BIOLOGY
POWERPOINT SLIDESHOW
Grade 9 Science
BIOLOGICAL
DIVERSITY
Supporting Science Textbook Content while enriching the Learning Process in Junior High/Middle School
An interesting example of
biological diversity…

Alligators and the End of Dentures?!
The tooth fairy may be good at handing
out cash for lost teeth when we’re kids, but
human’s pearly whites are naturally only
replaced once.
 If we lose a bicuspid as adults, we’re in
trouble.




American alligators’ teeth can regenerate up to
50 times.
USC researchers have uncovered the cellular
and molecular mechanisms behind tooth
renewal in alligators.
When an alligator loses a tooth, latent stem cells
are activated triggering tooth development.

Researchers hope this discovery could
lead to tooth regeneration in adult
humans!
BIOLOGY
Concept Map
Shows the concepts
covered
within the framework
of this unit
Biological
Diversity
Grade 9
BIOLOGICAL DIVERSITY Slides Key Concept Categories
4 - 12
BIODIVERSITY - Types & Classification
13 - 15
ADAPTATIONS - Structures & Functions
16 - 18
NICHE
19 - 23
SURVIVAL
24 - 27
VARIATION
28 - 35
REPRODUCTION
36 - 39
DNA
40 - 46
GENETICS
47 - 54
BIODIVERSITY - REDUCTION
55 - 56
ARTIFICIAL SELECTION
57 - 59
BIODIVERSITY - PRESERVATION
Outline
BIODIVERSITY -
Ecosystem Diversity
“Biodiversity is the variety of species and ecosystems on the Earth and
the ecological processes of they are a part of.”
Living things interact with non-living (abiotic) and living (biotic) parts of the
ecosystems they share. As these abiotic and biotic factors vary from one ecosystem
to another, ecosystem diversity refers to these differences.
Variations between and within ecosystems around the world affect the types and
numbers of species that can live in each of these ecosystems.
To determine the biological diversity of an area, biologists use a measurement called a
diversity index. This compares the diversity of species in a certain area with the
total number of organisms in that same area, or ecosystem. It is primarily used to
check on the health of an ecosystem – a healthy ecosystem has a high diversity index.
BIODIVERSITY -
Ecosystem Value
Having variation in an ecosystem enables some of the organisms in that ecosystem
to survive because of their higher level of resistance and survival adaptations, when
certain species die off. This is important in order to maintain the ecosystem.
Sacrificing one part of the ecosystem to save the main parts is also necessary
sometimes.
This is why foresters might decide to burn one part of a forest to save the part of
the forest that they know will be able to survive other factors that are threatening to
destroy the entire forest.
Mountain Pine Beetle
Destroys pine trees by spreading a blue-stain
fungal disease as it bores through the tree.
The tree eventually dies.
BIODIVERSITY -
Species Diversity
A species is a group of organisms that have the same structures and can reproduce
with one another.
Species Diversity is the number of different species in a particular area (also
referred to as species richness ) weighted by some measure of abundance such
as number of individuals, or biomass. However, it is common for biologists to speak
of species diversity even when they are actually referring to species richness.
Another measure of species diversity is the species evenness, which is the relative
abundance with which each species is represented in an area.
bacteria
cowbird
red fox
tiger salamander
BIODIVERSITY -
Species Diversity
An ecosystem where all the species are represented by the same number of
individuals has high species evenness. An ecosystem where some species are
represented by many individuals, and other species are represented by very few
individuals has a low species evenness.
The most successful life form seems to be the insect. There are many
different species that can potentially help other species, like the Pacific Yew Tree,
by producing medicines.
Biological diversity is important for the health and survival of natural communities.
Taxol, found to be effective in
controlling different types of cancers,
is extracted from the bark of the
Pacific Yew Tree.
9B Review
Biological Diversity
 Why should we care?


Graphing Review
The future?
BIODIVERSITY -
Genetic Diversity
Genetic diversity, a form of biodiversity, is the variety of different
types of genes in a species or population. Genetic diversity refers
to certain variations between members of a population.
the banded snail
Genetic diversity is variation of individual genes, which provides an opportunity
for populations of organisms to adapt to their ever-changing environment.
