1 Biston betularia 2 Distribution Map Biston betularia f typica 1700 1800 1900 2000 1600 1840 Distribution Map 3 Discovery Biston betularia f carbonaria 1848 Manchester UK ID: 433691
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Slide1
Last Time…
1Slide2
Biston betularia
2Slide3
Distribution Map
Biston betularia f.
typica 17001800
19002000
1600
1840 Distribution Map
3Slide4
Discovery
Biston
betularia f.
carbonaria
1848 - Manchester, UK
1700
1800
1900
2000
1600
4Slide5
1700
1800
1900
20001600
James W. Tutt
(1858-1911)
Manchester in 1843
5Slide6
Frequency of dark form
Centers of pollution
1950
1700
1800
19002000
1600
6
London
Manchester
GlasgowSlide7
Mystery Phenomenon
Part 2
7Slide8
Unpolluted vs. Polluted Forest
8Slide9
Unpolluted Woods & Moths
9Slide10
Polluted Woods & Moths
10Slide11
Three Theories
1. Physiological Response to
Changed Environment
2. Natural Selection 3. Mutation11Slide12
Three Theories
1’ . Lamarck’s Theory of
Acquired Inheritance
2’. Darwin’s Theory of Natural Selection 3’. De Vries’ Mutation Theory12Slide13
Lamarckian Inheritance
Jean Baptiste Lamarck
(1744-1829)
All creatures have a natural tendency to become more
complex.
C
hanges
in behavior can result in morphological changes inherited by offspring
13Slide14
Lamarckian Inheritance
Applied to the Mystery Phenomenon
Nicholas Cooke
(1818-1886)
This trend is the result of the moths adapting to environmental conditions that have led to a general darkening of their resting sites, such as pollution and increased humidity.
Individuals adapt to local circumstances and these changes are passed to their offspring.
1700
1800
1900
2000
1600
14Slide15
Natural Selection
Charles Darwin
(1809-1882)
There are small heritable variations within populations. Some variations give their possessors a better chance at surviving and reproducing.
Over time the favored variation will become more common.
15Slide16
Increase
of the dark
form
is due to crypsis or the protective advantage of dark color in soot- darkened environments.J.W. Tutt1858-1911)
Natural Selection
& the Mystery Phenomenon
1700
1800
1900
2000
1600
16Slide17
Natural Selection
& the Mystery Phenomenon
E.B. Ford
(1901-1988)
The spread of the dark form is due to its physiological superiority over the pale form.
The spread is limited to areas darkened by pollution owing to the handicap of dark coloration in unpolluted environments.
1700
1800
1900
2000
1600
17Slide18
Mutation Theory
Hugo De
Vries
(1848-1935)Speciation is the result of large discontinuous changes caused by mutations that produce offspring radically different than their parents.
18Slide19
Mutation
Theory
&
the Mystery PhenomenonHeslop Harrison(1881-1967)Lead salts in the pollutants covering the foliage of trees have mutagenic properties.
Exposure to these salts has led to this mutation.
1700
1800
1900
2000
1600
19Slide20
To Sum it Up…
20Slide21
Cooke’s Theory
Increasing
Pollution
21Slide22
Tutt & Ford’s Theory
Increasing
Pollution
22Slide23
Heslop Harrison’s Theory
Increasing
Pollution
23Slide24
What is a theory?
24Slide25
How do scientists choose between competing theories?
25