biological diversity is usually the sign of a healthy ecosystem. the greater the diversity of...
TRANSCRIPT
BIODIVERSITY AND
CLASSIFICATION
BIODIVERSITY Biological diversity is usually the sign of
a healthy ecosystem. The greater the diversity of organisms
with in an ecosystem, the greater is the chance that some of those organisms will be able to survive change.
BIODIVERSITY There are two levels of biological
diversity:1. Genetic diversity, which describes the
variety of genes that code for different traits in a given species
2. Species diversity, which describes the number of different species.
CLASSIFICATION It is often difficult to determine if subtle
physical differences are variation within a species or variation between different species of closely related organisms.
Therefore, scientists need a classification system to help them study ecological diversity.
TAXONOMIC SYSTEMS Taxonomy – the science of classification
according to the inferred relation ships among organisms
TAXONOMIC SYSTEMS Biological classification systems have
two main purposes:1. Identifying organisms 2. Providing a basis for recognizing natural
groupings of living things.
TAXONOMIC SYSTEMS Carl Linnaeus (1707-
1778) Developed a system of
classification based on an organism’s physical and structural features, and operated on the idea that the more features organisms have in common, the closer their relationship.
TAXONOMIC SYSTEMS Carl Linnaeus (1707-1778) He was the first to use: Binomial nomenclature a method of
naming organisms by using two names – the genus name and the species name.
TAXONOMIC SYSTEMS Scientific name is often based on some
characteristic such as colour or habitat: Example
Castor canadensis Caster meaning beaver and canadensis meaning
from Canada
The first part of any scientific name is called the genus. The second part is called the species.
TAXONOMIC SYSTEMS The two-name system provides an
added advantage by indicating similarities in anatomy, embryology, and evolutionary ancestry.
TAXONOMIC SYSTEMS Present classification system there are
8 main levels or taxa.1. Domain2. Kingdom3. Phylum4. Class 5. Order6. Family7. Genus 8. species
Today most scientists believe that organisms have changed over time. The history of the evolution of organism is called phylogeny.
Relationships are often shown in a type of diagram called a phylogenetic tree.
Crash Course – Phylogeny Video
ASSIGNMENT Read pages 134-139 Do questions 6 and 7 on page 139 (Send
these to me)
Investigation pg 162 More Dichotomous Key Practice
EVIDENCE OF A CHANGING
EARTHCrash Course Video - Evolution
Evidence of evolution comes from many lines of investigation.
Some from direct observation and some more indirect.Direct Evidence:
FossilsRadiometric dating
Indirect Evidence
Comparative Anatomy
Homologous structures
Analogous structures
Embryology
Vestigial Organs
Physiology
Behaviour
Plant and animal breeding
Biochemistry and genetics
The geographic distribution of species
EVIDENCE FROM FOSSILS Paleontology – The study of fossils Fossilized remains, impressions, and
traces of organisms from past geological ages provide scientists with direct physical evidence of past life.
EVIDENCE FROM FOSSILS Patterns found in fossils:
1. Different species lived on Earth at various time in the past.
2. The complexity of living organisms generally increases from the most distant past to the present.
3. Living species and their most closely matching fossils are typically located in the same geographic region.
PBS Video – What do fossils tell us
FOSSILIZATION OCCURS IN MANY WAYS
· Organic components of the organism are replaced by minerals.
· Impressions left by organisms are preserved by the solidification of mud.
· Organisms can sometimes be caught in amber and preserved
FOSSILIZATION OCCURS IN MANY WAYS
Mammoths, bison and other extinct mammals have been found frozen in Arctic ice.
Acidic Bogs-conditions slow decomposition
PBS Video - Fossilization
DO YOU HAVE A DATE??
· Radiometric dating
· use the radioactive decay of certain elements to determine the age fossils
Example: Carbon-14 PBS Video – Radiometric Da
ting
EVIDENCE FROM BIOGEOGRAPHY Biogeography explores the variation and
distribution of live over the Earth’s surface, both today and the past.
Earth’s landmasses have undergone dramatic changes by the process of continental drift.
EVIDENCE FROM BIOGEOGRAPHY Evidence from biogeography suggest
that different species evolved independently in isolated parts of the world.
EVIDENCE OF EVOLUTION FROM BIOLOGY A comparison of the physical anatomy
and genetic makeup of organisms also provides evidence.
