and biotic components through
which nutrients are cycled and energy flows. However to permit these cycles the
ecosystem must contain a number of interrelationships among its components
(water, soil, nutrients, producers, consumers and decomposers) The function
of the ecosystem is related to the flow of energy and the cycling of materials
through the components of the ecosystem. The total amount of energy that flows
through a system depends upon the amount fixed by plants or producers, as energy
is transferred from one feeding level to the next, a portion of energy is lost
from further transfer. This limits the mass and number of organisms that can be
maintained at each feeding level, ecosystems are often broken up according to
their positions in a food chain .i.e. their trophic level. This is
explained in the diagram below…Ecosystems tend toward to move towards,maturity.
In doing so, they pass from a less complex to a more complex state in a process
called succession (Chapman and Reiss, 1999).
Figure 1. Diagram to show trophic levels.
Mechanisms of evolution
The easy way to understand evolution is that evolution is a
change in the gene pool of organisms over any given time. Evolution plays an
important role in ecosystems and how they run. Some of the mechanisms of
evolution are gene flow, genetic drift, natural selection, mutations and
descent with modifications. Evolution only occurs when there is a change in
gene frequency within a population over a period of time. (Chapman and
Reiss, 1999).
Descent
with modification refers to passing on traits from parents to
their offspring, i.e. hereditary, this is classed as the gene which holds information
about any organism for example their behaviour, development and also their
appearance. The genes are passed onto each generation, however not exactly the
same gene is always passed on, the organisms that are better suited for a
particular environment are more likely to pass on their genes, overtime the
gene similarities in the population change this is when evolution takes place (Berkley,
2014).
Mutation is a
change in DNA. DNA effects how something behaves and how it looks, some
mutations cannot be passed onto their offspring so does not affect evolution,
however the mutations that do effect evolution are galled germ line mutations
these are passed onto offspring. Germ line mutations is the presence of an
altered gene within the egg and sperm (Genetics home reference, 2014).
Mutations can happen for different
reasons, it can happen due to exposure to certain chemicals .i.e. cigarette
smoke or DNA fails to copy accurately. Evolution then takes place due to
different DNA passed onto their offspring resulting in different organisms
being born (Genetics home reference, 2014).
Gene Flow is basically any
movement of genes from one population to another, it can also be called
migration. Within a population it can introduce or reintroduce genes to a
population, this increases the genetic variation in that population, also
moving genes around across a population can make populations genetically
similar. It is more likely that two populations will evolve into two species if
there is less gene flow (Palomer, 2012).
Genetic Drift is a change
in a type of genes in any population due to some completely random occurrence,
genetic drift in small populations can result in big changes to organisms but not
so much in large populations (Palomer, 2012).
Natural Selection is a theory
by Charles Darwin. Darwin’s five theories were
Common descent – organisms are descended from one or
several common ancestors and have diversified (variety)
Evolution – Species come and go through time and change
until they exist.
Species multiply- The diversification of life involves
populations of one species diverging (going in different directions) until they
become two different species.
Graduation- Evolutionary changes occur through small
changes within a population and natural selection, Evolutionary changes occur
through variation between individuals.
Natural selection- evolutionary changes through variation
of individuals
(GCSEbitesize, 2014).
In simple terms Darwin’s
theory is that all life is related and has descended from a common ancestor and
is a slow gradual process.
Darwin’s theory of evolution
states that evolution happens by natural selection, the key points are …
·
individuals
in a species show a wide range of variation
·
individuals
with characteristics most suitable for their environment are therefore more
likely to survive and reproduce
·
the genes
that allow these individuals to be successful are passed to their offspring
Individuals that are poorly
adapted to their environment are less likely to survive and reproduce, this means
that their genes are less likely to be passed on to the next generation.
Variation can be caused by both the species genes and their environment but it
is only variation caused by genes that can be passed onto the next generation
(Gcse bitesize, 2014).
