Introduction to Evolution – Chapter 10

Freshman Honors Biology

Evolutionary Theory Timeline

1735- Carolus Linnaeus, classification 1785- James Hutton, geology 1798-Thomas Malthus, economist 1809- Jean Baptiste Lamarck, naturalist 1831 to 1835- Voyage of the H.M.S.

Beagle 1833- Charles Lyell, geologist 1858- Alfred Wallace, naturalist 1859- Charles Darwin, published

naturalist

James Hutton

Geologist Proposed that the Earth was millions

(not thousands) of years old Based on the processes of rock

upheaval (uplift) and weathering

Thomas Malthus

Economist Proposed that humans would run out of

resources like food and space if the human population numbers continue to grow

If food and space are scarce, there will be competition for them

Jean Baptiste Lamarck

French naturalist Proposed one of the first theories about

how species change over a period of time (evolution)

In Lamarck’s theory, individuals evolved

Lamarck’s Theory

Three Principles› Tendency Towards Perfection

Innate tendency towards complexity and perfection

› Use and Disuse Organism develops new adaptation by using the

structure more Organism loses an adaption by not using the

structure› Inheritance of Acquired Traits

Traits acquired by an organism can be passed on to the next generation

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Charles Lyell

Geologist Published “Principles of Geology” Also proposed that the Earth is very old Proposed the forces at work in geology

today are the same forces that have shaped the structures throughout time on Earth

This had to take a long time

Alfred Wallace

Naturalist Independently proposes theory of

evolution Writes Darwin about theory prompting

him to publish his theory formed many years before

Charles Darwin

Born the same day as Abraham Lincoln

Studied theology in college Became the naturalist

aboard the H.M.S. Beagle Proposed theory of evolution

based off of observation from that trip

Published theory in On the Origin of Species in 1859

Voyage of the H.M.S Beagle

Sailed from England Traveled to

› South America› Africa› Australia› New Zealand› Galapagos

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Voyage of the Beagle (cont)

Darwin studied› Difference within and between species› Living specimens› Fossils › Geology

Galapagos Islands

Group of islands off the coast of South America

Each island has a unique climate Darwin observed

› Marine iguanas› Tortoises› Finches

Darwin’s Theory of Evolution

1. Variation› Individuals naturally vary from each other› Variations that are genetically based can

be passed on from one generation to the next (although Darwin did not know how)

Darwin’s Theory of Evolution (Continued)

2. Struggle for Existence (overproduction)› Most populations grow past their resources› Organisms within a population must

compete for their share Food Space Mates Other necessities

Darwin’s Theory of Evolution (continued)

3. Survival of the Fittest (Natural Selection)

› Organisms have adaptations (inherited variations) that make them a good match to their environment (fitness)

› Individuals with better fitness survive longer and reproduce more therefore passing on their genes

› Future generation have more individuals with the well-fitted adaptation

› It is about reproduction not survival!!!

Adaptations for Fitness

Survival› Camouflage › Bright coloration› Strength› Heightened senses › Behavior

Reproduction› Strength› Costly structures› Behavior

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Darwin’s Theory of Evolution (Continued)

Artificial Selection› Most fit adaptations are based on human

choices› Individuals are bred to pass on desired

traits

Darwin’s Theory of Evolution (continued)

4. Descent with Modification› Individuals have

common descent› Evolution over a long

period of time diversifies species

› All species descend from common ancestor

› Cladograms- diagram showing evolutionary relationships

Evidence for Evolution

1. Fossil Record› Darwin knew fossils represented dead

organisms› Also knew that newer organisms were

closer to the top› Record showed evidence of change over

time

Evidence for Evolution (continued)

2. Geographical Distribution of Living Species› Beaks of Galapagos Finches › Neck Length and Shell Shape for Tortoises› Various Variations for Marine Iguanas› Pattern of Organisms in Similar

Environment

Evidence for Evolution (continued)

3. Anatomy/Body Structures› Homologous

Structures that develop from the same embryonic tissues

Mature forms often have similarities but may look different and have different functions

› Vestigial Structures that no longer have a function for

an organism but are still present

Homologous Structures

Vestigial Structures

Evidence for Evolution (continued)

4. Embryology› Many embryos

look similar to each other during development and develop in similar ways

Evidence for Evolution (continued)

5. Molecular and Genetic Comparisons› Scientists compare DNA sequences and

proteins between species to support fossil and anatomy comparisons

Alligator Book p. 317