1. I. Lamarkian Evolution
A. Jean-Baptiste Lamarck
1. Early evolutionary biologist who tried to explain how organisms
change over time
2. Lamarck incorporated two ideas into his theory of evolution
Use and disuse – Individuals lose characteristics they do not require (or
use) and develop characteristics that are useful
Inheritance of acquired traits – Individuals inherit the traits of their
ancestors
3. According to Lamark, the theory of use and disuse
proposes how the long neck of giraffes came about
Evolution by Natural Selection andEvolution by Natural Selection and
Change Over TimeChange Over Time
3. II. Darwinian Evolution by Natural Selection
A. Theory of Evolution by Natural Selection
1. Darwin was greatly influenced by geologist, Charles Lyell
-Lyell wrote The Principles of Geology which popularized the idea that the
Earth’s geology was shaped by slow-moving forces still in operation today
-Lyell believed that the world is older than 300 million years, on the basis of
its geological anomalies
2. Darwin adopted the idea that as the Earth’s geology changes over time,
and living things adapt to the changing environment
Charles Darwin Charles Lyell Thomas Malthus
4. 3. Darwin was also influenced by Thomas Malthus’ writings- An Essay
on
the Principle of Population
-Malthus stated that human population would grow so large
someday, that eventually the population would outstrip the
supply of food
4. Malthus’ essay led Darwin to believe that since organisms produce
more offspring than could possibly survive, the overpopulation
would
result in a “struggle for existence” in which the fittest would survive
5. Darwin coined the term, “survival of the fittest”
5. C. Voyage of the HMS Beagle
1. Darwin opted to become ship’s naturalist on the HMS Beagle
2. His role was to study the flora and fauna of as the ship traveled
around
the world on its 5 year journey
3. When at the Galapagoes archipelago, he studied the life inhabiting the
13 islands
4. The island chain arose out of the ocean by volcanism about a million
years ago about 970 kilometers off the coast of Ecuador
5. The islands were never part of mainland South America and each of
the 13 islands were separated by water
6. The Galapagoes islands were inhabited by fauna and flora that shared
common characteristics related to, but not found on mainland South
America
7. Also, the fauna and flora were slightly different from island to island
8. To Darwin, this was the “cradle of evolution”
8. D. Darwin’s Finches
1. Darwin studied the 14 species of Galapagos Finches found on the
different islands
2. All 14 species of finches had the same drab plumages and nesting
habits indicating that they diverged from a common ancestor-
divergent evolution
3. The birds varied in size from 10 to 20 cm and weigh between 8 and
38 grams- the smallest is the warbler Finch and the largest is the
vegetarian Finch
4. The most important differences between species are in the size and
shape of their beaks, being highly modified and highly adapted to the
different food sources found on the different islands
5. When the ancestral Finches reached the islands from the mainland,
there was no competition- no birds to compete with
6. As they settled on the different islands, they adapted to the different
food sources, and with little or no competition
7.This allowed the original finch to flourished into 14 different species
11. E. Galapagos Tortoise
1. They are huge turtles that live on the 13 islands
2. They adapted to the different environments they were exposed to on
the islands
3. The shell size and shape vary between populations
4. On islands with humid highlands, the tortoises are larger, with domed
shells and short necks
5. On islands with dry lowlands, the tortoises are smaller, with "saddleback"
shells and long necks
6. These island-to-island differences of the finches and tortoises played a
key role in the development of Charles Darwin's theory of evolution by
natural selection
13. F. On the Origin of the Species by Natural Selection
1. As a result of years of work, in 1859, Darwin presented his theory of
evolution by natural selection as an explanation for adaptation and
speciation
2. He defined natural selection as the principle by which each slight
variation, if useful to the organism, is passed on to the next generation
3. Natural selection is one of the cornerstones of modern biology
Comparing Lamarkian evolution with
Darwinian evolution
25. E. Structural Homology- An Example of Divergent Evolution
1. Provides evidence of descent from a common ancestor:
2. Limbs with different functions: humerus, radius, ulna, carpal, phalanges
in vertebrates
26. F. Artificial Selection
1. Farmers and breeders allowed only the plants and animals with
desirable characteristics to reproduce
2. These common vegetables were cultivated from forms of wild mustard
27. 3. Through artificial selection, the wolf has given rise
to the many strains of the domesticated dog
28. G. Convergent Evolution
1. Independent evolution of similar features in species of different
lineages
2. The placental and marsupial mammals have adapted to similar
enviornments by developing similar anatomical features
29. 3. The fish, reptile and dolphin have fins and swim all "converged" on
swimming in water with fins independently
30. H. Industrial Melanism
A. The Peppered Moth- (Biston betularia)
1. The peppered moth is an example demonstrating how
natural selection can occur over a short period of time.
2. The evolution of the peppered moth over
the last two hundred years has been studied in detail
3. Originally, the vast majority of peppered moths had light
coloration, which effectively camouflaged them against the
light-colored trees upon which they rested
4. During the industrial revolution, due to widespread
pollution,
in England, the trees which peppered moths rested on
became blackened by soot, causing most of the light-colored
moths, or typica, to die off due to predation
31. 5. At the same time, the dark-colored moths, carbonaria, began to flourish
because of their ability to hide from predators on the darkened trees
6. If both typica and carbonaria peppered moths are resting on
trees with light colored bark, predatory birds will more easily
attack and kill the darker moths
7. Likewise if both typica and carbonaria peppered moths are
resting on trees with dark colored bark, predatory birds will
more easily attack and kill the lighter moths
8. By the mid-19th century, a shift in population developed as the
number of dark-colored moths became the dominant moth due the
industrial revolution
