Download Evidence for Evolution Evidence for Evolution Direct Observation

1/21/2011
Evidence for Evolution
• Darwin’s book (1859)
Evidence for Evolution
January 20th, 2011
Direct Observation
– Over 500 pages
– Contained Darwin’s reasoning, as well as many examples
as well as many examples
– Much new evidence in last 150 years
Direct Observation
• Example 2:
– Drug‐resistant HIV
• Example 1:
– Guppies (Poecilia reticulata) in Trinidad 15 Generations
• Highly variable male coloration
• Females prefer bright males
• Predators find brighter males more easily
• Transplant drably colored males to a pool with low predator pressure
• HIV uses reverse transcriptase
• The drug 3TC substitutes for cytosine
• Transcription is terminated
Transcription is terminated
Only adaptive when 3TC present
Without 3TC, detrimental
Natural selection doesn’t create, only selects
Direct Observation Example 3:Birds introduced to islands
MORPHOLOGICAL EVOLUTION OF BIRDS RECENTLY INTRODUCED TO ISLANDS
RECENTLY INTRODUCED TO ISLANDS: PATTERNS OF DIVERSIFICATION Ph.D. Presentation
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Great Kiskadee
on Bermuda
• 200 introduced in 1957
• Supposed to eat lizards
that eat beetles that eat scale insects that attack endemic tree
scale insects that attack endemic tree
• Quickly spread to all parts of the island
Island Rule
• Large‐bodied species get smaller on islands, small‐bodied species get larger
• Mammals (Foster, 1964, 1965)
• Other groups Oh
(Lomolino, 2005), including birds (Clegg & Owens, 2002)
• “Point of no change” estimated to be 70 to 120 grams for birds (Lomolino, 2005)
© Claus Holzapfel
© Howard B. Eskin
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Island Rule Hypothesis
• Kiskadee < 70 grams
• Therefore, body size should increase on Bermuda
Field Methods
Bird Morphology
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Kiskadee Results
Character
Bermuda
Trinidad
% Larger
Mass (grams)
62.7 ± 0.52
59.8 ± 0.69
4.9
Wing Chord
109.8 ± 0.42
108.1 ± 0.53
1.5
Head Length
55 49 ± 0.17
55.49 0 17
54 96 ± 0.21
54.96 0 21
10
1.0
Bill Depth
8.68 ± 0.04
8.53 ± 0.04
1.7
Bill Width
9.84 ± 0.06
9.50 ± 0.06
3.7
Tarsus Length
24.69 ± 0.12
24.26 ± 0.17
1.8
Kiskadees are larger on Bermuda
Characters are heritable (0.2 < h2 < 0.6)
Summary of Part 1
• Kiskadees on Bermuda follow the Island Rule
• Part 2: Do other exotic birds?
Museum Visits
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Island Rule Hypothesis
• All birds I examined < 70 grams
• Therefore, body size should increase on islands
A
fi
ri
ii
ci
a
Asia
South
America
i
North America
Europe
Data Set
• 38 exotic populations
– Average of ~39 individuals/population
Bermuda
4
Big Puerto Kauai Maui Oahu
Mauritius Jamaica
Island
Rico
8
4
2
11
7
1
1
• Compared to individuals from native range
– Average of ~28 individuals/population
7 increases : 3 decreases P = 0.34
Not the Island Rule, but...
Summary of Part 2
Character
# of Changes P value
• May be losing Increase
19
Tail adaptations for <0.001
Length
Decrease
2
dispersal ability, Increase
2
Wing <0.001
in favor of agility Chord
in favor of agility
Ch d
Decrease
19
• Exotic birds on these islands do not follow the Island Rule
• However, some characters (wing and tail) have evolved
Culmen Length
Increase
6
Decrease
10
Bill Depth
Increase
4
Decrease
12
Increase
11
Decrease
4
Bill Width
• Part 3: Diverged from source, maybe from each other?
g
, y
0.455
0.077
0.118
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b
• 132 between‐island comparisons
– 38 showed divergence
Species
% Diverging
Character
% Diverging
83
Mass
70
Wing Chord
43
50
3 islands x 6 characters = 18 between‐island comparisons
15 / 18 different = 83%
Island
Mass
Tail Wing Length Chord
Head Culmen Bill Length Length
Depth
Bill Width
Tarsus Length
Culmen Length
29
24
Bill Width
24
17
Tail Length
19
Bill Depth
17
Tarsus Length
11
Head Length
0
9
Maui
0
Oahu
Big Island
Summary of Part 3
• Exotic birds on Hawaii have diverged among islands
• Variability in divergence among species and characters
Acknowledgments
• Julie Lockwood
• My Committee (past and present): Rebecca Jordan, ) R b
J d
Peter Smouse, Dov Sax, & Peter Morin
• Marsha Morin
• Lockwood Lab: Ben, David, Julian, Orion, Karen, Bill, Tom, Alison, Oren
• Field Tech: Matt Sileo
• Friends: Amy, Elena, Jesse, Carrie, Aabir, Charlie, Holly, Dave, Kristen, Emilie, Ai, Wes, Zac, Brooke, Maria, Kenneth
• Family
• Funding: Teaching assistantships; nnGrant 8261‐07
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Acknowledgments
The Fossil Record
The Fossil Record
• Deeper down into the earth, fossil organisms become less similar to modern organisms
• Many species have become extinct
• Deeper down into the earth, fossil organisms become less similar to modern organisms
• Many species have become extinct
Homologies
• Similar characteristics due to shared ancestry
Homologies
• Similar characteristics due to shared ancestry
Vestigial Structures
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Homologies
Homologies
• Homologies can be used to infer relatedness
• Similar characteristics due to shared ancestry
• Genetic Material
– DNA, RNA
– Not only same molecules
N
l
l l
Biogeography
Convergent Evolution
• Geographical distribution of life
• Why are some species here but not there?
• Natural Selection for similar ecology/life history
• Unrelated species similar
Peruvian Diving‐Petrel
lochfitty
Yellow‐throated Longclaw
Eastern Meadowlark
Jim “Jersey Birder”
Razorbill
Biogeography
• Geographical distribution of life
• Why are some species here but not there?
Continental Drift
Dispersal
So is Darwinian Evolution “Just a Theory”?
• Evolution is a Theory in the scientific sense
– i.e., it has been repeatedly tested
there is a lot of evidence supporting it
• At
At present, there are no other explanatory t th
th
l t
theories with any scientific consensus
Hawaii Amakihi Adelaide’s Warbler
Endemic
Found only in one location
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