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week 7 Biodiversity

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BIODIVERSITY
Biodiversity is a term used to describe how varied living things are in an ecosystem. The more
diverse the ecosystem, the more stable it is.
Biodiversity is used describes how diverse organisms in an area. It is a measure how many
different species live in an area. An ecosystem with high biodiversity has many different species of
organisms. An ecosystem with low biodiversity does not have many different species of organisms.
Biodiversity is the variety of life forms in an ecosystem that describes how varied living things
are in a specific area. It is very important since it sustains through the flow of energy the food web
on earth and contributes to environmental stability.
Biodiversity is the variety of life on earth and the essential interdependence of all living things.
Biological diversity, includes all organisms, species, and populations; the genetic variation
among these; and all their complex assemblages of communities and ecosystems. It also refers to
the interrelatedness of genes, species, and ecosystems and their interactions with the environment.
An ecosystem can be small like an aquarium or a small pond in your backyard, with only a few
organisms interacting, or it may be large, like a forest with lots of organisms interacting. There are
two types of ecosystem: man-made and natural ecosystem. When we speak of natural ecosystem, we
are referring to those areas with little or no human intervention. A forest is a natural ecosystem if it
remains to be unchanged by human activities. Other natural ecosystems include the oceans, the
seas and the rivers.
Organisms are part of biodiversity and may be economically and ecologically valuable. Their
products are a source of food, medicine, clothing, shelter and energy. They are important in
maintaining the balance in the ecosystem as they perform their specific roles.
Biodiversity describes how various are organisms’ existence in different ecosystems. Organism
can be economically and ecologically valuable. These organisms are also essential in keeping the
ecosystem stable as they perform their specific roles.
Biodiversity is vital as it sustains through flow of energy the food web on this planet and
contributes to environmental stability. Stability of an ecosystem can be described as the resilience
to resist changes that will occur in the environment. There are many changes that occur in the
environment, and these changes may severely reduce biodiversity and will result in instability of the
ecosystem.
The value of species can be divided into various categories:
1. DIRECT ECONOMIC VALUE
Species are sources of the basic needs of human such as, food, clothing, shelter,
medicine and energy. For example, rice plant is the primary food of Filipino. Cotton is
use to make clothes. Malunggay rich in vitamins; it is used to make medicines.
2. INDIRECT ECONOMIC VALUE
Species if there are benefits produced by the organism without using them. For
example, tree planting to prevent landslide and soil erosion and absorbs carbon dioxide
in the air.
3. AESTHETIC VALUE
Lot of species provides visual or artistic enjoyment, like forested landscape and
the calming beauty of a natural park; or they may be used for spiritual meditation like
the Prayer Mountains.
LEVELS OF BIODIVERSITY
1. Genetic Diversity - different genes & combinations of genes within populations.
Genetic diversity is all the different genes contained in all individual plants, animals,
fungi, and microorganisms. It occurs within a species as well as between species.
2. Species Diversity- organisms that have the potential to interbreed in nature and
produce viable, fertile offspring. A number of different species represented in a given
community. Population are a group of individuals of the same species that live in the
same area and interbreed, producing fertile offspring. Species diversity is all the
differences within and between populations of species, as well as between different
species.
3. Ecosystem Diversity-variation in the ecosystems found in a region. Ecosystem
diversity is all the different habitats, biological communities, and ecological processes,
as well as variation within individual ecosystems.
Species diversity is defined as the number of species and abundance of each species that live
in a location. The number of species that live in a certain location is called species richness. Species
diversity is the number of different species that are represented in a given community. Species
diversity is the number of different species that are represented in a given community (a dataset) incorporates both the number of species in a community (species richness) and the evenness of
species abundance. The effective number of species refers to the number of equally abundant species
needed to obtain the same mean proportional species abundance as that observed in the dataset of
interest.
Species is described as largest group of organisms capable of interbreeding and producing
fertile offspring. Diversity as a state of being diverse or variety; a range of different things.
3 TYPES OF SPECIES:
Endemic species - is one whose habitat is restricted to a particular area; often
endangered - differs from “indigenous,” or “native,” (although it occurs naturally in an
area, is also found in other areas.)
Exotic Species -is any species intentionally or accidentally transported and released
by man into an environment outside its present range. -most severe agents of habitat
alteration and degradation, and major cause of the continuing loss of biological diversity
throughout the world.
