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Week 5
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.
• There are two levels of biological diversity:
1. _______________, which describes the variety of genes that
code for different traits in a given species
2. _______________, which describes the number of different
species.
• 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
• ___________________ – the science of classification according to the
inferred relationships among organisms
• Biological classification systems have two main purposes:
1. Identifying organisms
2. Providing a basis for recognizing natural groupings of living
things.
• 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.
• He was the first to use :
• _______________________ a method of naming organisms by using two
names – the genus name and the species name.
• Scientific name is often based on some characteristic such as colour or
habitat:
• Example
• Castor canadensis
1. Caster meaning beaver and canadensis meaning from Canada
• The first part of any scientific name is called the __________. The second
part is called the _____________.
• The two-name system provides an added advantage by indicating similarities
in ____________, ____________, and _______________ ancestry.
• Present classification system there are seven main levels or taxa.
1. _________________
2. _________________
3. _________________
4. _________________
5. _________________
6. _________________
7. _________________
• Today most scientists believe that organisms have changed over time. The
history of the evolution of organism is called ________________.
• Relationships are often shown in a type of diagram called a phylogenetic
tree.
Week 5 Practice
 Read pages 134-139
 Do questions 6 and 7 on page 139 (Send these to me)
 Investigation pg 162
Summative Assignment (instructions on PowerSchool)
Week 6
Evidence of a Changing Earth
• Evidence of evolution comes from many lines of investigation.
• Some from direct observation and some more indirect.
• Evidence gathered from:
____________________
 Fossils
 Radiometric dating
____________________
 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 – ____________________________________.
• Fossilized remains, impressions, and traces of organisms from past
geological ages provide scientists with direct physical evidence of past life.
• 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.
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
 Mammoths, bison and other extinct mammals have been found frozen
in Arctic ice.
 Acidic Bogs-conditions retard decomposition
Radiometric dating
 use the radioactive decay of certain elements to determine the age
fossils
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 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.
• Comparative Anatomy
• Homologous structures
• ___________________________________________________
________________________________________.
• 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
• Analogous structures
 ________________________________________________________
_____________________________________________.
 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
 Embryology
• ___________________________________________________
________________________________________.
• Closely related organisms go through similar stages in their
embryonic development
• similarities in embryos suggests these organisms have an
evolutionary relationship
 Vestigial Organs
• _____________________________________________
• Examples: coccyx and appendix in humans, vestigial leg bones
in snakes
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 evolution
• DNA and cytochrome enzyme C (respiration) are similar in all
organisms
• DNA analysis-used determine how closely related organisms are
• suggest a common ancestor
Lamarck and Darwin
Source of Variation:
 Inherited: _______________________________________________.
o i.e. hair, eye and skin color
 Acquired: _______________________________________________.
 i.e. basketball skills, musical ability
Lamarck’s Theory
• Lamarck believed that new species were continually being created by
spontaneous generation
– Spontaneous generation –the belief that living things arose from nonliving matter.
• _________________________ : 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 neck
– DISUSE
If a body part is not used it will begin to disappear
• Eg. Nocturnal animals (ie. Bats) lose their vision
• ________________________: Traits acquired in life time could be passed
on to offspring. Inheritance of acquired characteristics
Problems with Lamarck’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.
Darwin’s Theory of Evolution
1. __________________________
2. __________________________
3. __________________________
4. __________________________
5. __________________________
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:
– Mutation
– Sexual Reproduction
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
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 Darwin and Lamarck
Darwin
Lamarck
Sources of Inherited Variation
• Variability in a species may arise from two biological processes:
1. ____________________
2. ____________________
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 can by caused by:
1. Environmental factors
• _____________________
• _____________________
2. Errors that arise when cells replicate
• Mutations are rare in individuals.
• _________________ – a mutation that has no effect on the organism
• _________________– a mutation that reduces an organism’s fitness
• _________________– a mutation that enhances an organisms’ fitness.
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.
Sexual reproduction and Variability
• Asexual reproduction – production of offspring from a single parent:
offspring inherit the genes of that parent only.
– __________________________________________________.
• Sexual reproduction – the production of offspring by union of sex cells from
two different parents.
–
__________________________________________________.
• Sexually-reproducing species are variable. 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
________________:
 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
 _______________:
– A group of individuals of the same species occupying a given area at
a certain time
Speciation
• Speciation –_____________________________________________.
• Most new species are believed to arise by a three-step process called
_____________________.
1. A physical barrier separates a single interbreeding population into two or
more groups that are isolated from each other.
2. Natural selection works on the separated groups independently, resulting in
inherited differences in the two populations. (defenses 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
1. Finch with a long beak for poking wood
2. Finch with a short, hard beak for cracking seeds
3. Finch with a long beak for drinking nectar
Rate of Evolution
• Theory of gradualism – ____________________________________.
• Theory of punctuated equilibrium-____________________________
________________________________________________________.
• 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.
Transformation of one species into another
• ____________________: one or more species branch off a parent species
which continues to exist.
• Divergent evolution – ______________________________________.
Homologous structures! – Related but different forms
• Convergent Evolution
– ___________________________________________________
__________________________________________________.
– Ex: the torpedo shape of dolphins and sharks. Over time, the two
began to look more and more alike.
Analogous structures! – not related but similar forms
Week 6 Practice
 Do question 1 (pg 152), #3 (pg 156) (Send these to me)
 Do #1-11 pg 168 (send me #3,6,7,8)
 Do #3,12,13,36 pg 170 (send me 3,13,36)