evolution. fixed species concept u the creator had designed each and every species for a particular...
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Result
No evolution. Created the viewpoint that all species could be identified and
named (Taxonomy). A major factor in the Linnaeus
classification system.
Theory Fossils were the remains of
species lost due to catastrophe.
No new species originated; species could only be lost
over time. Result - No evolution.
James Hutton 1795 - Gradualism
Profound change is the cumulative product of slow, but continuous processes.
Result
The Earth must be VERY old. (much older than 6000 years of the fixed species concept). Idea that slow and subtle
processes can cause substantial change.
Jean Baptiste Lamarck
Published theory in 1809. Theory - Life changed from
simple to complex over
time.
Lamarck’s Mechanisms
1. Use and Disuse - Body parts used to survive become larger and stronger.
Body parts not used to survive deteriorate.
Lamarck’s Mechanisms
2. Acquired Characteristics Modifications acquired by
use/disuse were passed on to offspring.
Lamarck’s Mechanisms
3. Natural Transformation of Species ….species changed with every generation… extinction never occurred, organisms simply changed overtime.
Problems with Lamarck’s Theory
No knowledge of genetics. Acquired traits are not
transmitted offspring.
To Lamarck’s Credits
Did suggest correctly the role of fossils in evolution.
Did suggest that adaptation to the environment is a
primary product of evolution.
Result
Darwin's training and travel opportunities allowed him to formulate and support his ideas on Natural Selection.
Result - July 1, 1858
Dual presentation of the Wallace-Darwin ideas to the Linnaean Society of London.
Comment
Darwin best remembered for the theory because of his overwhelming evidence and because he published.
Darwinian View
History of life is like a tree with branches over time from a common source.
Current diversity of life is caused by the forks from common ancestors.
“The Origin of Species”
Documented the occurrence of evolution.
Suggested that the mechanism for evolution was Natural Selection.
Fact 2 - Most populations are normally stable in size.
Fact 3 - Natural Resources are limited (finite).
Inference 1
The large number of offspring must compete for the finite resources.
Result - Most offspring die.
More FactsFact 4 - No two individuals in a
population are exactly alike.
Fact 5 - Variation is inheritable.
Inference 2
Those individuals whose inherited characteristics fit them best to their environment survive and reproduce.
Inference 3
Offspring inherit the favorable characteristics. Populations shift over time as the favorable characteristics accumulate.
Nature
Determines which characteristics are favorable.
Determines who survives. Result - “Natural Selection”
Artificial Selection
When man determines the characteristics that survive and reproduce.
Result - the various breeds of animals and plants we’ve developed.
Evolution Success Measured By
Survival Reproduction Whoever lives long enough
and has kids is the “winner” in evolution.
Requirements
In order for Natural Selection to work, you must have: Long periods of time. Variations within a population.
Subtleties of Natural Selection
1. Populations are the units of Evolution.
2. Only inherited characteristics can evolve.
Comment
Acquired characteristics may allow a species to evolve "outside" of Natural Selection.
Ex: culture, learning
Evidences of Evolution
1. Biogeography
2. Fossils
3. Taxonomy
4. Comparative Anatomy
5. Comparative Embryology
6. Molecular Biology
Biogeography
The geographical distribution of species.
Problem: Species mixtures on islands Marsupials in Australia
Evolution Viewpoint
Biogeographical patterns reflect descent from the ancestors that colonized that area.
Fossils
Relics or impressions of organisms from the past.
Problem: Show changes over time from
simple to complex. Many fossils don't have
descendants.
Comments1. Fossilization is a rare event.2. Only hard parts fossilize well.3. Problem in finding fossils.4. Interpretation.5. Missing Links.
Comparative Anatomy Problems
1. Homologous Structures - Common "building plan” with divergent functions.
Mammal forelimbs
Comparative Anatomy Problems
2. Vestigial Organs - Rudimentary structures of marginal, if any, use.
Whale Legs
Comparative Embryology
Problem - closely related organisms go through similar stages in their embryonic development.
Ex: Gill pouches in vertebrates
Molecular Biology
Study of Evolution at the DNA or protein levels.
Problem - related species have similar DNA sequences.