Cosmopolitan Species -Pertinent or common to the whole world. Cosmopolitan
distributions can be observed both in extinct and extant species.
In an ecosystem, there are various interactions between species that contribute to the
structure of the community. This interaction may be categorized into four types: competition,
predation, herbivory and symbiosis.
Adaptation refers to the ability of an organism to survive and reproduce in an environment.
This may involve changes in behavior or physical structure to survive. For example, if we take a
street dog (that lives in a tropic place) in Alaska (cold country), it will grow thicker fur to survive cold
temperature. Likewise, when a dog in a cold country brought to the tropics, it will shed its fur to
adapt to the warm climate.
Variation increases the chance of survival. Organisms with the most desirable traits would
likely survive environmental changes and gradually become better suited to survive in a given
environment; this is called adaptation.
The differences among individuals in a population that improve the species' fitness. These
adaptations can be physical, chemical, or behavioral. Camouflage and mimicry are two forms of
physical adaptation.
Camouflage: Structural adaptation that enables an individual to blend with its
surroundings, and that allows an individual to avoid detection by predators. Occurs
when an individual “blend” into the environment in the eyes of a potential predator.
Mimicry: A phenomenon in which an individual gain some sort of survival advantage
by looking like an individual of another (often more harmful) species. Is present when
one species has evolved to look like another species in a way that will provide some
advantage. The best-known examples of mimicry are those in which a species mimics
another that is toxic or harmful to a potential predator.
Camouflage and mimicry are both adaptations because they increase the
likelihood of an individual evading predation long enough to reproduce.
Bivalves also provide good examples of camouflage and mimicry. The spines on
the shells of Spiny Oysters (family Spondylidae) provide crevices in which algae,
sponges, and other epibionts
Epibiont is an organism that lives on the surface of another living organism. Can
settle and grow to cover and camouflage the shell. With time, this growth helps the Spiny
Oyster to “disappear” on the surface of the reef, lowering the threat of predation from
top level predators such as fish. Octopuses and squid (both cephalopods, and close
relatives of bivalves) are the “camouflage champions” of the mollusk.
In an article published by usaid.gov. bwiser, 2016, Philippines is considered as one of the 17
mega biodiverse countries in the world containing 2/3 of the Earth’s biodiversity and 70% of the
world’s plants and animal species. It is geographical isolation with an area of 300,000 square meters
and tropical climate made it a perfect place to inhabit a variety of life forms.
The two basic reasons why a population’s size increases, or decreases are the birth rate
(natality) and the death rate (mortality). If the birth rate is greater than the death rate, a population
will increase. If the birth rate is slower than the death rate, the population will decrease.
A population is a group of living things within a certain area that are all of the same species.
Several different populations may be found in a community. Populations can be of the same size but
they may have different densities. Population density is defined as the number of organisms per
unit area.
A major component of modern ecological research focuses on understanding what influences
the abundance of organisms within a population, and why this abundance changes over time.
A term called population dynamics refers to how populations of species change over time. The
study of a species’ population dynamics usually seeks to answer questions such as:
What explains the average abundance of a population?
What causes fluctuations in the abundance of a population?
When conditions are ideal for growth and reproduction, a population will experience a rapid
increase in size. Initially the population grows slowly, but the larger the population gets, the faster
it grows. As more offspring survive and reproduce, even more offspring are born. The graph illustrates
a population growth curve of this nature.
Population Growth Curve
Population growth is based on four fundamental factors: birth rate, death rate, immigration,
and emigration.
Using these factors, the formula in determining population growth is as follows:
Population growth= (births+ immigrants) - (deaths+ emigrants)
If the population growth is less than zero, this simply means that there are more deaths and
emigrants (organisms that leave the area) in the population than there are births and immigrants
(organisms that arrive new to the area). If this is the case, the size of the population will begin to
decline.
Ecologists regularly monitor the number of organisms in many populations because every
population can either potentially grow or decrease. They also observe the indicators that manifest if
some potential problems in the habitat of the organisms may arise. Each condition will give a warning
to the ecologists if something is off.
An essential question though is why do population sizes have a tendency to increase or
decrease?
There are many factors that can cause a population’s size to change and this is the reason
why there is a need to understand the basic reason why a certain population increases or decreases.
Population of any organisms (humans, animals or bacteria) will continue to grow if more organisms
are being developed (genetically modified organisms) or born, than are dying.
There are two main ways that individuals can be added to the population.