The more variation, the better the chance that at least some of the individuals
will have a variation that is suited for the new environment, and will produce
offspring with that variation, so that they can, in turn, reproduce and continue
the population into subsequent generations.
With the interdependence between biological and genetic diversity; changes in
biodiversity result in changes in the environment, requiring subsequent
adaptation of the remaining species. Changes in genetic diversity, particularly
loss of diversity through loss of species, results in a loss of biological diversity.
9A Review
Biological Diversity
 Why should we care?


Graphing review
The future?
BIODIVERSITY -
Community Diversity
Community Diversity occurs within populations of organisms living within a
particular ecosystem.
Distribution - When individuals of the same species live within the same area and
share the same resources, a population of exists. When a number of different
populations share a common ecosystem, a community exists. Populations and
communities are not distributed evenly on the Earth. The pattern of distribution is
much the same as the overall biodiversity of our planet. More variety and numbers
of populations and communities near places where it is warm (tropical rainforests
and coral reefs) and less variety and numbers where it is cold (Arctic and Antarctic).
BIODIVERSITY -
Community Diversity
In northern Canada there are large populations of those species found there, but
there are not as many different plant and animal species as there are in other parts
of Canada. Large herds of caribou, polar bears, wolves and millions of arctic hare
make up the majority of the animals you will find.
The species of wolf, and polar bear are also found in Russia and northern Europe.,
Canis lupus,
Ursus maritimus
,
In contrast, hundreds of thousands of species (in small populations) can be found in
the rainforests of Central and South America. The reason that Canada supports
large populations, with less diversity is the extreme environment and seasonal
variations, which restrict their food supply. Organisms living in this ecosystem have
a broad niche with adaptations that enable them to survive the extreme changes
occurring there. These species are considered to be generalists – able to spread
over large areas.
BIODIVERSITY -
Classification System
Linnaean Taxonomy was developed by Carolus Linnaeus and is used as the
scientific name of the organism. The greatest innovation of Linnaeus, and still the
most important aspect of this system, is the general use of binomial nomenclature,
the combination of a genus name and a single specific epithet to uniquely identify
each species of organism. For example, the human species is uniquely identified by
the binomial ‘Homo sapiens’. No other species of animal can have this binomial. The
naming of each organism uses the genera (genus) and species (species) to identify
each organism and how they are related to each other organism.
This classification system was much more reliable than previous systems, because it
used structural characteristics of the organism. Before Linnaean taxonomy, animals
were classified according to the way they moved, and their habitat.
All species are classified in a ranked hierarchy, originally starting with kingdoms
although domains have since been added as a rank above the kingdoms. Kingdoms
are divided into phyla (singular: phylum) — for animals; the term division, used for
plants and fungi, is equivalent to the rank of phylum. Phyla (or divisions) are
divided into classes, and they, in turn, into orders, families, genera (singular:
genus), and species (singular: species).
BIODIVERSITY -
Classification System
All organisms have been classified into 5 Kingdoms based on their structural
differences.
Animalia (animals)
Plantae (plants)
Fungi (yeasts, moulds and mushrooms)
Protista ( mostly single-celled organisms)
Monera (bacteria)
Each of these 5 Kingdoms are then further classified as …
Kingdom
phylum
class
order
family
genus
species
A species is a particular group of organisms that have the same structure and can reproduce with each other
ADAPTATION -
Structures and Functions
The special characteristics that enable plants and animals to be successful in a
particular environment are called adaptations.
Camouflage, as in a toad's ability to blend in with its surroundings, is a common
example of an adaptation.
The combination of bright orange and black
on a monarch butterfly is an adaptation
to warn potential predators that the butterfly
is poisonous and prevent it from being eaten.
Adaptations afford the organism a better chance to survive in its surroundings.
These special features have evolved over long periods of time, through the process
of natural selection.
ADAPTATION -
Structures and Functions
All animals live in habitats. Habitats provide food, water, and shelter which animals
need to survive, but there is more to survival than just the habitat.
Animals depend on their physical features to help them obtain food,
keep safe, build homes, withstand weather, and attract mates.
These physical features are called called physical adaptations.
Physical adaptations do not develop during an animal's life but over many
generations. The shape of a bird's beak, the number of fingers, color of the fur, the
thickness or thinness of the fur, the shape of the nose or ears are all examples of
physical adaptations which help different animals to survive.
