Biodiversity
Biodiversity is the total variety of living things in an
particular area. The more biodiversity that is present in an
ecosystem, the healthier it is.
This biodiversity, or variety, makes it more likely that an
ecosystem remains healthy, particularly if changes to the system
occur. If there are
a variety of species in an area, each having slightly different
traits and abilities, the odds would be pretty good that
life would be able to survive if something about the ecosystem
changed. We see changes in ecosystems all the time caused
by droughts, climate, and the availability of resources such as
clean soil and water.
We'll learn a bit more about the value of this Biodiversity, and
how we might all try to preserve
Biodiversity in Earth's ecosystems a little later on. But
first...
In order to understand the value of biodiversity, it makes sense
to begin with how scientists keep track of all the various
species here on Earth.
SCIENTISTS CLASSIFY MILLIONS OF SPECIES:
400
years ago, scientists who studied insects classified them
based upon their
appearance and
behavior. If animals looked alike, researchers concluded
that they were related.
In the 1600’s much exploration took
place. New inventions, like the
microscope, allowed us to see animals in a detail never
before
possible.
CLASSIFICATION VS. TAXONOMY
Classification-
the process of arranging organisms into groups based upon
similarities and differences.
A
good system allows you to organize a large amount of
information
so it is easy to find and understand.
Taxonomy-
is the science of naming and classifying organisms.
A
good system of taxonomy allows people to communicate about
organisms using the same
language. Similar organisms have
similar names.
Taxonomists also study biological relationships. A
TAXON is a group
of organisms that share certain
traits. These taxons can be
broad, like “animals”, or quite
specific, like “cats” or “roses”.
Taxonimists also study the relationships between
species, trying
to discover how one species evolved
as compared to other
species. They also try to find
relationships among species to
see if they’re related or connected
in some way.
Species that share
ancestors are grouped together.
USING CLASSIFICATION:
To classify organisms,
scientists use similarities and differences among
species.
Generally, these similarities and
differences are things that
are visible, or measurable.
External Features: Size, weight, fur, feathers,
scales, color, shape,
body parts, way of feeding, habits,
habitat, food.
Internal Features: Organs, DNA, cells and cell
structure, method of
getting energy, method of
reproduction.
To
determine how to classify organisms, scientists compare a
variety
of characteristics, or traits.
A “TRAIT” is a characteristic or
behavior that can be used to tell two
species apart, such as
size or bone structure. If two
organisms share a trait,
taxonomists try to determine if they
share the trait
because they share an ancestor.
Taxonomists take evidence and also try to reconstruct
the evolution
of a species
BIOLOGISTS USE SEVEN LEVELS
OF CLASSIFICATION:
KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS
SPECIES
SAMPLE FOR
A CAT:
KINGDOM:
ANIMALIA
PHYLUM:
CHORDATA
CLASS:
MAMMALIA
ORDER:
CARNIVORA
FAMILY:
FELIDAE-THE CAT FAMILY
GENUS:
FELIS-HOUSECATS, COUGARS AND MANY OTHERS
SPECIES:
CATUS-ALL HOUSE CATS, NO MATTER WHAT THEIR BREED.
Like the cat, the turtle
is also classified into seven levels.
However, only the largest categories, Animalia and Chordata,
are the same as the classification for a house cat.
The more
names an organism shares with another organism,
the more closely related the two organisms are.
Spotted Turtle:
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
(turtles)
Family: Emydidae (water
turtles)
Genus: Clemmys (north
american pond turtles)
Species: guttata
(the spotted turtle)
Human:How
closely are humans related to cats?
How about to turtles?
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: sapiens
Dichotomous keys and field guides help people identify
organisms.
With millions of
organisms on Earth, how could one specific one be
identified?
Even if you know the larger categories, it can still be
difficult to find the species, genus or even the family name.
Take a beetle for
example. Even if you knew it was in the Kingdom
Animalia, Phylum arthropoda (animals with jointed legs) and
order Coleoptera (hard winged insects), you’d still have to
choose among 300,000 known species of beetles that have been
discovered in the world..
Taxonomists have come up with a tool to help, called a
Dichotomous Key. These keys ask a series of questions that
can only be answered in two ways. Your answer to each
question leads to another question. After a number of
questions, you’ll eventually identify the specific organism
you’re looking at.
The questions in a Dichotomous Key gradually narrow down the
list of possible organisms.
FIELD GUIDES are another
tool for identifying organisms. They include pictures or
paintings of species. Flower guides may start with the
flower’s color. Bird guides are often arranged by orders
and families of birds. Field guides also usually include a
map showing where the organisms live.
The Six
Kingdoms:
As
a result of all this work
through the years by
Scientists , studying and
attempting to classify all
the living
things on Earth they
encounter, a system was
developed to help describe
the life forms they've
discovered,
and even more importantly
to begin to understand how
these life forms are
related to living things
today in from the past.
Most scientists agree that
there are six major types
of life on Earth.
These are called the
Kingdoms of Life.
Every single living thing
on Earth (that we've
discovered so far) will
fit
into these categories.
An Overview
Planate: The Plant Kingdom includes
plants such as trees, grass and moss.
