September 25, 2004

Studying the Effects of Global Warming on Genetic Diversity

What are some of the effects of Global Warming? Elizabeth Hadly, professor of biology at Stanford, is providing some an answers based on studying the middens of packrats. She and her students have been carrying on a study of the genetic record of voles and pocket gophers through periods that contained climatic warming. And what they've found is that periods of warming reduced the genetic diversity of these small creatures as their habitats became less habitable.

Packrats, also known as woodrats, have a remarkable propensity of collecting objects and storing them in specific places for generations upon generations. Some middens used by packrats can be up to 10000 years old. One midden that Dr. Hadly is excavating is in the Lamar Cave in Yellowstone National Park which is 3000 years old and nine meters deep. Found in the middens are the remains of fish, birds and mammals collected by the packrats. The biologists are combing the detritus to find the individual teeth, jaws and skulls of voles and gopher rats and using the time period of the fragments to examine the genetics of these small creatures through the 3000 years record.

That time span ranges over two climate "anomalies" probably triggered by changing activity in the Sun. The first was a period called the Medieval Warm Period, when the global climate was warmer than today, which began around 850 AD and lasted for 500 years. The second was a cool period, called the Little Ice Age, which followed for another 500 years.

Genetically, the most consequential period was the Medieval Warm period where the gene pools were severely slashed from the stress of the warmer, dryer weather which created a much harsher environment for the voles and pocket gophers.

The scientists also found that the genetic diversity of the pocket gopher was more severely affected by the warming period than that of the vole which shows that some animals are more capable of withstanding the stresses brought by the warming climate. The vole is a very active and wide-ranging creature and individuals from one group often encounter individuals from genetically diverse groups. The pocket gopher is more of a home body and does not encounter too many other pocket gophers outside of its neighborhood. During the warmer period, as the numbers of individuals dropped, so did the genetic diversity of the ones remaining. The effect was so dramatic that the genetic diversity of the pocket gophers are still not as great as before 850 AD.

This study gives us some idea about what will be the consequences of global warming on the life on earth. Some creatures will have a much harder time accommodating the change as their ability to adapt is reduced.

'The more genetic diversity you can get, the better off you are for adaptation in the future," [Dr. Hadly] says.

Dr. Hadly believes that the problems of our fragmented ecosystems can make this problem even worse according to this interview on KQED's forum. How many animals and plants will be extirpated in the next 100 years with the rising global temperature? When looking at this study, it is sobering to realize what 1 degree Centigrade caused, especially when we are facing temperature rises that are significantly greater.

Posted by Mary at September 25, 2004 10:04 PM | Science | Technorati links |

Oh, I never worry for us humans. We will prevail, along with our rats, virusus, chickens, cats, dogs, cows and some birds.
All the truly glorious manifestations, and millions of hidden wonders will be gone.
There will be no regeneration. The dominated world will be exclusive. Hell, the first of any new species will be hunted without protection.

Posted by: Richard W. Crews at September 25, 2004 11:39 PM

Global warming causes retardation of the intuitive and cognative regions of the human brain, especially among those who tout conservative views. This retardation leads to a sense of denial in the source of the affliction, i.e. the climate change itself.
In 2003, an extensive study was done comparing the cognative skills of a modern conservative radio talk show host with those of the immature Chilean Swamp Rat. The study found that, although the rodent was genetically inferior to the conservative human, it displayed superior behavior in refusing to consume its own waste.
In another test of its ability to reason, the rodent showed markedly greater decision-making skills when given a choice between its anus and a hole in the ground. The human subject could not make the distinction.
Dr. Ivan Chubabe, a noted ethno-surreal genetic researcher has concluded that this study proves that most forms of animal life on the Earth operate at a higher level than the target human subjects. Before any further conclusions can be made, Dr. Chubabe says that more tests need to be performed. The next set of test subjects will be harvested from the newsrooms of Fox News in New York and Washington DC.
Dr. Chubabe has indicated that extensive CAT scans will need to be taken in this group because they may have difficulty in finding enough brain material for any tissue sample.
"We may have to combine the sample we take from at least a dozen of them just to get enough to see under the microscope." Dr. Chubabe indicated.

Posted by: David Aquarius at September 27, 2004 12:07 AM