The first way is through the births of new individuals. The way we measure additions
of this type is with the natality rate (also called the birth rate), which is the number of
births per 1,000 individuals per unit of time, usually per year.
The second way in which individuals are added to the population is through
immigration. This is the permanent arrival of new individuals into the population. These
individuals are of the same species as the rest of the population, and they can increase
the size of the population as they join the group.
On the flip side, we have two main ways that individuals can leave a population and reduce
its size.
First is through the deaths of individuals. We measure this with the mortality rate
(also called the death rate), which is the number of deaths per 1,000 individuals per
unit of time. Again, this time is usually measured by year.
Second, individuals may leave through emigration. This is the permanent movement
of individuals out of a population. These may be juveniles who are heading out on their
own, or it may be adults leaving the group for some other reason such as overcrowding
or searching for new areas for food and shelter.
Take note that if the birth rate is greater than the death rate, a population will
grow. On the other hand, if the death rate is greater than the birth rate, then
the population will decrease.
The largest population of a species that a particular environment can support is known as the
CARRYING CAPACITY. The carrying capacity of the environment varies at different times. Sometimes,
when resources such as food and water are more abundant, a population can increase in size. At
other times, when there is less food, water, and shelter, a population can decline.
These population fluctuations occur over time, but the carrying capacity represents an
average series of ups and downs. If you draw a line through the middle of the population fluctuations,
that line represents the carrying capacity of that environment for species living in it.
As a population grows in an area, a population may experience the effects of increased
densities. The maximum population size of species that the environment can sustain is called the
carrying capacity which is determined by the amount of available resources (food, habitat, water).
In a high population density, there are a lot of organisms crowded in a certain area, while in
a low population density, only few organisms are in an area. Differences in population densities in
any community may be attributed to limiting factors.
Limiting factors limit the size of a population. These factors prevent the growing population
of any organism in an area, which will be limited, or stopped at some point. Limiting factors are
categorized into two: the density-independent limiting factors and density-dependent limiting
factors.
Ultimately, when a population grows, it does not grow forever. It will stop at some point, until
eventually, the death rate will exceed the birth rate. Basically, the population’s growth is limited by
two general factors: density-independent limiting factors and density-dependent limiting
factors.
If the population’s density does not directly influence changes in population
growth, then it is called a density-independent limiting factor. Examples include
natural disasters like tropical cyclones, floods, earthquakes and fires. These natural
phenomena will stop a population from growing no matter how many organisms are
living in a certain place. The same goes for the temperature of an area and the amount
of sunlight it receives. If the temperature increases due to global warming, this will
cause a decrease in a population’s numbers, no matter how large or small the population
was to begin with. Human activities that alter the environment will also decrease the
number of organisms in a population, regardless of the size of the population.
Density-independent factors, such as temperature or natural disasters, refer to
any influences on birth or death rates regardless of the population density (the number
of organisms per unit area). If a population’s density is very high, that means there are
a lot of organisms crowded within a certain area. If a population’s density is low, this
means that there are very few organisms found in an area.
Density-independent limiting factors that can stop a population from growing can
be such things as natural disasters, temperature, sunlight, and the activities of humans
in the environment. Natural disasters such as tropical cyclones, floods, earthquakes
and fires will stop a population from growing no matter how many organisms are living
in a certain area.
As an example, global warming is proven to increase the temperature of an area
and the amount of sunlight it receives. This phenomenon can cause a decrease in a
population’s number, regardless of how large or small the population was to begin with.
This simply means that human activities that alter the environment, global warming for
example, can definitely decrease the number of organisms in a population regardless of
the size of a population.
A factor that regulates a population’s growth and is influenced by population
density is called density-dependent limiting factors. Density-dependent limiting
factors come into play when a population reaches a certain number of organisms. For
example, when a population reaches a certain size, there will not be enough resources
(food, shelter, water) for all the organisms. This could cause the population to stop
growing when it reaches the maximum number of organisms that can be supported or
“carried”, by the environment. This number is known as the population’s carrying
capacity in a particular environment. Each population of organisms has a different
carrying capacity, depending on the amount of resources available in the area in which
it lives.
Density-dependent limiting factors, however, are tied to population density. In
other words, they change how they can affect the population as the population changes
in size. These factors can be biological in nature, such as food, shelter, or other limited
resources. This will come into play when the population reaches a certain number or
organisms and there is a lack of enough resources (shelter, water, food) for all the
organisms.
