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Evolutionary and computational biology. Science and society, creationism, science in the news.
Bjørn Østman
67 posts
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- November 30, 2008
- 12:00 AM
- 1,606 views
Watching multicellularity evolve before our eyes
by Bjørn Østman in Pleiotropy
Chlorella vulgaris is an asexual, unicellular green alga. It has been observed in the laboratory to maintain unicellularity for thousands of generations. Boraas and his collaborators (1998) kept Chlorella for two decades in this way. Then they decided to add a predator, Ochromonas vallescia, also a unicellular organism. It has a flagellum (a tail with which it can swim about), and it eats Chlorella. This is bad news for the Chlorella population, which thus experiences a shift in selective pressu........ Read more »
MARTIN E. BORAAS, DIANNE B. SEALE, & JOSEPH E. BOXHORN. (1998) Phagotrophy by a flagellate selects for colonial prey: A possible origin of multicellularity. Evolutionary Ecology, 12(2), 153-164. DOI: 10.1023/A:1006527528063
Z. D. Blount, C. Z. Borland, & R. E. Lenski. (2008) Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli. Proceedings of the National Academy of Sciences, 105(23), 7899-7906. DOI: 10.1073/pnas.0803151105
- November 9, 2008
- 12:00 AM
- 2,232 views
Head injury as a cause of ADHD
by Bjørn Østman in Pleiotropy
Head injury is not a causative factor of ADHD, but it may be a marker for subsequent diagnosis of ADHD.... Read more »
H. T Keenan, G. C Hall, & S. W Marshall. (2008) Early head injury and attention deficit hyperactivity disorder: retrospective cohort study. BMJ, 337(nov06 2). DOI: 10.1136/bmj.a1984
- November 5, 2008
- 12:00 AM
- 2,010 views
Homosexuality is catholic in the animal kingdom
by Bjørn Østman in Pleiotropy
Beetles, bisons, black swans, bonobos, dolphins, elephants, flamingos, fruit bats, fruit flies, giraffes, lions, lizards, macaques, orangutans, ostriches, penguins, sheep. What do these animals have in common?They are all homosexual. In fact, the list is much, much longer. Here is what Petter Bøckman has to say about it:No species has been found in which homosexual behaviour has not been shown to exist, with the exception of species that never have sex at allWe can thus safely conclude that the........ Read more »
K. E. LEVAN, T. Y. FEDINA, & S. M. LEWIS. (2008) Testing multiple hypotheses for the maintenance of male homosexual copulatory behaviour in flour beetles. Journal of Evolutionary Biology. DOI: 10.1111/j.1420-9101.2008.01616.x
- October 28, 2008
- 12:00 AM
- 1,166 views
Development shapes evolution in silico
by Bjørn Østman in Pleiotropy
Why are there so few extant phyla or basic body-plans? There are only about 35 phyla, and nine of them include 96% of all living species. There used to be many more, back in the early days of the cambrian explosion, so one has to wonder why so many phyla were singled out for extinction, and just a few have gone on to do very well.The usual way to learn about our evolutionary history is to look at fossils. Unfortunately, fossils don't tell us very much about how the organisms developed, and this ........ Read more »
Elhanan Borenstein, David C. Krakauer, & Carl T. Bergstrom. (2008) An End to Endless Forms: Epistasis, Phenotype Distribution Bias, and Nonuniform Evolution. PLoS Computational Biology, 4(10). DOI: 10.1371/journal.pcbi.1000202
- October 10, 2008
- 12:00 AM
- 2,008 views
Non-functional DNA conserved in evolution
by Bjørn Østman in Pleiotropy
When a stretch of DNA is really important for an organism, natural selection will make sure that it is not changed much from generation to generation. This is termed purifying selection, and whenever it is observed, the conserved DNA is responsible for some function that the organism can't do without.Conversely, when a stretch of DNA is observed to code for an important function in the organism, it is a pretty solid guess that it is highly conserved by purifying selection. Survival and/or reprod........ Read more »
McLean, Bejerano. (2008) Dispensability of mammalian DNA. Genome Research.
- October 7, 2008
- 12:00 AM
- 1,719 views
Evolution and pleiotropy
by Bjørn Østman in Pleiotropy
Pleiotropy is the effect of one gene affecting multiple traits, as when Drosophila genes are expressed in more than one place during embryogenesis. For a bunch of examples of that, seeRepression and loss of gene expression outpaces activation and gain in recently duplicated fly genes, Oakley, Østman, and Wilson, 2006, PNAS, 103, 11637.In my own work on computer simulations of epistatic interactions, it is clear that pleiotropy has the effect of changing the phenotype more per mutation than with........ Read more »
Herrel, Huyghe, Vanhooydonck, Backeljau, Breugelmans, Grbac, Van Damme, and Irschick. (2008) Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource. PNAS, 105(12). DOI: http://www.pnas.org/content/105/12/4792.abstract?sid
- October 6, 2008
- 12:00 AM
- 1,534 views
Natural Selection Fails to Optimize Mutation Rates
by Bjørn Østman in Pleiotropy
Rich Lenski's group published this paper in PLoS Computational Biology less than two weeks ago:Clune J, Misevic D, Ofria C, Lenski RE, Elena SF, Sanjuán, R. (2008). Natural Selection Fails to Optimize Mutation Rates for Long-Term Adaptation on Rugged Fitness Landscapes. PLoS Comput Biol 4(9). PLoS Computational Biology, 4 (9).In the Ph.D. program I'm in we are required to give a journal club talk once per semester (the result of which is that that's exactly how many we give), and I chose to do ........ Read more »
Clune J, Misevic D, Ofria C, Lenski RE, Elena SF, Sanjuán, R. (2008) Natural Selection Fails to Optimize Mutation Rates for Long-Term Adaptation on Rugged Fitness Landscapes. PLoS Comput Biol 4(9). PLoS Computational Biology, 4(9). DOI: http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1000187
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