EVIDENCE FROM ANATOMY Comparative Anatomy
Homologous structures· Structures having similar genetic origin but
different uses in different species. Adaptive radiation: The pentadactyl limb has
evolved to suit many niches: digging, running, flying, swimming, etc. Ex: Flipper of dolphin and a forelimb of dog suggests a common ancestor
INDIRECT EVIDENCE FOR EVOLUTION
Analogous structures· Structures which are similar in
function and appearance but came from different ancestors.
· Examples: wing of an insect and a bird
Good indicators that these organisms did not evolve from a common ancestor
Illustrates convergent evolution development of similar forms from
unrelated species due to adaptation to similar environment
Crash Course Video – Comparative Anatomy
MORE INDIRECT EVIDENCE FOR EVOLUTION
Embryology· The study of organisms in their early stages of
development.· Closely related organisms go through similar
stages in their embryonic development· similarities in embryos suggests these organisms
have an evolutionary relationship.· Haeckel’s controversial pictures
· Exaggerated the similarities between embryos to support his scientific ideas
· The following diagrams are examples of these.· Mammals do show similar embryonic development
to each other though· PBS Video - Embryology
EMBRYOLOGY
EMBRYOLOGY
Vestigial OrgansA structure is considered vestigial
because it's not performing the function it was designed to perform, as compared to other creatures with the same part
Examples: coccyx and appendix in humans, vestigial leg bones in snakes
Vestigial OrgansThe appendix and coccyx (along
with other common human organs like tonsils, wisdom teeth, etc) do seem to have some functions in the bodyHelping the immune systemSupporting organs
However these are not the functions they seem to be designed to carry out.
Vestigial Organs In other vertebrates, the appendix
is much larger and more developed and aids in cellulose digestion (a plant carbohydrate that we can no longer break down)
So we consider it vestigial, not because it has no function at all, but because it is not doing what is used to (when our diet was more plant based)
EVIDENCE FROM BIOCHEMISTRY Evidence of evolution has also been
found by comparing biochemical characteristics of different species.
Biochemical Evidence Analysis of chemicals can be used to show
evolutionDNA and cytochrome enzyme C (respiration)
are similar in all organismsDNA analysis-used determine how closely
related organisms are· suggest a common ancestor
· Crash course video – Developmental Evolution
LAMARCK AND DARWIN
SOURCE OF VARIATION:
· Inherited: Determined by the DNA (genetic material) inherited from the parent
· i.e. hair, eye and skin color
· Acquired: Developed over life time.
· i.e. basketball skills, musical ability
HISTORY OF EVOLUTION
LAMARCK’ THEORY Lamarck believed that new species were
continually being created by spontaneous generationSpontaneous generation – the belief that
living things arose from non-living matter.
LAMARCK’ THEORY Theory of Use and Disuse: Use-
remains strong. Disuse-weakens and disappears. For example snakes legs.USE Each body part possesses a “will”
which allows it to change in order to better fit its environment. Eg. Short necked giraffe stretches its neck to
reach tree tops and it develops a longer neckDISUSE If a body part is not used it will
begin to disappear Eg. Nocturnal animals (ie. Bats) lose their vision
LEMARCK’ THEORY Theory of Acquired Traits: Traits
acquired in life time could be passed on to offspring. Inheritance of acquired characteristics
PROBLEMS WITH LAMARK’S THEORY “Use and Disuse” implies an organism
can sense its needs and physically change to meet those needs.
Acquired characteristics are not inherited
Never confirmed by experimentation.
PBS Video – Charles Darwin
DARWIN’S THEORY OF EVOLUTION
1. Overproduction
2. Variation.
3. Competition
4. Survival of the fittest
5. Passing on of successful traits (speciation)
Crash Course Video – Natural Selection
OVERPRODUCTION Overproduction means that the
number of offspring produced by a species is greater than the number that can survive.
VARIATION Differences among traits occur among
members of the same species. No two individuals are exactly alike Caused by:
MutationSexual Reproduction
STRUGGLE FOR EXISTENCE Competition Organisms of the same species, as
well as those of different species, must compete for limited resources such as food, water, and a place
Natural selection: Nature selects the organisms that survive
SURVIVAL OF THE FITTEST-NATURAL SELECTION
The most fit individuals survive Fittest means that the individuals are
best suited to the environment
ORIGIN OF NEW SPECIES (SPECIATION)
Successful individuals reproduce and pass on their traits
Over numerous generations, new species arise by the accumulation of inherited variation
When a type is produced that is significantly different from the original, it becomes a new species.