They are multi cellular and live on land.
Plants obtain energy from sunlight.
A plant cell has a nucleus, cell wall and chloroplasts.
Animalia: The
Animal Kingdom contains animals, from lions, and tigers and
bears to bugs
and multicellular microbes.
Animals are multicellular and able to move.
Animals obtain energy from eating food.
An animal cell has a nucleus but no cell wall or chloroplasts.
Protista: The
Protist Kingdom contains organisms that don't easily fit into
animals, plants or the fungi kingdom.
They are either unicellular organisms or have a simple
multicellular structure.
Most protists are single celled.
Multicellular protists lack complex cell structures.
A protest cell has a nucleus.
Fungi: The
Fungus Kingdom includes mushrooms, molds and yeasts.
All fungi except yeasts are multicellular.
Fungi obtain energy by absorbing materials.
A fungus cell has a nucleus and a cell wall, but no
chloroplasts.
Archaea:
(Ahr-kee-uh)- The Archaea Kingdom contains organisms
that are similar to bacteria,
but have a cell structure that is so different that scientists
separate
them into their own kingdom.
archaea are unicellular organisms without nuclei.
Archaea cells have different chemicals than bacteria.
Archaea can live in extreme conditions.
Bacteria: The Bacteria
Kingdom contains unicellular organisms with NO nucleus.
Bacteria are unicellular organisms.
A bacteria cell has no nucleus.
Bacteria reproduce by dividing in two.
Most bacteria are actually pretty valuable and necessary
to live on Earth. Some bacteria of course are NOT so
valuable to humans, causing disease and infection.
The Six Kingdoms:
In a
little more detail...
The two most familiar kingdoms are plants and
animals:
Plantae:
250,000 species live on Earth.
They range from tiny
mosses to the largest organisms on Earth, giant
sequoia
trees.
The oldest living organism
on our planet is the Bristlecone Pine. Some
Bristlecone pines were growing when the Egyptians built
the
pyramids, 4000 years ago.
All plants are multi-cellular and eukaryotes,
which means their DNA is stored in a
nucleus
of their cells. All plants are able to make sugars using
the
sun’s energy. Plants cannot move from one place to
another,
but
they can grow around objects, turn towards light, and grow
upward.
Plant
cells are different from animals cells because they have tough
walls outside their cell membranes.
Animalia:
Scientists have already named a
million species in the animal kingdom. Many
different types of animals
inhabit the planet, but more than 90% of the
named species are insects.
All animals get their
energy by eating other organisms or by eating food
made by
other organisms. Animals have the ability to move around
for at
least part of their lives. Most animals have mouths and
some
type of
nervous system. Plant and animal cells are both
eukaryotes, but animals have NO cell walls.
The other kingdoms are
mostly microscopic organisms.
Protista
includes a wide variety of
organisms. Most are unicellular. Protists that are
multi
cellular are too simple to
be classified as plants, animals or fungi. All
protists have large,
complex cells with a true nucleus (Eukaryotes). Some
eat other organisms like
animals do, some get energy from sunlight like
plants do. Some
protists resemble fungi, but they don’t have as many
specialized cells as
plants, animals or fungi.
Many protists live in pond water or sea
water. The largest of the unicellular species
are barely visible without
a microscope. However, large organisms such
as seaweeds are also
classified as Protista. Some seaweeds can grow
hundreds of feet in a
single year.
Kelp for example.
Fungi:
Fungi are usually divided into three groups, mushrooms,
molds and yeasts.
The trait that separates fungi from other
organisms is that they take in nutrients from their
surroundings instead
of eating other organisms or using sunlight to make their
food.
Most fungi have cell walls like plants.
Unlike plants, fungi act as
decomposers, breaking down dead or decayed material
into simpler parts that can be absorbed, or recycled by other
organisms.
Bacteria:
Bacteria live nearly everywhere on Earth.
This Kingdom includes organisms that cause disease and
spoil food,
but most organisms in this Kingdom are helpful members of most
biological communities.
All bacteria are unicellular organisms.
They have small, simple cells without a nucleus.
Most bacteria have a cell wall outside the cell membrane,
but this wall isn’t the same as the cell wall of a plant.
Bacteria reproduce by dividing in two, and can
produce
many new generations in a short period of time.
Archaea:
In the mid 1990’s a researcher studying
the genes of some bacteria
discovered a new group of organisms that
resemble bacteria in size and cell type,
but some species had very specific genetic
differences.
They decided to call these organisms Archaea.
They differ so much that now scientists
classify archaea in a separate Kingdom called
Archaea.
Archaea cells do not have nuclei. Their cell
structure is also different than bacteria.
Like bacteria, archaea live in many environments,
especially in the ocean.
They also live in some very extreme environments,
such as boiling mud near
geysers, hot vents at the bottom of
the ocean, salty ponds,
and deep under the sand.
Biodiversity
What is
Biodiversity?
A measure of all the
different species living in an ecosystem.
The "variety" or
living things in an area.
No-one knows exactly how many species live on
Earth.
