Transcript Lesson 1. Biodiversity and The Nature of - Blyth-Biology11

SBI3U: Biology, University Preparation
1.
2.
3.
4.
Diversity of Living Things
Genetic Processes
Evolution
Animals: Structure and Function
(Digestive, respiratory, circulatory systems)
5. Plants: Anatomy, Growth and Function
What can you expect in this course?
• BIG IDEAS stated at the start of each unit
• Clear lesson goals at the start of EACH lesson
• Quizzes at the end of each chapter (2-3 chapters per
unit)
• A lab, an assignment, and a unit test for each unit
• A Wikispaces course homepage to access ppt
presentations, worksheets, links to games and sites
What can you expect in this
course?
• Due to the condensed nature of this course (we
only have 30 classes!) material will move
quickly.
• In one class we will cover roughly 20 pagesworth of the text book.
• It is vital that you review notes between classes
and complete assigned homework to succeed in
this course
The Breakdown
•
•
•
•
Knowledge/Understanding
Thinking/Inquiry
Communication
Application
•
•
•
•
Tests
Assignments/projects
Labs
Quizzes
• Final Exam
30%
25%
20%
25%
30%
15%
15%
10%
70%
30%
100%
UNIT 1. Diversity of Living Things
• BIG IDEAS:
– All living things can be classified
according to their anatomical and
physiological characteristics
– Human activities affect the diversity of
living things in ecosystems
Biodiversity
and
The Nature of Classification
Lesson 1.
Learning Goals
• Describe the nature of biological diversity and
the biological species concept
• Outline some of the primary human-caused
threats to Earth’s biodiversity
• Explain the principals of taxonomy and the
concepts of taxonomic rank
• Construct and apply dichotomous keys for the
purpose of identifying species
Biodiversity
• Biodiversity: The number and variety of
species and ecosystems on Earth
• By 2010, over 1.7 million kinds of living
things had been identified
• Earth may be home to as many as 15
million different kinds of living things! (So
why haven’t we found them yet?)
Of all the species that have ever lived
on Earth, how many are living today?
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•
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less than 1%
1%
10%
20%
50%
0.1%, so in other words 99.9% of all species that have
ever lived are extinct!
Greatest Mysteries: How Many
Species Exist on Earth?
What is a Species?
• A species is a group whose members are able
to freely breed among themselves under natural
conditions
• Some plants, some fungi and micro-organisms
only reproduce asexually, so traditional species
definition does not apply
– Use set of physical characteristics (morphology) to
define them
Individual Variability
• A species is composed of individuals with
different traits
• Individuals may show subtle differences…But…
• Still belong to the same species and are
members of the same breeding population
• Organisms in the
same species can
interbreed to
produce viable
offspring.
• These cannot....
• Species change over time and space.
They can evolve over many generations,
and they can change across continents
– Five Subspecies of rat snake
Diversity in Ecosystems
• Ecosystems are made up of many different
species and their physical environments
• All species depend on other species for their
survival:
– Organisms that cannot make their own food
(heterotrophs) feed on other living or dead
organsims
– Even organisms that make their own food
(autotrophs) are dependent on other organisms
Diversity of Interactions
• Interdependence between species goes
far beyond simple food chains and
biogeochemical (?) cylces:
• Plant communities with high species
diversity are better able to withstand
disease, climate extremes and pests
Diversity of Habitats
• The range of physical sizes, shapes and distribution of
the individuals, as well as habitats in an ecosystem
are together referred to as structural diversity
• Structural diversity is critical for biodiversity because it
creates microhabitats
Biodiversity at Risk
• The loss of biodiversity:
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Threatens our food supply
Eliminates sources of medicines
Economic impact on tourism and forestry
Potential to disrupt biogeochemical cycles by ecosystems
(carbon, nitrogen…)
• Species extinction is a natural process. However….
• Human actions are resulting in a rapid loss of natural
habitats from agriculture, forestry, urban expansion,
invasive species and climate change
• Biologist E.O Wilson estimates that the current extinction
rate may be 10 000 times greater than it would be without
humans
The Nature of Classification
• For hundreds of years people have been trying
to classify the species on our planet Earth
• There are potentially hundreds of thousands
new species still waiting to be discovered
• With the discovery of new species
classification of organisms is constantly being
modified
• The goal is to track evolution and determine
which organisms share common ancestors
• A simple system of naming organisms allows
anyone in the world to discuss the same creature
regardless of its common name
• For example....
• But, Carolus Linnaeus calls him....
Melanoplus femurrubrum
http://upload.wikimedia.org/wikipedia/commons/6/68/Carl_von_Linné.jpg
• Linnaeus classified organisms according to their
structural similarities: this is called TAXONOMY
• Each group to which Linnaeus assigned
organisms is called a TAXA (singular is TAXON)
• Modern taxonomy groups based on their
evolutionary relatedness: this is called
PHYLOGENY
• Organisms share common ancestry if they show
similar stages of embryological development
and anatomical structures.
• The 18th century Swedish
naturalist Carolus Linnaeus
simplified the system of naming
and classifying organisms
• The system, known as
binomial nomenclature is
still in use today!
• What are the two parts?!
Let’s find out......
http://upload.wikimedia.org/wikipedia/commons/6/68/Carl_von_Linné.jpg
Linnean Classification
Name: Orcinus orca
• The taxon “species” is the smallest group
and it contains only a single type of
organism.
• The organisms in a species are most like
one another
• The individuals of a species have the same
body or physiological morphology.
How Many Kingdoms?
• Archaebacteria
• Eubacteria
• Protista
• Fungi
• Plantae
• Animalia
Dichotomous Keys
• Dichotomous classification keys are used to
help place organisms into the appropriate
classification group
• Classification keys include two choices for
each characteristic
Dichotomous Key Activity
Dichotomous Keys
Dichotomous Keys
• Dichotomous classification keys are used to help place
organisms into the appropriate classification group.
• It is a tool that allows the user to determine the identity of
items in the natural world, such as trees, wildflowers,
mammals, reptiles, rocks and fish.
• These keys consist of a series of choices that lead the
user to the correct name of a given item.
• “Dichotomous” means “cut into 2 parts”. Therefore,
these keys always give two choices in each step.
When Constructing Dichotomous Keys:
• Use constant characteristics rather than variable ones.
• Use measurements rather than terms like “large” or “small”.
• Use characteristics that are generally available to the user of the
key rather than seasonal characteristics or those seen only in the
field.
• Make the choice a positive one – something “is” instead of “is
not”.
• If possible, start both choices of a pair with the same word.
• If possible, start different pairs of choices with different words.
• There should be one less step than there are total
organisms to classify.
• The first step in the key should divide the organisms in
roughly half.
• Both choices of a pair should be about the same
attribute.
When Using Dichotomous Keys
• Always read both choices, even if the first seems to be the
logical one at first.
• Be sure you understand the meaning of the terms involved.
Do not guess.
• If the choice is not clear, for whatever reason, try both
divisions. If you end up with two possible answers, read
descriptions of the two choices to help you decide.
• Having arrived at an answer in a key, do not accept this as
absolutely reliable. Check a description of the organism to
see if it agrees with the unknown specimen.
Dichotomous Keys
Example of the Graphical form
Example of the Written form