Unit 1 – Evolutionary Theory and Biodiversity

UNIT 1 – EVOLUTIONARY THEORY AND BIODIVERSITYClass 2 -

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Evolution of the Telephone2

Biodiversity - Introduction Estimates of the number of species that inhabit our

planet run as high as 10 million! That means 10 million different kinds of organisms. That number certainly suggests a lot of variety. That is what diversity means--variety. When we say "biodiversity," we refer to the variety of life.

It is interesting to try to imagine how so many forms of life came about. If we also think about extinct forms, it becomes truly mind boggling.

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Origin of Life How did life begin on Earth?

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Examples of Evolution

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Evolution - Definition Biological evolution, simply put, is descent

with modification. small-scale evolution (changes in gene

frequency in a population from one generation to the next)

large-scale evolution (the descent of different species from a common ancestor over many generations).

Evolution helps us to understand the history of life.

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Evolution – The Explanation Biological evolution is not simply a matter of

change over time. Lots of things change over time: trees lose

their leaves, mountain ranges rise and erode, but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.

The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother.

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The History of Evolutionary Theory James Hutton (1726-1797) and Charles

Lyell (1797-1875) studied the forces of wind, water, earthquakes and volcanoes. They concluded the earth is very old and has changed slowly over time due to natural processes.

Erasmus Darwin (1731-1802) suggested that competition between individuals could lead to changes in species. (He also was Charles Darwin’s grandfather.)

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The Theory Continued … Jean Baptiste Lamarck (1744-1829)

proposed a mechanism by which organisms change over time. He hypothesized that living things evolve through the inheritance of acquired characteristics.

Thomas Malthus (1766-1834) observed that human populations cannot keep growing indefinitely. If the birth rate continued to exceed the death rate, eventually humans would run out of living space and food. Famine, disease and war prevented endless population growth.

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continued Charles Darwin (1809-1882) formulated a

theory of evolution by natural selection based on observations made during his voyage on the Beagle, and of selective breeding of farm animals, plants and pets. Darwin drafted manuscripts outlining his theory in the 1840’s but hesitated to release them to the public. His most famous work On the Origin of Species by Means of Natural Selection was published in 1859.

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More … Alfred Russell Wallace (1823-1913)

proposed a theory of evolution by natural selection similar to that of Darwin. He wrote a paper and sent it to Darwin to review. This spurred Darwin on to finally agree to the release of his theory. In 1858 Charles Lyell presented Darwin’s 1844 essay and Wallace’s paper to the public.

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Charles Darwin12

Charles Darwin Basis of modern evolutionary theory HMS Beagle

1831 (age 22) – Darwin took a job as a naturalist on this ship which sailed around the world on a five year scientific journey.

Studied and collected biological and fossil specimens at every port along the route.

This made Darwin curious about possible relationships among species.

These studies provided the foundation for his theory of evolution by natural selection.

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Darwin In the Galapagos Islands

Small islands near the equator (1000 km off the west coast of South America).

Observations and specimens were very important

Many species of animals are unique to the islands, but similar to species elsewhere.

Led Darwin to consider the possibility that species can change over time.

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Darwin Darwin continued to work to refine his

explanation for how species change over time for the next two decades.

Modified idea by Thomas Malthus that the human population grows faster than Earth’s food supply.

This led Darwin to the idea of artificial selection ( the process of breeding organisms with specific traits in order to produce offspring with identical traits)

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Darwin’s Theory of Natural Selection

Overproduction: more offspring are produced by an organism than can possibly survive

Competition: high birth rates cause a shortage of life’s necessities leading to competition between organisms

Variation: each individual differs from all other members of its species; some differ more than others

Adaptation: allows organisms to become better suited to their environment

Natural selection: the most fit (best adapted) organisms survive and reproduce

Speciation: formation of new species from ancestral species by means of natural selection

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Minilab 15.1 Camouflage Provides an Adaptive

Advantage – Camouflage is a structural adaptation that

allows organisms to blend with their surroundings. In this activity, you’ll discover how natural selection can result in camouflage adaptations in organisms.

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Structural Adaptations Arise over time (many generations) Structural adaptations are special body parts

of an organism that help it to survive in its natural habitat (e.g., skin colour, shape, body covering). Mimicry – a structural adaptation that enables

one species to resemble another species. (p.398)

Camouflage – an adaptation that enables species to blend with their surroundings. (p.398)

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Behavioural Adaptations Behavioural adaptations are special

ways a particular organism behaves to survive in its natural habitat. Bird calls; migration

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Physiological Adaptations Physiological adaptations are systems

present in an organism that allow it to perform certain biochemical reactions (e.g., making venom, secreting slime, being able to keep a constant body temperature). Penicillin – 50 years ago it was

considered a “wonder drug” because it killed many types of disease-causing bacteria, and saved many lives. Today, penicillin no longer affects as many species of bacteria because some species have evolved physiological adaptations to prevent being killed by penicillin.

Insects/weeds resistant to chemicals that used to kill them.

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Other Evidence for Evolution Fossils

Provide a record of early life and evolutionary history. Ancestors of whales were probably land-

dwelling, dog-like creatures. Missing pieces – do not have fossils for

every creature

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continued Anatomy

Homologous structures – structural features with a common evolutionary origin. Can be similar in arrangement, in function, or in both

Doesn’t necessarily mean that two species are closely related (butterfly/bird)

Analogous structures – body parts of organisms that do not have common evolutionary origin, but are similar in function

Vestigial structures – structures that exist in present-day organisms that no longer serve their original purpose. Eyes on blind mole-rats

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Embryology The shared features in the young

embryos of different organisms (fish, reptile, bird, mammal) suggest evolution from a distant, common ancestor.

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Biochemistry Nearly all organisms share DNA and

different enzymes in their biological makeup.

P 403 #1-4

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Poster The poster should include:

The name of the species A description of the adaptation The type of adaptation present (behavioural,

physiological, structural) An explanation of how the adaptation allows an

organism to be better suited to its environment.

A picture, drawing or diagram of the organism Due Thursday April 19

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UNIT 1 – EVOLUTIONARY THEORY AND BIODIVERSITYSupplementary Activities

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Who was Darwin?

Once notes are finished, watch (50 minutes) http://video.google.ca/videoplay?docid=-4471435322910215458&ei=z1WeS9z7EZLplQelq_iwDQ&q=darwin&hl=en#

PBS also has a great video “EVOLUTION” available on youtube

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