However there is evidence to
support Darwin’s theory, one key piece of evidence is “Darwin’s finch” (as
illustrated in figure 2) on the Galapagos Islands, different species of the
same bird live on the island. All the birds have different size and shape
beaks, as a result of the island being isolated there is a lack of competition
therefore the birds have been able to eat different forms of food without
competing with each other. However a common ancestor was found living on the
island with whom which the birds all have the same traits their beak being the
only exception, therefore these species are evidence of evolution and have
adapted to eat different sources of food (Biology online, 2014).
Figure 2: Evolution of Darwin’s
finches. Source: www.chs.helena.k12.mt.us
Another key piece of Darwin’s
theory was the fossil record which is an ongoing debate between evolutionists.
The fossil record shows a history of development between one species and another,
at first simple organisms are found, then newer, more complex organisms appear
over time. The characteristics of the newer organisms appear to be modified
forms of characteristics of the older simpler organisms. The relationships between the simpler to more complicated and
new and old life forms is strong evidence of evolution (about religion, 2015).
However the problem with the fossil record is it contains gaps, not all
organisms fossilise well and some fossils are destroyed by the earth’s cycles,
also some fossils are yet to be discovered. There is one big piece of evidence
however which disproves evolution the “Cambrian Explosion”, even Darwin himself
stated that it was a big problem for his evolutionary theory (Paleobiology,
2014).
The Cambrian explosion refers to the sudden appearance of a variety of
complex animal’s plans with minimal skeletonised remains. It happened about 543
million years ago, scientists refer to the event as an explosion because of the
huge amount of evolutionary activity occurred in a short space of time (20
million years) which is a aa short space of time in evolutionary
terms, before the Cambrian only soft bodied life forms existed (Biologos,
2014).
The
Adaption of Organisms to their Environment
All living organisms must be able to cope with the conditions thrown at
them in their environment if they are to survive and reproduce. Conformity
between an organism and its environment is called adaption. Adaption has many
different factors that organisms must conform to in all aspects of their
environment, it is important to remember they not only have abiotic factors to
survive .i.e. Water, wind, light and temperature but also biotic factors such
as competitors, predators and mates. Adaption has occurred through variation
which allows organisms to compete for survival, it can occur by natural
selection where organisms with good genetic traits breed more than organisms
with not so good traits or by non-genetic changes where organisms become acclimatized
to their environment (Chapman and Reiss,1999).
Every organism has certain characteristic or features that allow it to
live in its particular environment successfully, these are called adaptations
and therefore the organism has adapted to its habitat (as shown in figure 3)
A polar bear is a great example of an organism that has adapted well to
its environment in the Artic, the polar bear has
·
a white appearance which acts as camouflage against
prey on the snow therefore helps them to catch prey more easily
·
very thick layers of fat and fur to keep them
insulated from the cold
·
a greasy coat which sheds water after swimming
which helps to keep in the heat also (Gcse, 214).
Figure 3 showing polar
bears as an example of adaption source:http://thetodaystuff.blogspot.co.uk/2011/01/polar-bears-wallpapers.html
There are three types of adaptation anatomical, psychological or
behavioural. Anatomical is physical features for example an animal’s shape,
psychological adaptations are more general functions for example an organisms
ability to regulate their temperature and behavioural adaptations can either be
inherited or learnt they are the things animals do to survive an example of
this is possums who play “dead “ to avoid predators (Ehow,2014).
Table 1: table showing the three types of adaption source:
Table 1 provides a case study for how an organism may be
adapted within three distinct categories.
The
Importance of population genetics in the conservation of biodiversity
Biodiversity is used to describe the variety of life on earth and all of its natural processes, it means the number of different species living any one area and it is calculated at three different levels, ecosystem diversity, species diversity and genetic diversity.
