 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.
2.
Genetic diversity, which describes the variety of
genes that code for different traits in a given
species
Species diversity, 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.
 Taxonomy
– the science of classification
according to the inferred relation ships
among organisms

Biological classification systems have two
main purposes:
1.
2.
Identifying organisms
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.
 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.
 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.
 The
two-name system provides an added
advantage by indicating similarities in
anatomy, embryology, and evolutionary
ancestry.

Present classification system there are 8
main levels or taxa.
1.
2.
3.
4.
5.
6.
7.
8.
Domain
Kingdom
Phylum
Class
Order
Family
Genus
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
 Read
pages 134-139
 Do questions 6 and 7 on page 139
 Investigation pg 162
 More Dichotomous Key Practice
(Send these to me)
Crash Course Video - Evolution

Evidence of evolution comes from many lines of investigation.

Some from direct observation and some more indirect.
 Direct Evidence:


Fossils
Radiometric 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
 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.

Patterns found in fossils:
1.
2.
3.
Different species lived on Earth at various
time in the past.
The complexity of living organisms generally
increases from the most distant past to the
present.
Living species and their most closely
matching fossils are typically located in the
same geographic region.
PBS Video – What do fossils tell us
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
slow decomposition
PBS Video - Fossilization

Radiometric dating

use the radioactive decay
of certain elements to
determine the age fossils

Example: Carbon-14

PBS Video – Radiometric Dating


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.
A
comparison of the physical anatomy and
genetic makeup of organisms also provides
evidence.
 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
 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

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
 Vestigial
Organs
A 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
Organs
The appendix and coccyx (along with
other common human organs like
tonsils, wisdom teeth, etc) do seem to
have some functions in the body
 Helping the immune system
 Supporting 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
of evolution has also been found by
comparing biochemical characteristics of
different species.
 Biochemical



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


Evidence
suggest a common ancestor
Crash course video – Developmental Evolution

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
 Lamarck
believed that new species were
continually being created by spontaneous
generation

Spontaneous generation – the belief that living
things arose from non-living matter.
 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 neck
DISUSE
If a body part is not used it will begin
to disappear

Eg. Nocturnal animals (ie. Bats) lose their vision
 Theory
of Acquired Traits: Traits acquired in
life time could be passed on to offspring.
Inheritance of acquired characteristics
 “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
1. Overproduction
2. Variation.
3. Competition
4. Survival of the
fittest
5. Passing on of successful
traits (speciation)
Crash Course Video – Natural Selection
 Overproduction
means that the number of
offspring produced by a species is greater
than the number that can survive.
 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
 The
most fit individuals survive
 Fittest means that the individuals are best
suited to the environment
 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.
Darwin
Lamarck
 Organism vary
 Individuals change
regardless of the
to suit their
environment
environment
 The environment then  Change is based on
determines whether a
the need or “want”
variation is harmful
to change
(die) or helpful
(survive)
Video – Darwin vs. Lamarck
Lamarck might be right? Read this article

Variability in a species may arise from two
biological processes:
1.
2.
Mutations
Sexual reproduction
 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.
2.
Environmental factors
 Chemicals
 Radiation
Errors that arise when cells replicate
 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 fitness
PBS Video – Antibacterial Resistance
 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.





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
 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 – 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.
2.
3.
Sexually-reproducing species have two copies of
each gene. One from each parent.
The assortment of genes that an offspring inherits
from either parent is determined randomly.
Sexually reproducing species choose different
mates.

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


1.
Speciation – the formation of new species.
Most new species are believed to arise by a
three-step process called allopatric
speciation.
A physical barrier separates a single
interbreeding population into two or more
groups that are isolated from each other.
2.
3.
Natural selection works on the separated
groups independently, resulting in
inherited differences in the two
populations. (differences in selective
pressures).
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 Selection


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.
2.
3.
Many species evolve very rapidly in
evolutionary time
Speciation usually occurs in small isolated
populations
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
 Branching evolution: one or more species
branch off a parent species which continues
to exist.
 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.