Adaptation, Reproductive Isolation, and New Species!

By Sheril Kirshenbaum | September 29, 2010 10:58 am

I’ve not previously posted about my husband’s research, but he’s got an amazing new paper out in PLoS Biology being covered by other bloggers too! David Lowry’s work demonstrates through experimentation–for the first time in nature–that a chromosomal inversion contributes to adaptation and, in turn, reproductive isolation. In other words, when a section of chromosome flips over it traps adapted genes.  By holding these adapted genes prisoner, the reversed chromosomal section then has the fuel it needs to spread across the land.  The consequence of its spread is reproductive isolation and potentially a new species.

Picture 1David’s an evolutionary plant geneticist interested in speciation–the environmental and geographic reasons that organisms become two separate species as well as the genetic basis of this process. Why does this matter? When scientists are able to understand adaptive genetic variation within a species, they will be able to do a better job predicting its response to shifting environmental conditions. (Pretty important, given the challenges of limited resources and a changing climate).

David’s research over much of the past decade has looked at the heterogeneity of California’s Mediterranean ecosystems. He focused on two ecotypes of the yellow monkeyflower, Mimulus guttatus. One is a coastal perennial  (pictured left) version while the other is an annual (pictured right) that’s found in inland habitats. David looked at how adaptation to environmental stresses such as drought and salt tolerance leads to reproductive isolating barriers between these annual and perennial types.

And here’s the cool part: David has discovered regions of the genome that contribute traits like flowering time, salt tolerance, anthocyanin production, and nutrient uptake between the coastal and inland ecotypes. He spent years crossing numerous individual plants to conduct an experiment that reversed the genetic information for these traits in both lines and then planted them back into coastal and inland habitats in California to test the effects of these gene differences in nature.  In this way, he was able to show that the chromosome inversion polymorphism (i.e. reversed chunk of chromosome), which is spread widely over North America, actually causes adaptation and reproductive isolation in nature.  While he does not know yet what piece of the inversion is responsible for this pattern, he speculates a number of the over 350 genes stuck in the inversion are involved.

Having watched David toil away in the field and laboratory for years, I am so excited to see this awesome comprehensive article published!

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About Sheril Kirshenbaum

Sheril Kirshenbaum is a research scientist with the Webber Energy Group at the University of Texas at Austin's Center for International Energy and Environmental Policy where she works on projects to enhance public understanding of energy issues as they relate to food, oceans, and culture. She is involved in conservation initiatives across levels of government, working to improve communication between scientists, policymakers, and the public. Sheril is the author of The Science of Kissing, which explores one of humanity's fondest pastimes. She also co-authored Unscientific America: How Scientific Illiteracy Threatens Our Future with Chris Mooney, chosen by Library Journal as one of the Best Sci-Tech Books of 2009 and named by President Obama's science advisor John Holdren as his top recommended read. Sheril contributes to popular publications including Newsweek, The Washington Post, Discover Magazine, and The Nation, frequently covering topics that bridge science and society from climate change to genetically modified foods. Her writing is featured in the anthology The Best American Science Writing 2010. In 2006 Sheril served as a legislative Knauss science fellow on Capitol Hill with Senator Bill Nelson (D-FL) where she was involved in energy, climate, and ocean policy. She also has experience working on pop radio and her work has been published in Science, Fisheries Bulletin, Oecologia, and Issues in Science and Technology. In 2007, she helped to found Science Debate; an initiative encouraging candidates to debate science research and innovation issues on the campaign trail. Previously, Sheril was a research associate at Duke University's Nicholas School of the Environment and has served as a Fellow with the Center for Biodiversity and Conservation at the American Museum of Natural History and as a Howard Hughes Research Fellow. She has contributed reports to The Nature Conservancy and provided assistance on international protected area projects. Sheril serves as a science advisor to NPR's Science Friday and its nonprofit partner, Science Friday Initiative. She also serves on the program committee for the annual meeting of the American Association for the Advancement of Science (AAAS). She speaks regularly around the country to audiences at universities, federal agencies, and museums and has been a guest on such programs as The Today Show and The Daily Rundown on MSNBC. Sheril is a graduate of Tufts University and holds two masters of science degrees in marine biology and marine policy from the University of Maine. She co-hosts The Intersection on Discover blogs with Chris Mooney and has contributed to DeSmogBlog, Talking Science, Wired Science and Seed. She was born in Suffern, New York and is also a musician. Sheril lives in Austin, Texas with her husband David Lowry. Interested in booking Sheril Kirshenbaum to speak at your next event? Contact Hachette Speakers Bureau 866.376.6591 info@hachettespeakersbureau.com For more information, visit her website or email Sheril at srkirshenbaum@yahoo.com.

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