An example of this are the finches Darwin discovered and studied on the Galapagos Islands
ADAPTATION -
Structures and Functions
NICHE
A niche describes the interrelationships of a species or population in an ecosystem. It
includes how a population responds to the abundance of its resources and enemies
(e. g., by growing when resources are abundant, and predators, parasites and
pathogens are scarce) and how it affects those same factors (e. g., by reducing the
abundance of resources through consumption and contributing to the population
growth of enemies by falling prey to them).
The abiotic or physical environment is also part of the niche because it influences how
populations affect, and are affected by, resources and enemies.
The description of a niche includes
descriptions of the organism's life history,
habitat, and place in the food chain. No two
species can occupy the same niche in the
same environment for a long time.
Sort of like, each piece of a puzzle can only
fit in one spot, in the overall picture.
NICHE -
Relationships of organisms
Each and every species depends on many other species within an environment in
order to survive and prosper.
Food Chain
Food Web
Food Pyramid
These represent different types of ongoing relationships between and among all
organisms, within a particular environment.
NICHE -
Distribution of Ecosystem Resources
Resource Partitioning,
Differentiation
or Separation
is the action which enables
competing species to share resources by
accessing these resources in different ways.
This natural selection process drives competing species into different patterns of
resource use or different niches. The process allows two species to partition certain
resources so that one species does not out-compete the other as dictated by the
competitive exclusion principle; thus, coexistence is obtained through the
differentiation of their realized ecological niches.
SURVIVAL -
Interdependence of Species
Interdependence is about or when a species depends on other species to perform
different roles. All living organisms are included.
Species interdependence is self-evident - the subsystems in a system constitute the
ecology and the balance it maintains, while the population-groups and the symbiotic
relations existing and evolving within the system demonstrate the 'interdependence'.
SURVIVAL -
Interdependent Relationships - Symbiosis
A different type of interdependence is an association, within a certain population,
between members of different species. There are different types of symbiotic
relationships:
Commensalism – in which one of the participating members benefits, but the other
does not, and there is no harm done to that organism.
(barnacles on a whale)
Mutualism – both organisms benefit from the relationship.
(lichen growing in the Arctic Tundra
- algae and fungi - benefit each other)
Parasitism – one organism benefits while the other organism (the victim) is harmed.
(the parasite usually doesn’t kill the host, because the host represents the parasite’s
food supply.
(tapeworm in a human host)
SURVIVAL -
Interdependence Of Species
Interspecies competition happens when two or more species need the same
resource. This type of relationship helps to limit the size of populations, of the
competing species.
Species Population
Limiting Factors
Survival
Factors
Resource partitioning is the action, which enables competing species to share
the resources by accessing these resources in different ways, involving less direct
competition.
SURVIVAL -
Natural Selection
Natural selection happens when factors in the environment determines, or ‘selects’
which individuals, within a species, will be able to survive. Many organism have
adaptations that defy our understanding of life. Scientists therefore hypothesize that
life may exist in the harsh environments on other planets. Living in an environment at
110oC or -35o C is rare, but possible because of adaptations organisms have to live in
these extremes.
Tube worms live on the ocean floor,
near black smokers, where volcanic vents
make the temperature extremely hot.
Antarctic springtail are arthropods that
live in extreme cold, by producing a kind
of antifreeze in its tissues.
Snow algae have cell membranes
adapted to cold temperature, making
their own food by photosynthesis. The
red color protects them from the intensity
of the sun on the snow.
If they are able to live long enough to reproduce, then those individuals with their
‘survival adaptations’ (characteristics) will have offspring with similar survival
characteristics.
SURVIVAL -
Environmental Change
Some of the most immediate effects of recent climate change are becoming apparent
through impacts on biodiversity.
The life cycles of many wild plants and animals are closely linked to the passing of
the seasons; climatic changes can lead to interdependent pairs of species (e.g. a wild
flower and its pollinating insect) losing synchronization, if, for example, one has a
cycle dependent on day length and the other on temperature or precipitation.
The Life Cycle of the Butterfly
In principle, this could lead to extinctions or changes in the distribution and
abundance of species
VARIATION
Variation within a population, of a single species, is called variability. Variability is
important if there is a sudden or drastic change in the environment, in which the
species lives.