So far, more than 1.7 million species
have been identified. Pretty much
everyone agrees that this number represents just a
tiny fraction of the total
number of species living on Earth. The actual
number is probably a hundred
times higher!
It's difficult to estimate the total biodiversity on
Earth
because many areas haven't been
thoroughly studied.
Some experts think that the deep oceans
alone could contain
10 million
new species!
Factors affecting biodiversity:
Area-
Within an ecosystem a large area will contain more
species than a small
area.
Climate- In
general the number of species increases as you move
from the poles
toward the equator. The tropical rainforests of
Latin America, Southeast
Asia and central Africa are the most diverse
ecosystems in the world.
These forests cover about 7% of the Earths' land
surface and contain
about half of the world's species.
Niche Diversity-
A
niche is a particular area in an ecosystem where an
organism can live.
The more niches available, the more
biodiversity. Simple. More places
to
live equals more creatures taking advantage of the
opportunity. (Think
about it, it's no different than people moving into an
area to take
advantage of houses that have been built, or house
lots cleared, or
apartments built...it's the same idea. If there
are more places to live, then
you can expect more living things to take advantage of
the opportunity.
Why is
it important? What's the value of
biodiversity?
Economic
Value- Many plants and animals and other
organisms are essential for
human survival. In addition to providing food
and oxygen, these
organisms supply raw materials for clothing, medicine
and other products.
Ecotourism- Basically, people will pay money to
experience nature
as it was intended to be.
Hunting, fishing, camping, hiking,
wildlife tours, whale watches,
None of these things would happen
without a healthy ecosystem.
Value to the
Ecosystem:
All
species in an ecosystem are connected to one
another. Species
depend upon one another for food and shelter. A
change that affects
one species will surely affect many others.
Keystone Species-
a species in an ecosystem upon which many other
organisms depend. Keystone
species influence the survival of
many other species in the
ecosystem.
The problem
is, we don't always know which species are keystone
species until
it's too late.
Gene Pool Diversity:
Genes
control the traits that all living things possess.
Different organisms have different traits, and
these "traits" or
characteristics
make it possible for living things to survive on
Earth. Traits allow all living things to adapt
to the
changes that often
occur on Earth. The more traits you have, the
better your chances are of being able to survive
these changes.
(Like changes in climate for example). All of
the genes in a population of living things is called
"gene pool
diversity", meaning a "variety" of genes in a
population. Generally speaking, the more variety
in the
gene pool, the
more chance that "someone" will have the necessary
traits to survive almost ANY change that might
happen. So
a diverse gene pool is a good thing, because it allows
the species to survive. Survival is a good
thing,
and definitely
one of the advantages of having a large amount of
biodiversity in an area.
Extinction of
Species
Hey,
it happens. Things change. Some organisms
will have what it takes to survive and others won't.
That's
just the way it goes. Sometimes, a species on
Earth is driven closer to extinction for a variety of
reasons, some of
which are discussed in the next section.
We've begun to try to prevent species from being
driven to extinction. It involves learning as
much about each
organism as we can, and working to eliminate things
that are causing problems for a species. It's a
big job, made
more complicated that we don't even really even
KNOW how many species are out there! There are
probably about
a
HUNDRED species we've never even seen for each one
that we HAVE seen, studied and named.
Endangered Species are
in danger of being driven to extinction. Their
numbers in the world are very low,
and if immediate action isn't
taken, they might not survive.
Threatened Species are
in trouble, and if things don't improve, their numbers
in the world will continue to
fall, and the entire species could
become Endangered.
Currently in Maine, 33 species
are currently considered either Endangered or
Threatened!
Causes of Extinction
Habitat Destruction-Many
human activities can have an impact on nature. One of
the most common results of human activities is the
destruction of a creature's natural habitat.
Roads, homes, farmlands, and cities
can all affect the local environment.
habitat
fragmentation-this
means that the habitat is broken into smaller sections, not
necessarily connected together.
Many creatures thrive on large tracts of land in
order to carry out their lives and thrive.
A
single ten acre piece of land is a better environment than
twenty much smaller pieces of land that make up ten
acres.
There's just no
substitute for wide open spaces.
Our world used to be loaded with such places, but as
humans have continued to colonize the planet and change it
to suit
their own needs, the natural
environments in the world are getting smaller and
smaller, becoming increasingly displaced by
the evidence of human habitation such as
cities, towns, roads, farms, private homes and even the
dreaded shopping malls.
Poaching-
this is illegal hunting, plain and
simple. Most poachers are not hunting illegally to
put food on the table for
for their families. For most
poaching, animals are hunted
for skin, fur, claws, teeth, horns. Or for
exotic pets, such as tropical
fish, parrots,
tortoises.
Endangered plants harvested for
houseplants,
other
endangered plants sold for medicine.
Pollution of
the air and water can
threaten living things as well.
Exotic Species otherwise known as invasive
species which are species
not native to the area may move in, or be carried in by
humans and
distrupt the
entire ecosystem. They may carry disease to which the
local animals and plants have no natural
resistance. They can quite simply
come in and just
"take over" often times having no natural enemies in the
ecosystem.
Protecting Biodiversity
Captive
Breeding
Laws and Treaties
Habitat Preservation