Ecosystem Biodiversity- refers to the number of ecosystems in an area, an ecosystem is all of the plants and animals and all of its physical components in one area
Genetic Biodiversity- refers to the variability in the gene pool of a community
Species Biodiversity- refers to the number of species living in any one area
Biodiversity is needed to keep the earth enriched with food, wealth and health, it also boosts ecosystem productivity, biodiversity provides raw materials of food and medicine and not only that it protects our planet ensuring a variety of organisms live on. All species have an important role to play, a good example of why biodiversity is so important is if you have a large number of crops, greater species diversity which results in natural support for all life forms therefore resulting in a healthy ecosystem (Global issues, 1998)
The conservation of biodiversity is extremely important for
many reasons, agriculture, medicine and ecosystems. In the medicine field
researchers are looking more into natural biological resources and many treatment
and cures have been found due to the hep of animal and plant species. A big
example of this is vincristine which
is taken from the rosy periwinkle of Madagascar, which is native to the Indian
Ocean island Madagascar and has proved very useful in treating childhood leukaemia
(kew,2014).
Figure 4 illustrating the
magadasgar flower. Source:http://pk-photography.blogspot.co.uk/2008/06/catharanthus-roseus-madagascar.html
Ecosystems are another focus for the conversation of biodiversity, if there is a sudden change in a community’s environment in ecosystem, the balance of the community can change which can ultimately lead to the destruction of the ecosystem which can lead to disastrous effects. The destruction of ecosystems can lead to problems with global levels an example of this being rainforests, rainforests help to regulate climate through photosynthesis by producing oxygen and absorbing carbon dioxide, so by not conserving the rainforest we are contributing to the loss of valuable species and a change in climate (Ypte, 2014). In regards to agriculture farming has always played a part in conserving and creating habitats with a large variety of species, however over the years farming has changed and only the most productive of animals and crops are being grown and reared which ultimately means different varieties of animals and crops are in danger of becoming extinct.
Genetic diversity is extremely important in the
conservation of biodiversity, in a population there needs to be a diverse range
of genetics if the population is to survive and continue to grow, failure in
achieving this results in all the individual organisms of a species being the
same which means if a sudden disease was to hit that population the whole of
the population would get the disease resulting in possible extinction of that
particular species, however if the population had a high genetic diversity the
population would have a much higher chance of survival as some of the
individuals within that population would have the genes to fight the disease
therefore a much less chance of extinction (Ypte, 2014).
There are certain factors that affect genetic diversity….
Mating patterns- when a population interbreeds some organisms choose to breed with others based on certain traits therefore the individuals are making choices in breeding on specific behavioural choices hence why this act is named non-random mating. Non-random mating can occur in two forms both with different outcomes, one form is called inbreeding where certain individuals with similar genetic make-up are more likely to mate with each other, and the second form is called outbreeding where individuals are more likely to mate with individuals with a different genetic makeup (genotype) this leads to an increase in genetic variation (Scitable, 2014)
Migration- is the movement of organisms from one place to another entailing actual physical movement, migration can also involve the movement of alleles (a gene that is found in one of two or more different forms in the same position in a chromosome and produces a particular characteristic which varies between people for example eye colour ) (Cambridge dictionary, 2014) this is a process known as introgression (introduction from one gene complex into another) (Merriam Webster dictionary, 2015). Migration does not always have to involve the physical migration of organisms it may also involve the mating of different species where their geographical locations overlap, this is a migration of alleles from a parent to their offspring although the parents are not members of the same population. This means individuals can move from one place to another in relative to their gene pools or can also enter gene pools they were not part of resulting in a change of gene frequencies in a population (Biology as poetry, 2015).
Genetic Drift- is a basic form of evolution, it is random fluctuations of in the number of gene variants within a population, and it takes place when the occurrence of variant forms of a given gene called alleles (different forms of a gene) decrease or increase by chance over time. Genetic drift tends to happen in smaller populations where infrequent alleles have a greater chance of being lost. In basic terms some individuals leave behind more genes in their descendants than others purely by chance (Understanding evolution, 2015).
