Unit 2: Evolution Learning Goal 1: Examine the history of the development of the theory of evolution.

Unit 2: Evolution

Learning Goal 1: Examine the history of the development of the theory of evolution.

Scientific Theory

A well supported testable explanation of phenomena that have occurred in the natural world.

Charles Darwin (1809-1882)

First attended the University of Edinburgh to become a surgeon.

Transferred to Cambridge to study theology and become an Anglican priest.

Graduated at the age of 22 (1831) and joined the HMS Beagle.

– Father did not want him to join the ship because it might lead him away from a future in the clergy.

– Started as the captains companion and later became the ship’s naturalist.

I have called this principle, by whicheach slight variation, if useful, is preserved,

by the term Natural Selection.

  —Charles Darwin from "The Origin of Species"Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

http://evolution.berkeley.edu/evolibrary/home.php

http://evolution.berkeley.edu/evolibrary/home.php

www.darwinday.org/englishL/life/beagle.htUsed by permission of Darwin Day Celebration (at DarwinDay.org), 2006

www.darwinday.org/englishL/life/beagle.html

http://evolution.berkeley.edu/evolibrary/home.php

Five-Year Voyage

HMS Beagle

Darwin’s Observations

Patterns of Diversity– Darwin observed similar animals that were

diverse in their characteristics.

Darwin’s Observations

Fossils – a large part of the puzzle.– A fossil is preserved remains

of ancient organisms.

Many animals found in

fossils were very similar to

modern day organisms.

Galapagos Islands

Darwin observed that the characteristics of many plants and animals varied noticeably among the different islands.

Galapagos Islands

Each island had a very different climate.– The smallest, lowest islands were hot, dry, and

nearly barren. Sparse vegetation

– Higher islands had greater rainfall. Different assortment of plants and animals.

Island Tortoises

Darwin found that the shape of the shell of the tortoise varied from island to island. – You could use the shape of the shell to determine

where the tortoise had come form.

Galapagos Iguanas

Galapagos Iguanas

The iguanas seemed to adapt to their environments.

Those that lived near trees had feet and claws adapted for climbing in soft tissue.

Those that lived on rocky cliffs had feet and claws adapted to climbing on rocky cliffs.

Darwin’s Finches Darwin found finches around the islands that

had beak types that were specific to the types of food available.

*Those with big thick beaks ate seeds that were available.

*Those with smaller beaks ate the soft flesh of fruit or insects.

Darwin’s Finches

Origin of Evolutionary Thought

Charles Darwin developed the central idea of evolution by natural selection, but others before and during his time also built essential parts of the theory.

James Hutton 1785

Proposes that Earth is shaped by forces that took place over extremely long periods of time.

Proposed Earth to be millions of years old.

Thomas Malthus1798

Human populations will grow faster than the space and food supplies needed to sustain it.

– Competition

Jean-Baptiste Lamarck1809

Publishes his hypothesis of the inheritance of acquired traits.– Ideas were flawed.– The first to propose a

mechanism explaining how organisms change over time.

Charles Lyell1833

Publishes Principles of Geology

Explains that processes occurring now have shaped Earth’s geological features over long periods of time.

Alfred Wallace1858

Independently drew the same

conclusion as Darwin. Evolution by Natural Selection Conferred with Darwin about

ideas.

On the Origin of Species

Published in 1859 Proposed a mechanism

for evolution called Natural Selection– Organisms changed over time as a result of the

change to their environment. – Those best suited for their

environment would survive

and pass on their traits.