When a species has a great deal of variation, then, some of the individuals within that
species will likely survive when there is change.
Examples of variability include:
Red fox (color of coat)
Antibiotic resistance
(bacteria)
Banded snail
(color of shell)
VARIATION -
Inherited or Non-Inherited
Variation is one of the most critical aspects of species survival. This variation may not
always be as easy to find as color usually is, because it may be a behavioral tendency
or a genetic (cellular code) modification that enables some individuals within a species
to survive, while others, of the same species, will perish.
Inherited (heritable) characteristics are those traits which are passed on to offspring
directly from their parents. These traits are passed on by way of the genetic material
that is combined from the parents during the process of sexual reproduction.
Heritable traits include, structural and
distinguishing characteristics, such as eye color,
hair type, skin color and earlobes.
VARIATION -
Inherited or Non-Inherited
Not all characteristics are inherited. Some depend entirely on the environment.
Non-inherited characteristics are acquired and not necessarily passed on from
generation to generation. Athleticism, artistic ability, leadership qualities are all
learned during the early years of life.
Some variations may be influenced by interactions with the environment. These
variations are also non-inherited. Examples include: change in the pigmentation of
skin color throughout the seasons due to the sun, height and weight can be
influenced by diet. Scars, injuries, clothing, hairstyle, make-up, and cosmetic surgery
may change a person’s characteristics, but they are not caused by genetics.
One way that scientists study the relationship between genetics and the environment
is to observe the similarities and differences between identical twins that have been
separated at birth and raised in different environments.
The interactions between a person’s genetics
and the environment are very complex and
are constantly being debated.
VARIATION -
Discrete or Continuous
Discrete variations are differences in characteristics that have a definite form. This
includes those individuals, within a species, that have either one characteristic, or the
single, other variation, of the characteristic. Examples of discrete variation include:
tongue rolling ability, blood groups, earlobe attachment, hairline, etc.
Continuous variations are differences in characteristics that have a range of possible
variations. The multitude of variations may include such traits as: height, shoe size,
hand span, skin color, hair color, etc.
REPRODUCTION -
Asexual Reproduction
Asexual reproduction involves only one parent. All of the offspring are identical to the
parent. There are different types of asexual reproduction:
Binary Fission - only single-celled organisms reproduce in this way. The cell splits
into two cells and each one is identical. (bacteria, amoeba, algae)
Budding - the parent organism produces a bud (a smaller version of itself), which
eventually detaches itself from the parent and becomes a self-sufficient individual identical to the parent. Coral also reproduces in this way, but do not detach
themselves (hydra, yeast, coral)
Spore Production - spores are similar to seeds, but are produced by the division of
cells on the parent, not by the union of two cells. One parent may produce many
spores, each of which will grow into a new individual, identical to its parent. (fungi,
green algae, moulds, ferns)
Vegetative Reproduction - is the reproduction of a plant not involving a seed,
including; cuttings, runners, suckers, tubers. (coleus plant, spider plants,
strawberries, aspen, potatoes)
REPRODUCTION -
Sexual Reproduction - Animals
Sexual reproduction in animals involves gametes (reproductive cells that have only
one role - to join with another gamete during reproduction).
The male gametes are called sperm cells, and the female gametes are called egg
cells (ova). During mating, the sperm cell and the egg cell unite to form a fertilized
combination of cells called a zygote. This zygote is the first of many cells of a new
individual. This zygote will begin to divide into two cells and this continues to be
repeated over and over resulting in the development of an embryo. This embryo
develops into a multi-cellular organism inside the female (in most mammals) or,
outside (in an egg shell) in other animals.
REPRODUCTION -
Sexual Reproduction - Plants
Sexual reproduction in plants involves gametes as well, male gametes and female
gametes joining, during fertilization, to produce a zygote and then an embryo. Most
plants produce both male and female gametes, while some produce one or the other
only.
Pollen contains the male gametes and is found on the
stamen. Ovules contain the female gametes and are
found in the pistil. Pollination occurs when pollen is
transferred from the anther of the stamen to the
stigma of the pistil.
Cross-pollination occurs when pollen from one plant is carried to the stigma of
another plant by wind, water or animals (bees or butterflies).