Genetic
variation in a population results from a large assortment of genes and alleles,
the ability of a population being able to survive in their changing
environments depends on whether they are able to adapt to external conditions
or not (Understanding evolution, 2015).
2. Populations of species
The Congo Basin Rainforest
The Congo rainforest
is located in central Africa and is one of the few great ecosystems left on
earth, it spans over 500 million acres and is often described as the” lungs of
Africa and has the highest level of biodiversity (Animal national, 2013).
Distribution of named plant and animal
It is the world’s second largest rainforest biome with only the Amazon being bigger and has high levels of biodiversity. There are approximately 10,000 species of tropical plants, more than 600 tree species, and 400 species of mammals, 700 species of fish and 1,000 species of birds making up the Congo (Animal national, 2013).
The Congo is
situated close to equator which means there is not changing seasons like
elsewhere so is generally warm all year round, being close to the equator
results in a vast amount of sun, but also a lot of precipitation (rain) these
two factors combined together create the perfect conditions for photosynthesis
which then in turn creates lots of plants resulting in the rainforest having
the perfect environment for thousands of different species. There are two
important factors in the rainforest the forest floor and the canopy. The forest
floor is covered leafs, fruit and seeds and is humid and dark (receiving only
2% of sunlight) but plays an important part in the forests ecosystem, it is
where decomposition takes place, fungi breaks down dead animals and plants and
then recycles nutrients and materials. The canopy can sometimes reach heights
of up to 30m above the ground and consists of overlapping leafs and branches
from trees, scientists estimate that between 60-90% of life found is found in
the canopy of the rainforest (Mongabay,
2004) animals such as
birds, monkeys, snakes and lizards. The canopy has a much different environment
to the forest floor, it is a lot hotter and drier forest floor during the day
and provides sources of food and shelter. The rainforest has a high level of
rainfall due to the high humidity, the rain in this particular biome is also
most often recycled rain, the heat during the day causes water to evaporate in
the air which then form clouds above the Congo’s canopy which then release
water in the form of rain back into the rainforest (Bioexpedition,
2013) as a result of
this the Congo has the second largest river in the world i.e. the Congo River
which drains an area of 3.7 million square kilometres known as the Congo Basin,
this is another reason why the Congo is so bio diverse as well as a high
diversity of terrestrial species it also has a high biodiversity of aquatic
species (Mongabay, 1994).
The Congo River
Figure 5 showing the Congo river . Source:http://congoconference2011.wordpress.com/category/a-brief-history-of-the-congo/
Species Population
There about 6,000 plant species in the tropical rainforest biome, major forest species of plants include Venus fly traps, ferns, orchids, and Kapok trees also Bromeliads. The canopy of the Congo consist largely of African oak, Red cedar and mahogany , as only 1% of sun reaches the forest floor tall growth is necessary for competition of light , Lianas and Ficus are climbing plants which send their shoots through trees in order to obtain more sunlight.
The forest floor
contains small ferns and decomposing leaves due to plants not being able to
survive due to the lack of sun however the forest floor is still an important
part of the Congo as the decomposition of dead material that occurs on the forest
floor helps to provide the nutrients that all other plants need to survive
enabling a healthy canopy un the rainforest therefore providing a habitat for
the thousands of species that live there ( weebly Congo rainforest, 2015).The
Congo consists of a huge variety of flora and with such competition for the
same resources it’s important that the Congo flora adapts to their surroundings
in order to survive for example roots of flora. In order to be able to support
trees of huge heights roots rely on an alternative to depth this is due to
rainforest soil retaining nutrients in the top layer therefore requiring that
trees use a shallow root system to provide the needed resources (Gcse bitesize,
2014).
Buttress roots
grow from the ground up the side of the tree of a height of 2 metres or more
and help to anchor the tree to the ground.
