March 2012: Evolution in real time.
It is normal to think of evolution occurring over long periods of time, millions or perhaps hundreds of millions of year; this is appropriate for evolution of humans, dinosaurs, etc. These extreme times make it seem impossible to observe evolution in real time, i.e. in the career of a single scientist.
However, it is possible to observe evolution in real time by focusing on relatively small changes. There are some beautiful studies of changes in the beaks of finches living on the Galapagos Islands over only a few years as the birds adapt to changes in climate. There have also been many studies of the evolution of the spines of the stickleback fish that live in lakes in Africa. What might seem to be big changes in a species, because the morphology has changed dramatically, might if fact be due to only a few genetic changes in key gene complexes, such as the homeobox, which is mentioned in Life on the Dock (LOTD), page 133.
Another way to study evolution in real time is to take advantage of the fact that the evolutionary time scale is proportional to the generation time of a species: the time between one generation and the next.
2011 summer meeting of the European Society for Evolutionary Biology
Results of some real time evolutionary studies were reported at this meeting, and a summary was published in the journal Science, [1].
Bacteria are a good organism to study evolution in real time, since bacteria divide every 30-90 minutes in rich media. Many interesting and revealing experiments have been done to reveal the progress of evolution in bacteria [2]. Ongoing work in Lenski's lab was presented at the ESEB meeting. Some people don't think of bacteria as "real" organisms, but they are as real as you and me.
Yeast are another class of organism that can easily be used for real-time evolution studies, since they produce new generations every 60-120 minutes. The major difference between yeast and bacteria is that yeast are eukaryotes, i.e. they have a true nucleus like we do. The Science review article describes the work of Travisano and Ratcliff on the evolution of multicellular yeast "clumps", which are a precursor to multicellular "organisms" that exhibit many of the properties of multicellular organisms (like you and me) have. It might seem that the transition to a multicellular organism would be a major event, but it seems it has occurred many times. A major requirement is the evolution of suicide in individual cells. Cell suicide has a specific name: apoptosis (described on page 69 and 73 of LOTD).
Graham Bell has studied the evolution of the algae Chlamydomonas to grow in the dark (the parental species requires light). After 5 years they can isolate species that grow in the dark.
Aneil Agrawal studies the evolution of rotifers in culture (see page 44 in LOTD). They have found that sex frequently appears in cultures, but then is often lost. Sex seems to appear most frequently in environments that periodically change.
References
1. Evolutionary Time Travel, Pennisi: Science vol 334, pg 893, 18 Nov 2011
2. Test Tube Evolution Catches Time in a Bottle, Appenzeller: Science vol 284, pg 2108, 25 June1999
Access to articles in Science via the Internet: The present policy of Science is that the abstracts of all articles are free, and the entire contents are free if the article has been published more than one year earlier, but not before 1997. Why the 1997 limit? Sounds crazy to me, but I don’t have any influence with Science.