Cross-fertilization occurs when a grain of the pollen forms a long tube, which grows
down the style into the ovary. Gametes unite to produce a zygote, which then
develops into an embryo. This usually happens inside a seed, protecting the embryo
and providing food (cotyledon) for the embryo when growing conditions are right.
Plants which are produced, as a result of cross-fertilization, are not identical to either
plant.
REPRODUCTION -
Asexual and Sexual Reproduction
Organisms That Reproduce Sexually & Asexually
Most plants that produce seeds can also reproduce asexually (cuttings, runners).
Depending on the environmental conditions the amount of energy varies, enabling
the plant organism to control its population.
Sponges and Hydra are organisms
that can reproduce both sexually
and asexually.
Most plants that produce seeds can also reproduce asexually (cuttings, runners).
Depending on the environmental conditions the amount of
energy varies, enabling the plant organism to control its
population.
Mosses produce asexual spores in the early part of their life
cycle and then egg and sperm cells are produced in a later part
of the same cycle.
REPRODUCTION -
Asexual and Sexual Reproduction
Advantages and Disadvantages of Asexual and Sexual Reproduction
Variation usually helps a species survive when the environment changes.
Asexual reproduction does not require any specialized cells to produce a new plant.
It can therefore produce many plants very quickly. This is an advantage in places
where the environment doesn't change very much (bacteria). By building a large
population of organisms very quickly the species is able to thrive. The great
disadvantage is that when the environment changes, all of the organisms will die, if
they do not have the ability to adapt to the change.
Sexual reproduction has the advantage of providing lots of variation within a species,
helping it to survive when the environment changes. The main disadvantage is that
this process takes a lot of energy. This means that they can only produce small
populations.
REPRODUCTION -
Cell Division and Asexual Reproduction
Asexual reproduction involves only one parent. All of the offspring are genetically
identical to the parent. In single celled organisms, binary fission enables the parent
cell to split its contents equally between the two new cells. Prior to this division, the
parent cell duplicates its DNA and when the split takes place each new cell receives a
complete exact copy of the DNA, of the parent.
In multi-cellular organisms the process that
produces two new cells with the same
number of chromosomes is called Mitosis.
REPRODUCTION -
Cell Division in Plants and Animals
Sexual reproduction usually involves two individual organisms. The offspring that are
produced from this union have genetically different characteristics, half from one
parent and the other half from the other parent - making a unique offspring. During
sexual reproduction, the specialized sex cells (gametes) unite to form a zygote,
which develops into the new organism. When a male gamete and a female gamete
unite, meiosis takes place.
Meiosis is a type of cell division that
produces cells with only half the DNA of a
normal cell. This process involves two cell
divisions, not one.
REPRODUCTION -
Comparison of Meiosis & Mitosis
DNA
DNA is the blueprint that is passed on from the parents to the
offspring - is found in a molecule of the cell nuclei. This
molecule, desoxyribonucleic acid, (DNA) is the inherited material
responsible for variation. All living organisms contain DNA in
their cells.
DNA is the inherited material responsible for variation.
Characteristics are passed on from one generation to another
within a species through the genetic code of the parents. This
genetic code is called DNA.
Captive breeding programs enable scientists to control
populations of species at risk of extinction. Using modern
technology, geneticists and staff from zoos around the world can
analyze the genetic code of the species they are trying to save
and use it to introduce variation that will help the species survive
when the environment changes.
DNA – The Genetic Code
DNA was discovered prior to 1944. All DNA molecules contain exactly the same
chemicals, but the way the chemicals combine determines the characteristics of the
organism.
To solve the structural questions that DNA posed, four scientists, working in
groups of two, revealed that the same chemical building blocks could carry a wide
range of instructions needed for diversity.
3 scientists won the 1962 Nobel Prize in Medicine
for their work in modeling the structure of DNA.
James Watson
Francis Crick
Maurice Wilkins
The scientist who
died before she
could also be
recognized was …
Rosalind Franklin
DNA – The Genetic Code
Watson and Crick modeled the structure of DNA.
The DNA molecule is like a ladder twisted into a spiral.
The sides of the ladder are the same in all DNA molecules,
but the rungs are what make the variations.
Each rung pairs up two of the following chemicals:
guanine (G), cytosine (C), adenine (A) and thiamine (T)
The arrangement of these four chemicals creates the code that the cells are
able to interpret.
