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.