Figure 6 showing examples of Buttress roots.
Source:http://www.bbc.co.uk/schools/gcsebitesize/geography/ecosystems/tropical_rainforests_rev4.shtml
Another adaption of the flora is thin bark, trees in the rainforest have no need to trap moisture with thick bark, as a result of the high humidity the trees actually tend to have thin bark which allows moisture to escape from the trunk, also there is a low risk of parasitic plants being able to grown on the trunk due to the soft texture of bark (Ehow, 2015) The rainforest is also the home of many medicinal plants, on average over 7,000 medicinal products prescribed by doctors originate from plants found in the Congo, some examples are…
The Trumpet Tree- all parts of the tree, flowers, bark, leaves, roots and fruit are used to treat rheumatism and respiratory illnesses
Mammosa-is used to treat sinus infections and lesions formed by skin cancers, it is a member of the eggplant family
Periwinkle-is used widely to treat leukaemia and Hodgkin’s disease
Cinchona Tree- Quinine is extracted from the bark and used to treat malaria
Lemongrass-has anti-bacterial properties which aid in helping, coughs, fevers and colds, it is also a popular herbal tea.
Cocoa Tree- this is classed as one of the most important rainforest plants due to it producing over 150 chemicals that can be removed from its leaves , bark fruit and seeds, the extracts are then used to help treat coughs, kidney stones, cuts, bruises,, anxiety, fever and fatigue.
There is an
extremely high biodiversity of fauna (animal life) in the Congo, the animals
have adapted the rainforest as their habitat and live at different levels in
the forest for example birds in the canopy and mammals on the forest floor and
they all encounter fierce competition for everyday survival. Some examples of
the Congo’s inhabitants are...
Poison Dart Frogs-they are brightly coloured and have
poisonous skin, they feed on small insects like spiders and flies.
Figure 7 showing
a poison dart frog
Monarch Butterfly-are poisonous butterflies that
feed on milkweed plants and have bright coloured wings, if they are eaten their
predators become sick due to the poison.
Figure 8 showing a Monarch butterfly. Source: http://blog.mysanantonio.com/monikamaeckle/2010/10/how-to-tag-monarch-butterflies-a-timely-question-as-peak-migration-nears/
Anaconda-is the largest snake in the world
and is mostly found in swamps and marshes, it can go without food for almost a
year after feasting on a big prey. It feeds on pigs, deer, birds, etc. and
hunts mostly at night.
Figure 9 showing an
anaconda snake. Source: http://commons.wikimedia.org/wiki/File:Anaconda_Loreto_Peru.jpg
Capybara- are the largest rodents and found
in swamps, marshes and rivers, they feed on tree bark, fruit and aquatic plants
and are found in large groups. They are preyed by anacondas and jaguars.
Figure 10 showing a Capybara.Source:http://animalz-lover.blogspot.co.uk/2013/04/Capybara-Amazing-Facts.html
The diversity of the Congo is so huge and is inhabited by some of the greatest species on earth such as giant mountain gorillas and various types of elephants, chimpanzees, jaguars, wild boars and white rhinos. Kingfishers, macaws, hornbills and toucans are the most found bird species.
There are many
large animals in the rainforest that are endemic to the Congo which means they
only live here and nowhere else, some examples being...
Congo Clawless Otter- which is extremely endangered.
Figure 11 showing a
clawless otter. Source:http://otter-news.blogspot.co.uk/2013/03/cape-clawless-otter-status-and.html
Okapi-is a relative of the giraffe and
found only in zoos
Forest Elephants-their population has decreased 80%
in the last 50 years
Manatee-their only real threat is hunting
and loss of habitat by man
Eastern Lowland Gorillas-are the world’s largest primates
but about 300 are killed every year for “bush meat” and is the primary threat
to the ape populations.
Bonobos- a type of chimpanzee and one of
humankind’s closest living relatives
(Ehow, 2014).
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