DNA - Chromosomes
DNA contains all the instructions, which create the organism's characteristics. The
multitude of characteristics for each organism means that there is a lot of DNA in any
one cell. This DNA is arranged in the cell in compact packages, called chromosomes.
Every human cell contains 46 chromosomes. In order to have a complete human
organism, all 46 of the chromosomes must be present. Not all organisms have the
same number of chromosomes (Dogs have 78, cats have 38). Every cell of a human
contains 23 pairs of chromosomes (dogs 39, cats 19). Not all of the chromosomes
from species to species are the same, which accounts for the different characteristics
between the species.
DNA - Genes
A single gene is an uninterrupted segment of DNA, which contains the coded
instructions for the organism.
Researchers found out that (by working on the fruit fly):
 Genes are located in the chromosomes
 Each chromosome has numerous gene locations
 Genes come in pairs
 Both genes in a pair carry DNA instructions for the same thing
 Specific characteristic genes occupy matching locations on the two
chromosomes
 DNA code may not be exactly the same in both locations
 Offspring inherit genes from both parents.
The genes exist in an array of possible forms that differ as to their exact DNA
sequence. These variations in forms are called alleles. The ultimate combination of
the chromosome pair is what makes the variation possible - combining the different
variations of different characteristics to create a unique variation.
GENETICS
To view a pdf of this image from the Human Genome Project this link is provided ...
http://www.genome.gov/11007524
GENETICS
Genetics is the study of heredity - traits inherited from parent to offspring.
Blending Theory
In ~1850, scientists thought that some fluid substance in the blood of animals or in
the sap of plants was the hereditary material. The combination of the parent's
characteristics in the offspring was thought to occur by a "blending" of this fluid.
If so, a white dog that mated with a brown dog should produce only tan puppies;
A tall person who had a child with a short person should produce all "medium-size"
children, etc...clearly not the case!
Even though people recognized problems with this theory, it was the top theory of
the day!
Keep in mind, though, that in the mid-1800s, very little was known about cell
structure, let alone the concepts of genes and DNA.
GENETICS
A new theory of how traits were passed on
from parents to offspring was put forth
by Gregor Mendel in 1850.
Mendel was an Austrian monk who was interested in plant breeding.
He performed careful experiments with the garden pea, Pisum sativum,
collected large amounts of data, and in doing so, was able to uncover the
basic principles of genetic inheritance that still hold true today!
Mendel's discoveries were not understood by other scientists for over 35
years! It was novel to only allow organisms with the most preferred traits to
reproduce. This method is not always successful, but over time ( trial and
error ), this practice of controlled breeding has enabled scientists to
determine which alleles were responsible for specific traits.
GENETICS - Purebred vs Hybrid
To produce purebred organisms, choose pure bred parents, those parents whose
ancestors have produced only the desired characteristic they want (true-breeding).
If a breeder chooses two different 'true-breeds' then a hybrid would be produced.
Cows
Bulls
Crossbreeding with purebred bulls for hybrid-vigor, The Bar-N Ranch & Cattle Co.
uses Horned Hereford bulls it produces from the registered herd, as well as purebred
bulls of other breeds to produce red baldy & brockle faced calves.
GENETICS - Purebred vs Hybrid
Purebred White Bass X Purebred Striped Bass ----> Hybrid Striped Bass
GENETICS - Dominant
vs Recessive Traits
Crossbreeding two different true-breeds will result in all of the offspring having the
same characteristic, that is, the dominant trait. Only the DNA instructions for the
dominant trait will be carried out. When crossbreeding hybrids, the average results
will produce 75% of the offspring with the dominant trait and 25% of the offspring
with the recessive trait, because there are only 4 possible combinations. One traits is
recessive and therefore the allele is recessive. A recessive trait only appears in the
offspring if two recessive alleles are inherited. [Punnitt Squares]
Environmental Factors can also determine how DNA is interpreted and developed.
Fetal alcohol syndrome can be a direct result of alcohol consumption during the
developing stages of the offspring. The 'normal' DNA is affected by the alcohol and
will not develop normally. Taking drugs can also affect the DNA during normal
development and defects in the organism can occur. (Thalidomide)
GENETICS - Patterns of Inheritance
Incomplete dominance occurs because the dominant-recessive pattern does not
always prevail. When the alleles are neither dominant, nor recessive, an intermediate
trait will occur (combining the two traits). In incomplete dominance, the effect of the
two alleles is blended.
