Download Explaining How Organisms Change Jean Baptiste de

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History- Explaining How Organisms Change
Jean Baptiste de Lamarck: Recognized that organisms changed
over time. He had three assumptions:
 Organisms change because of inborn urge to change.
 Organisms could alter their bodies by using them in new ways.
 Acquired characteristics were passed on to progeny.
James Hutton 1788: Challenged the contemporary beliefs dating the
Earth as around 2,000 to 4,000 years old. Proposed that rocks,
valleys, and mountains came about over much longer periods of time.
Volcanoes, heat, rain, and other natural forces were responsible for
current geological formations.
Charles Lyell 1830: Challenged contemporary scientific method. He
argued scientists must view past events in terms of current
observations. He was against scientific theory explaining the past
events of the earth because of the lack of supportive, observable
examples.
Darwin’s voyage on the Beagle: Darwin recorded a vast diversity of
life, he was impressed by the many different ways organisms survive
and produce offspring.
Darwin’s explanations: Darwin explained his thoughts on diversity
using specific terms:
 Fitness: The combination of physical traits and behaviors that
helps organisms survive and reproduce in their environment.
 Evolution: A long, slow, process of change in species over time.
 Common descent: If you look back far enough you see all species
have shared common ancestors.
 Adaptation: Inherited characteristics that increase an animal’s or
plant’s fitness for survival.
 Fossils: The preserved remains of ancient organisms.
Evolution via Natural Selection
The Basics
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Species have changed over time
A. The fossil record shows
a. Species that no longer exist
b. Species that are similar to those that exist
today
c. Species that have gradually changed
d. Species that “suddenly” appear/disappear
i. Gradualism- slow change over time
ii. Punctuated equillibria- long periods of
little change followed by short bursts of
rapid change.
B. Other evidence
a. Structural similarity among critters
i. Homologous structures-share a common
ancestry but not necessarily function.
(Human hand—Whale flipper)
ii. Analogous structures-same function
different ancestry. (Bird wing, butterfly
wing)
b. Geographical distribution of critters
c. Embryological similarity
d. Pattern of organism groupings-continental vs.
weather related similarity.
e. Molecular similarity among organisms
f. Direct observation both in the lab and in the
wild
i. Bacterial examples
ii. HIV,influenza
iii. Peppered moth
How do organisms change over time.
a. Variation exists among individuals in populations
b. Some variations help an organism to survive and
reproduce.
i. Adaptations-characteristics of critters that
help that critter to survive and reproduce
ii. Ex: hair, feathers, color, beak size, etc.
c. Critters that survive and reproduce will pass their
traits on to the next generation of critters. Those
critters that do not survive will not pass on their
characteristics.
d. Over time the critters change.
III. Descent with modification
a. The idea that all life is descended from a common
ancestral form(s).
b. Differences in organisms over time eventually lead
to new populations that have “branched off” from
the ancestral population.
Assignment- Use pages 307-319 in your text to complete the S&T
questions 1-4 within those pages in your notebook.