Transcript PowerPoint Presentation - Clonal interference is a phenomenon in

LONG-TERM
EVOLUTIONARY
EXPERIMENTS
CHAPTER 6
http://natsci.edgewood.edu/wingra/Student%20Projects%2
02008/E.%20Coli/default.htm
ADAPTIVE RADIATION STUDIES PROVIDE LIMITED
INFORMATION AS TO WHY IT HAPPENED AND WHAT
OTHER POSSIBILITIES MAY HAVE BEEN POSSIBLE.
http://news.nationalgeographic.com/news/bigphotos/83795719.html
CLASSICAL STUDIES: GALAPAGOS FINCHES,
AFRICAN CICHLIDS, STICKLEBACKS
THE THEORY OF EVOLUTION BY NATURAL SELECTION PROVIDES A
CAUSE-AND-EFFECT FRAMEWORK (EVEN MATHEMATICALLY) BUT
NOT THE MECHANISMS.
SHORT-TERM SELECTION VERSUS • Long-term studies are
LONG-TERM STUDIES
SHORT-TERM
• limited number of generations
• Can lead to erroneous inferences
regarding genetic correlations
LONG-TERM
• Association of organism and
environment is open-ended
• Direct investigation of why an
adaptation happened (causality)
• Model organisms - insects
(Drosophila) or microbes
(E. coli)
able to study the
importance of chance
impacts on adaptation
www.nature.com
http-//louisproyect.wordpress.com
CLONAL INTERFERENCE
MAINTAINS DIVERSITY
Periodic selection : natural
selection recurrently purges
diversity within a bacterial
population
Recombination in bacteria is rare
Diversity is generally transient
Larger populations (possible via
long-term studies) >>
multiple beneficial
mutations>> diversity persists
3 ways ( Dr. Bennett)
http-//www.nature.com/nrg/journal/v4/n6/box/nrg1088_BX2
ADAPTIVE RADIATION:
Trade-off between resource
breadth and competitive ability
• Organism may be
good at using one
resource and not
another>>>leads
to co-existence of
species
http://natsci.edgewood.edu/wingra/Student%20Projects%202008/E.%20Coli/default.htm
SUMMARY
Long-term studies
• direct observation of
adaptation
• mechanisms of
adaptation
• evaluation of
environmental and
genetic factors
• causality of evolutionary
change
References
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http://abcnews.go.com/Technology/DyeHard/climate-change-find-tiny-sticklebackfish-evolved-temperatures/story?id=11368797
http://www.plosbiology.org/
http://www.biomedcentral.com/1471-2148/10/11
http://beaker.biology.washington.edu/research/pubs/2002/Bohannan_et_al2002.pdf
http://www.hhmi.org/genesweshare/e120.html
http://www.nature.com
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http://www.nanobugs.com/
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http://www.ncbi.nlm.nih.gov
http://news.nationalgeographic.com/news/bigphotos/83795719.html
http://www.plosbiology.org/article/info:doi%2F10.1371%2Fjournal.pbio.1000250