Offspring Unlike Either Parent - More than one gene location and more than one
allele may be responsible for specific traits. As a result, the complex mixing of the
possible combinations for that particular trait may account for the variation of traits
an offspring has.
In codominance, both alleles are expressed
independently and are uniquely recognizable.
BIODIVERSITY -
Reduction
Stresses of urbanization and habitat intrusion by farming and industry have resulted
in a decline in genetic, species and ecosystem diversity. Extinction, population
decreases and degradation of ecosystems reduces biodiversity.
BIODIVERSITY -
Extinction and Extirpation
Extinction is the disappearance of every individual of a species from the entire
planet. It is a natural part of the Earth's history. 99% of species that have ever
existed on the Earth are now extinct (many by mass extinction - sudden
environmental change, like the Ice Age). Most extinction take place over long periods
of time, but the rate of extinctions is rising, and this is reducing the biological
diversity of our planet.
Extirpation is a local extinction,
or the disappearance of a species
from a particular area.
Burrowing Owl
BIODIVERSITY -
Natural Causes of Extinction & Extirpation
Natural selection is a slow process. Even if there is a lot of variation within a species,
sometimes the changes in the environment are so drastic that and so quick, that
none of the individuals within a species can survive.
Most extinctions, in the past, were due to:
catastrophic events (volcanic eruptions, earthquakes, floods, fire, comets)
lack of food (due to overpopulation)
disease (spread by insects)
Not all extinctions happened millions of years ago. Diseases and natural events occur
all the time and when they do, a species, within a particular area, can be extirpated
very quickly.
BIODIVERSITY -
Natural Causes of Extinction & Extirpation
Sometimes organisms have adaptations that suit them only to a very narrow set of
environmental conditions. This usually occurs in a relatively stable area, where the
environment does not change for a very long period of time. This is called
overspecialization and it is another cause of extinction. The giant panda is a
species that is overspecialized, because it relies on bamboo, making it vulnerable to
extinction, when the bamboo is scarce.
In the tropics, where the temperatures are relatively constant and food supply is
stable, organisms are also specialists. They efficiently survive in their environment,
because they have relatively narrow niches with adaptations directed toward
competing for one dependable food source, type of soil or level of light. This
specialization allows many different species to coexist in the same area, preventing
one species from becoming dominant. The result of this is high diversity with low
populations.
A specialist is well adapted to survive in one particular environment. This is
considered to be the ‘trap of specialization’, because, as it is able to survive very well
in one environment, it is not able to adapt to extreme change and may not survive
when this occurs. The cutting down of the rainforests have meant a loss of diversity,
because many organisms have been unable to adapt to this change.
BIODIVERSITY -
Human Causes of Extinction & Extirpation
Most extinctions and extirpations today are caused by human activity.
Habitat Destruction - as a result of Urbanization
Construction
Agricultural Development
Logging
Damming of rivers
Pollution
Pesticides, Herbicides and Fertilizers
The Grizzly Bear, as a bio-indicator species, helps us
to determine the human impact on an ecosystem.
This large carnivore’s ability to survive, or disappear,
is historically, a sign that human interference in an
ecosystem is occurring, or not.
BIODIVERSITY -
Human Causes of Extinction & Extirpation
Over-Hunting
This was the major cause of the decline
and eventual extirpation of the plains
Bison,
as well as,
the extinction of the passenger pigeon.
Over-hunting, over-fishing, and industrial-scale "mining" of natural resources have
placed many species in peril. Over-harvesting of fisheries has reduced the overall
diversity of marine life. Over-hunting and illegal trade in endangered species are a
prime threat to their survival.
Industrial-scale logging, for wood products and timber, destroys or fragments
millions of acres of forests each year, along with the habitat they provide to many
uniquely adapted species, such as the endangered red cockaded woodpecker.
Sometimes species are hunted to deliberately extirpate them. The black-tailed prairie
dogs were considered a pest in the 1930's and were hunted to reduce their numbers.