Density-dependent limiting factors are factors that depend on the size of a certain
population. If the population is already high, these factors will limit the increase of
population size. Such density-dependent limiting factors are the availability of food,
water, and space. While density-independent limiting factors are those that limit the
size of population regardless of the population number. Some examples are natural
disasters, temperature, and sunlight.
This event can cause the population to stop growing when it reaches the maximum number
of organisms that can be supported by the environment. This number is known as the population’s
carrying capacity in an environment. Each population of organisms has a different carrying capacity
depending on the amount of resources available in the area in which they live.
Each population of organisms has a
different carrying capacity depending on the
amount of resources available in the area. There
is a limit to the number of individuals in a
population that an environment can maintain.
Before a population reaches it’s carrying
capacity, it experiences a period of rapid growth.
This period of growth is called exponential
population growth. During this period, there
are plenty of resources available for all
organisms, so more births are recorded than
deaths of organisms. When resources are
unlimited, populations exhibit exponential
growth, resulting in a J-shaped curve.
When resources are limited, populations
exhibit logistic growth. This is a description of
idealized population growth that is slowed by
limiting factors. When resources are limited,
populations exhibit this type of growth. In
logistic growth, population expansion decreases
as resources become scarce, and it levels off
when the carrying capacity of the environment
is reached, resulting in an S-shaped curve.
Limiting Factors that Depend on
Population Density
Illustration
Diseases and parasites- infectious diseases
and parasites spread faster in densely
populated areas.
Competition for resources- organisms with
better adaptations to obtain (food) resources
will be able to reproduce more often, and its
population will grow. The organisms that
have limited abilities to compete for the
resources will not reproduce as often, may
not be fit enough to live long, and can cause
their population to decrease.
Predation- plenty of prey are available,
predators will be able to eat sufficiently, thus
have energy to reproduce much, and increase
their numbers. The population of the prey
will begin to decrease as more and more of
them are eaten. However, the predator
population will eventually reach carrying
capacity-there will not be enough prey for all
of the predators in the population, since the
predators themselves compete for their “prey”
resources. As the number of prey decreases,
so will the number of predators because there
is not enough food to sustain them.
Emigration- It occurs when a population
approaches its carrying capacity, and
individual organisms leave and go to a new
area where they can find enough resources
for survival and reproduction. This will
obviously cause decrease in the amount of
organisms in a population.
Organisms need a balanced ecosystem. Their number should not exceed in the carrying
capacity of their respective environment. This is called sustainable development.
THE MEASUREMENT OF BIODIVERSITY
Biodiversity is The sum of all biotic variation from the level of genes to ecosystems.  The
number, variety, and variability of living organisms in a quantified area.
Methods to Measure Biodiversity:
 Species Richness - the total number of given species in a quantified area.
 Species Evenness - the degree to which the number of individual organisms are evenly
divided between different species of the community.
 Disparity - measures the phenotypic differences among species resulting from the
differences genes within a population.
 Species Rarity - the rarity of individual organisms within a quantified area.
 Genetic Variability - each population of a species contributes to additional biodiversity
due to variations between genes.
Biodiversity and the Relationship to Ecosystem Functions
- Diverse communities are typically more stable and function more efficiently.
- Increase of productivity in an area corresponds with an increase in biodiversity
- Ecosystems with high measures of biodiversity are more resistant to invader species.
• Biodiversity is the variety of life and can be measured on multiple scales including genetic diversity,
species diversity, and ecosystem diversity.
• Indices that measure species diversity include species richness (the number of species in a given
area), the Shannon diversity index (accounting for richness and proportional abundance of
species) and evenness (similarity in the abundances of species).
• The location and abundance of animals are determined by the availability of resources and
community interactions, such as competition, predation, and human influences.
• An ecological niche is the role of an organism in its environment, which includes the conditions
under which it can live, what resources it uses, and how it reproduces.
• The diversity of an ecosystem, including soil, plant, structural, topographic, and climatic diversity,
can positively impact animal species diversity.
Threats to Biodiversity and their Implications
Biodiversity around the world is threatened by pollution, climate change, and
invasive species. A main underlying reason for efforts to maintain biodiversity is based
on ecosystem functioning. Ecosystems are made up of many working parts, including
primary producers, herbivores, carnivores, and detritivores, all of which contribute to
ecosystem function. If species are lost, the ecosystem may collapse. And if the ecosystem
collapses, the services that it provides to humans will as well.
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