Descent with ModificationBy Natural Selection

Darwin’s influences Carolus Linnaeus (1707-1778)- Developed a classification system for all

known organisms.

Georges Cuvier (1769-1832)- Studied fossils near Paris. Noted differences between strata. Opposed to ideas of evolution

James Hutton (1726-1797) & Charles Lyell (1797-1875)- Both were geologists that suggested that the Earth’s geologic features could be explained by gradual mechanism’s that occurred in the past and were ongoing.

Hutton and Lyell’s ideas about geological processes were critical.

Provided physical evidence that the Earth was older than the common thinking of the day.

This was essential to Darwin’s ideas that change was gradual. Origin of new species under Darwin’s theory would take millions of years NOT a few thousand.

Another theory Jean-Baptiste de Lamarck ( 1744-1829)

Use and disuse Inheritance of acquired characteristics

Suggested that changes in organisms were purposeful. That they desired to be more complex. If you used a body part more, it became larger and stronger. You could then pass this trait to offspring. Example- Giraffe stretches his neck

Darwin was NOT influenced by Gregor Mendel (1822-1884)

While they were basically contemporaries, Darwin knew nothing of Mendel’s pea plant experiments.

He had no idea about the mechanism of inheritance.

Darwin’s Question

Could a new species arise from an ancestral form by gradual accumulation of adaptations?

Two observations1. Members of a population often vary in their inherited traits.

2. All species can produce more offspring than their environment can support and many of these fail to survive and reproduce.

Two inferences1. Individuals whose inherited traits give them a higher probability of

surviving and therefore reproduce in a given environment tend to leave more offspring.

2. This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations.

Four parts of Natural Selection Inherited variation

Overpopulation

Struggle to survive

Successful reproduction

Natural selectionA process in which individuals that have certain

inherited traits tend to survive and reproduce at a higher rate because of these traits.

An example of natural selectionThe peppered moth

The Industrial Revolution Factories

Soot covered trees

Lichens dying off

Which is more likely to survive?

What if the factories clean up their act?

Important things to know Environments change and act as selective mechanisms on populations

Variations are not directed by the environment but occur randomly

Some variations increase or decrease fitness of an organism to its environment.

Those organisms that are more “fit” will tend to survive, reproduce, and pass those desirable traits on

Humans can impact variation in other species

Now, which is likely to survive?

Descent with Modification by Natural Selection Explains: The unity of life

The diversity of life

The match between organisms and their environments

On my web site you will find the following link:

http://evolution.berkeley.edu/evolibrary/article/fireants_01

Please open it and read about the evolution of Fire Ants

Homework Below are some examples of natural selection in action. Pick 1 to research

and describe in 100 words or fewer. (Total word count) Lactose tolerance/ intolerance Nylon eating bacteria Methicillin- resistant Staphylococcus aureus (MRSA)

DUE THURSDAY 12/3