While climate change kills off many species, scientists havefound evidence that it brings genetic changes to others?andthose are the ones that stay healthiest. Can humans use thisinformation to make it through the upcoming climate changes?
Biologist Elizabeth A. Hadly studied two kinds of rodentsfound in Yellowstone National Park in Wyoming: voles andgophers. Both species have survived major climate change.She collected DNA from living animals and compared it withDNA from the teeth of fossilized specimens found in LamarCave. Hadly says, "It contains hundreds of thousands ofbones and represents a continuous fossil record dating back3,000 years. This timescale allows us to really investigatemicroevolution in a natural environment..."
She was especially interested in the animals that were aliveduring the Medieval Warm Period (from 850-1350 AD) and theLittle Ice Age (from 1350-1950). She found a decline in thepopulation of both species during the Medieval Warm Periodwhen their habitats dried up, and an increase during theLittle Ice Age when the climate was wetter. There was a 40%drop in the voles and a 50% drop in the gopher populationduring the warmer period, but both populations rosedramatically during the colder period.
But how does this work on the DNA level? When an isolatedpopulation shrinks, inbreeding increases, so survivingoffspring end up with similar DNA. This lack of geneticdiversity can jeopardize the entire population, because eachindividual inherits the same vulnerability to diseases.Hadly says, "When you decrease population size, you have thepotential of eliminating much genetic diversity. That's whathappened to pocket gophers during the Medieval Warm Period.We found that they underwent a population size reduction anda decline in genetic diversity, which is what you wouldpredict."
But voles had a different response to medieval warming.Hadly says, "They didn't show any reduction in geneticdiversity, even though they did show a reduction inpopulation size" because they routinely look for mates fromother colonies. Voles move around?and that actually resultsin an elevation of genetic diversity during the time thattheir population sizes are undergoing reduction."
She says, "There's a subtle message in this?about thepotential influence of warming on evolution?gophers haven'treally recovered from the Medieval Warm Period, which endedless than 1,000 years ago. That means gophers are notgetting any fresh, new genes from somewhere outside becausethey're isolated." So while both species survived bothglobal warming and an ice age, the animals that added newgenes to the mix ended up much healthier.
Alex Kirby writes in bbcnews.com that scientists drillingbeneath the bed of the Arctic Ocean say the area had asub-tropical climate until global warming hit 55 millionyears ago, creating a permanent climate flip in the area.Humans weren't alive then to produce greenhouse gases, butthe climate created a natural greenhouse effect, whichcaused large amounts of carbon dioxide.
Paleontologist Michael Kaminski says it?s happening again."We're seeing a mass extinction of sea-bottom-livingorganisms caused by these conditions. Moving forward intime, we see many species disappear. Only a few hardysurvivors endure the thermal maximum."
To find out how animals and plants are responding to globalwarming right now,clickhere, scroll down to the bottom and click on "View allentries."
Nobody keeps up with science like Linda Howe, and we nowhave videos of thedocumentariesthat made herfamous.Her first book of anomalies inbackin stock as well.
To learn more,clickhere and here.
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