COMPARISON OF LAMARCK AND DARWIN
Darwin Organism vary
regardless of the environment
The environment then determines whether a variation is harmful (die) or helpful (survive)
Lamarck Individuals
change to suit their environment
Change is based on the need or “want” to change
Video – Darwin vs. Lamarck
Lamarck might be right? Read this article
SOURCES OF INHERITED VARIATION Variability in a species may arise from
two biological processes:1. Mutations 2. Sexual reproduction
MUTATIONS DNA, the hereditary material, is found in
the chromosomes of a cell. Genes are segments of DNA that code
for Specific traits. Mutation - a random change in the DNA
sequence in a chromosome.
MUTATIONS Mutations can by caused by:
1. Environmental factors Chemicals Radiation
2. Errors that arise when cells replicate
MUTATIONS Mutations are rare in individuals.
Neutral mutation – a mutation that has no effect on the organism
Harmful mutation – a mutation that reduces an organism’s fitness
Beneficial mutation – a mutation that enhances an organisms’ fitness.Beneficial mutations can be harmful to us,
when they improve bacteria’s fitnessPBS Video – Antibacterial Resistance
MUTATIONS Summary:
Mutations occur at random, with harmful mutations being more common than beneficial mutations.
Harmful mutations are selected against and therefore do not accumulate over generations.
Although beneficial mutations are rare, they are selected for and may accumulate over the generations.
MUTATIONS Beneficial Mutations in Humans
Sickle Cell Anemia is an example of a DNA mutation that can be beneficial in some environments.
PBS Video – Sickle Cell Anemia and Malaria A mutation that protects against HIV PBS Video – Double Immunity
SEXUAL REPRODUCTION AND VARIABILITY Asexual reproduction – production of
offspring from a single parent: offspring inherit the genes of that parent only. All offspring are identical to parents.
SEXUAL REPRODUCTION AND VARIABILITY Sexual reproduction – the production of
offspring by union of sex cells from two different parents. Offspring are never identical to the parents
or to other siblings.
Why are sexually-reproducing species so variable? There are three reasons.
1. Sexually-reproducing species have two copies of each gene. One from each parent.
2. The assortment of genes that an offspring inherits from either parent is determined randomly.
3. Sexually reproducing species choose different mates.
SPECIATION AND EVOLUTION
· Species· A group of similar organisms which share a
common gene pool· Organisms of the same species normally
interbreed in nature and are capable of producing fertile offspring
Population:
A group of individuals of the same species occupying a given area at a certain time
SPECIATION Speciation – the formation of new
species. Most new species are believed to arise
by a three-step process called allopatric speciation.
1. A physical barrier separates a single interbreeding population into two or more groups that are isolated from each other.
SPECIATION2. Natural selection works on the
separated groups independently, resulting in inherited differences in the two populations. (differences in selective pressures).
3. Physical and behavioral differences accumulate can no longer be sexually compatible.
New species evolve from a common ancestor in response to a new environment
Eg. From a common finch with a mid-sized beak the following finches evolved
Finch with a long beak for poking wood Finch with a short, hard beak for cracking seeds Finch with a long beak for drinking nectar
Crash Course Video – Speciation PBS video - Speciation and Natural Selecti
on
RATE OF EVOLUTION Theory of gradualism – the idea that
speciation takes place slowly. Theory of punctuated equilibrium-
the idea that species evolve rapidly followed by a period of little or no change. This theory has three main assertions:
1. Many species evolve very rapidly in evolutionary time
2. Speciation usually occurs in small isolated populations
3. After an initial burst of evolution, species are well adapted to their environment and do not need to change significantly for a long period.
METHODS OF SPECIATION: Transformation of one species into
another Branching evolution: one or more
species branch off a parent species which continues to exist.
DIVERGENT EVOLUTION – EVOLUTION INTO MANY DIFFERENT SPECIES.
ADAPTATION AND CHANGE Convergent
Evolution the development of
similar forms from unrelated species due to adaptation to similar environments.
Ex: the torpedo shape of dolphins and sharks. Over time, the two began to look more and more alike.