Transcript Adaptive radiation

Adaptive radiation
The rapid diversification of a
lineage
The factors that drive adaptive
radiation
• key
innovations/mutations/novelty
• ecological opportunity
Examples of adaptive
radiation
Group
Key innovation(s)
The Cambrian explosion
The fossil record
• Ediacaran fauna
• Burgess shale
• 540-500 Mya
The molecular evidence
• Hemoglobin ‘clock’
Ecological underpinnings
• Increased atmospheric
oxygen
• Predator-prey
coevolution
• Global warming and
rising sea levels
following the most
extensive glaciations in
history
What does the molecular
clock say about the timing of
the Cambrian explosion?
Bruce Runnegar (1982): 900Mya
Wray et al. (1996): 10001200Mya
How can these molecular data
be reconciled with the fossil
data?
What observations or
experiments would shed light
on the cause of the
discrepancy?
The (pre?) Cambrian explosion
1200Mya
from Rasmussen et al. (2002) Science
What are these?
What are these?
What is this?
What are these?
What are these?
What is this?
Phylogeny
Adaptation
Tarweed huggers
Larry = Gerry Carr (U Hawaii)
Moe = Robert Robichaux (U AZ)
Curly = Bruce Baldwin (UC Berkeley)
http://www.botany.hawaii.edu/faculty/carr/silversword.htm
Adaptive radiation in
real time
Paul Rainey and Mike
Travisano (1998) Nature 394:
69-72.
Adaptive radiation in bacteria
(Pseudomonas) grown in
liquid culture (microcosm)
Why use bacteria for
evolutionary experiments?
Adaptive radiation in
real time
Two environments:
Homogeneous (shaken, not
stirred)
Heterogeneous (unshaken)
Replicate experiments founded
with a clonal isolate of the
‘smooth’ morph
Plated onto solid agar media at
daily intervals to measure
frequency of morphotypes
Pseudomonas
Pseudomonas
Pseudomonas
Pseudomonas