Portfolio Extracurricular Tasks In Biology
-by Roko
1. Theory of Evolution – Variation and Selection
2. The principle of causality and the scientific method
3. Ecological balance and ecological stability
Encyclopedia of basic biological concepts
1.)
Roko Kovic 2dN
Theory of Evolution – Variation and Selection
Evolution is an extremely popular, widespread theory which in itself holds up down to the
present day irrefutable arguments of how all the different variations of plants and living
organisms were formed since the beginning of life on Earth. Even though it has answers for a
lot, it is only theory, which is speculation. Our earth is estimated to have an age of 4.5~4.6
billion years. But the first signs of life appeared after 1 billion year passed. How or when
exactly the first life-forms appeared is unknown. There are also theories for that; life came
from outer space, an asteroid which contained some extremely basic form of bacteria landed
in the sea, which then seemed to be a perfect place to start life. Another theory is that all life
forms came from swamps, while others say bacteria came into existence directly in the
water. Some seem more and some seem less probable. After another 3 billion years the first
real life forms started to exist, which ever since then inhabited our world with vast varieties
of life-forms. Our knowledge of the first micro-organisms, which are our ‘ancestors’ or so to
speak, is extremely small. The oldest proofs of ancient life-forms are the fossilized remains of
these animals. These forces are variation and selection. These forces could be seen as a
struggle to exist. Variation is for example; when rats reproduce, the mother rat gives birth to
more newborns than can survive. A few of or maybe even one of them has a slight alteration
to his body. Maybe he is a little bigger, has longer legs, changed his fur color partially, etc. If
that alteration then proves to be useful in surviving, useful in a certain environment, this rat
will survive easier. Then if it is fully grown up it will reproduce again, the changes it carried
within its body will be passed on to the new generation. But if the alteration was a mistake,
the rat can die easier. Evolution is a game of trial and error. Variation is much more common
in sexual than asexual reproduction, for the new genes are a half and half mix of the mother
and the father cells. Asexual reproduction doesn’t really have ‘normal’ variation, but those
variations are rather mutations. An example would be a lizard type which mostly bears
females as newborns, males are obsolete. This phenomenon is called Parthenogenesis.
Natural selection is when favorable traits which are heritable for future generations become
much more common after a new generation is born. Every generation can have specific traits
or ‘abilities’ which were only needed for a part of the generation’s life.
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Encyclopedia of basic biological concepts
2.)
Roko Kovic 2dN
The principle of causality and the scientific method
Causality is the relationship between two events. The first event is the cause, the second
event is the effect. The second effect is an implication of the first one. This also is called
Cause and Effect. But most commonly causality is also the relationship between a set of
factors (also causes) and a phenomenon (the effect). There also can be additional factors to
that sometimes. These factors are active factors, something that is not a permanent
condition, like weather. In science this is needed a lot. One example is observing. Scientists
can observe the behavior of different types of animals and see how they react to their
environment. What do they do with obstacles in their way? What are they feeding on? What
makes them afraid, jump back? We humans used this for a long time. We can learn
something just by observing it, studying it. It helped us gain intelligence. Quite some animals
exist which really have social ranks under their selves, this has been discovered while
observing animals. The prairie dog even has its own ‘language’. It uses differently pitched
sounds to give messages to other fellow prairie dogs. They alarm each other if they see an
enemy. They give out messages to retreat, etc. This is mostly an observation. Another
example for this is the butterfly effect. When all conditions are met, which is relatively rare, a
single flap of a butterfly’s wings can cause a chain reaction which in the end leads to a
tornado. The power or the force behind a tornado is usually quite high. Even though a
butterfly flap is barely noticeable, within the right conditions, it can be an initiation to a
disaster. The flap of a butterfly creates tiny changes in the atmosphere, which can be
powered op to gusts of wind and a lot of other factors. Apart from observing experimenting
is also a possibility. When experiments are conducted, the factors which are influencing the
animal are not random, but chosen precisely. With that, information is a lot easier to be
acquired, but the behavior of the animals may not be the one it has in its natural habitat. It is
possible that an animal feels scared, or shy, in a place it has never been before. And the
reactions it has to everything can be drastically different. The observing method without
direct interfering to the factors, gives slower or less, but more exact results than the
experiments. The observing method is more animal-friendly than the experiment method.
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Encyclopedia of basic biological concepts
3.)
Roko Kovic 2dN
Ecological balance and ecological stability
The Ecological Balance is a state of dynamic equilibrium within a community of organisms in
which genetic, ecosystem and species diversity remains the same. There is a relatively stable
balance between multiple species of animals and plants. There are multiple relationships per
ecosystem. One of these relationships is the Predator-Prey-Relationship. A predator (mostly
carnivore) is an organism that survives by consuming/eating another organism. The prey is
the organism which is eaten by the predator. This system does not only work when an
animal eats an animal, but also when an animal eats a plant, for example; a lion and a zebra, a
rabbit and lettuce. Predator and prey evolve together. The predator is part of the prey’s
environment, and the prey is part of the predator environment. The predator’s try to evolve
with the abilities needed to be able to catch the prey, to bite the flesh off, to digest the prey,
etc. And the prey also tries to evolve with abilities needed to hide from predators, run away
from them, and scare them away and so on. In the end all it is, is a race to see whose traits
and abilities are superior to the other one. Who has adapted better to the environment? Who
has special methods of defense, an example is the hedgehog with its spikes. There is almost
always more than one factor the animals need to adapt to. And only those which succeed in
surviving pass on their skills. This can also be seen as quote unquote survival of the fittest.
An example for number related questions is a simple Predator-Prey-Relationship. If there
are a lot of prairie dogs, the numbers of their predators, eagles also starts to increase. The
high number of eagles, which all feed on prairie dogs, leads to a smaller prairie dog number.
This smaller prairie dog number makes a lot of eagles starve, and this decrease of eagles
makes the number of prairie dogs rise again. This is a circle of life that repeats itself over and
over. An ecosystem is somewhat comparable to a hierarchy. I will show the food net of the
prairie.
On top is the King/eagle.
Below him are Noblemen/ rattlesnake/ burrowing owl/ ferret/ badger/ coyote/ swift fox.
Below these are the Lords/ prairie dogs/ bison/ pronghorn antelope/ rabbits/ insects.
The lowest are the Peasants/ bison grass/ scarlet globemallow/ fetid marigold/ snow-onthe-mountains
All of these relationships and proportionalities make an ecosystem stable. The predators
regulate the prey number, and the prey regulates the predator number. If an intruder
manages to enter and live in an ecosystem, that system can become unstable. If this intruder
is a predator, it could feed on the prey living there. But if this intruder is strong enough, or
the prey has not accustomed to it or them yet, they could all get eaten and could go extinct.
And the ecosystem could also crash if some factor vanishes or gets removed. Ecosystems are
fragile and strong at the same time.
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Encyclopedia of basic biological concepts
Roko Kovic 2dN
Picture Sources.: Nasa ISS017E0116998
Foctulus.de
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