BIODIVERSITY -
Human Causes of Extinction & Extirpation
Introduction of Non-Native Species
When introduced species use the same resources, as the native species, the
competition will cause a decline in the numbers of native species, simply because
there is less to go around. The introduced species will have no natural predators to
limit its population and will, in time, take over from the native species.
Native Prairie Species
(Invasive) Non-native Species
BIODIVERSITY -
Effects of Extinction & Extirpation
Extinctions and extirpations reduce biodiversity.
When an organism disappears locally or globally,
many other species are affected.
• There are negative impacts on food webs,
symbioses, & species relationships.
• Loss of species that support many other
species: e.g. legumes, mycorrhizae, kelps.
• Loss of functional groups: e.g.
photosynthesizers, nitrogen fixers, pollinators.
• Reduction of ecosystem efficiency e.g. fewer
food webs, pollination or dispersal pathways.
• Reduction in community productivity
(amount of carbon fixed/unit area/time)
In short, the entire cycle of life is adversely affected.
ARTIFICIAL SELECTION
Long before Darwin, farmers and breeders were using the idea of selection to cause
major changes in the features of their plants and animals over the course of
decades. Farmers and breeders allowed only the plants and animals with desirable
characteristics to reproduce, causing the evolution of farm stock. This process is
called artificial selection because people (instead of nature) select which organisms
get to reproduce. The main difference between 'natural' selection and 'artificial'
selection is that, humans control the artificial selection process.
Artificial Selection ...
The process of selecting and breeding
individuals with desirable traits to produce
offspring with the desired traits. Only those
individuals, with the desired trait, will be
allowed to reproduce.
This selection process also applies to plants, which can be bred to possess desirable traits.
ARTIFICIAL SELECTION -
Biotechnology
The process of intervention to produce more desirable organisms has been going on
for some time. This process takes a long time to see results - usually many
generations. Farmers, dog and horse breeders,
along with scientists can now speed up the
artificial selection process by using 'low-tech'
or 'high-tech' technologies, such as;
cloning
(made from cells)
artificial insemination (artificially joining the male and female gametes)
in vitro fertilization (male and female gametes are selected and then allowed to
fertilize in a controlled setting)
genetic engineering (directly altering the DNA of an organism)
BIODIVERSITY -
Preserving Diversity - IN-SITU
Preserving global biological diversity is a challenge that is receiving much attention.
The 1995 Canadian Biodiversity Strategy was created to preserve biodiversity in
Canada. It will be done through the cooperation of many levels of government, along
with many groups, agencies and individuals, who are dedicated to preserving our
bio-diverse future.
IN-SITU conservation refers to conservation of components of biodiversity within
the natural habitat of the organisms being protected.
Protected Areas
National Parks, Provincial Parks, game preserves,
natural areas
Restoration Programs for Ecosystems and Species (Governments and Nature
Conservancy of Canada programs to purchase land for species habitat renewal,
individual landowners giving habitat back - in the form of a naturally protected area,
Ducks Unlimited CARE program, Swift Fox - restoration of a species - extirpated from
Canada and now recovering)
BIODIVERSITY -
Preserving Diversity - IN-SITU
Resource Use Policies (Laws - National Accord for the Protection of Species at
Risk - Species at Risk Act - Wildlife Act, 1998)
Controlling the Introduction and Spread of Exotic Species (Information and
teaching about the invasiveness of an exotic species is communicated to the public
on a regular basis. Penalties and fines, as well as loss of desirable areas for
recreational purposes, has improved the perception of the negative effect an exotic
species can have on a local ecosystem.)
Purple Loosestrife
(Everywhere)
Zebra Mussels (Great Lakes)
BIODIVERSITY -
Preserving Diversity - EX-SITU
EX-SITU conservation refers to conservation of components of biodiversity outside
of a natural habitat.
Conservation of Genetic Resources
The collection and storage of genetic resources, such as seeds (IPGRI)
Zoos (captive breeding programs)
Sperm and Egg Banks
Human Genome Project
Homo sapiens.
(HGP) was one of the great feats of
exploration in history - an inward voyage of
discovery rather than an outward
exploration of the planet or the cosmos; an
international research effort to sequence
and map all of the genes - together known
as the genome – of members of our species,
Completed in April 2003, the HGP gave us the ability to, for the first time,
to read nature's complete genetic blueprint for building a human being.