Thanks to a pair of University of Houston researchers who found a possible new solution to a 163-year-old puzzle, ecological factors can now be added to physiology to explain why animals grow bigger in the cold.
Their results were published in the February issue of the American Naturalist, offering new insight to Bergmann's rule that animals grow larger at high, cold latitudes than their counterparts closer to the equator. While traditional explanations have been based on body temperature being the driving force of this phenomenon, this group of community ecologists hypothesize that better food makes high-latitude animals bigger.
Chuan-Kai Ho, a Ph.D. graduate from UH in ecology and evolution, his adviser and UH professor of biology and biochemistry Steven Pennings, and their collaborator Thomas Carefoot from the University of British Columbia opened up a new line of study into Bergmann's rule. The research program in Pennings' lab over the last decade has offered the most extensive work done on the general problem of latitudinal variation in plant-herbivore interactions. This latest finding from Pennings' groundbreaking research at UH on this subject came from one of Ho's doctoral dissertation chapters.
"Because the American Naturalist is one of the top journals in our field, publishing at this level is a mark of great success for a Ph.D. student," Pennings said. "It's also a reflection of the strength of our graduate program in the ecology and evolution division of UH's department of biology and biochemistry."
Ho, now a postdoctoral student at Texas A&M at Galveston's Armitage & Quigg Laboratory, also has another chapter from his UH dissertation on salt marsh food webs published in Ecology, another top journal in the field. Pennings received a doctoral dissertation improvement grant for Ho in 2007-2008 from the National Science Foundation that provided funding for Ho to run chemical analyses on leaves from different latitudes to assess their nutritional content.
Studying three different plant-eating species – grasshoppers, planthoppers and sea snails – collected from along the Atlantic coast to Japan, respectively, the researchers fed these herbivores plants from both high and low latitudes and found that they all grew better when fed plants from the higher latitudes. This indicates that Bergmann's rule could reflect that plants from high latitudes provide better food than those from low latitudes. These latest findings, according to Ho, indicate that studies of Bergmann's rule should consider ecological interactions in addition to the more traditional theories of physiology based on responses to temperature.
Over the years, work in Pennings' lab has shown that, although low-latitude plants are less nutritious and better protected by chemical defenses, they experience heavy damage from herbivores, which are more abundant at low latitudes. Future study, Pennings adds, should focus on why there are more herbivores at lower latitudes despite the lower-quality food sources. A likely explanation is that herbivore populations are limited at high latitudes by a short growing season and high death rates during cold winters.
"While the explanations discovered in our current study only apply to herbivores, it may be that carnivores and omnivores also might grow larger as a consequence of eating larger herbivores," Ho said. "Examining such patterns and underlying mechanisms in nature will help us understand what currently is going on and what might happen down the line to our ecosystems."
About the University of Houston
The University of Houston, Texas' premier metropolitan research and teaching institution, is home to more than 40 research centers and institutes and sponsors more than 300 partnerships with corporate, civic and governmental entities. UH, the most diverse research university in the country, stands at the forefront of education, research and service with more than 37,000 students.
About the College of Natural Sciences and Mathematics
The UH College of Natural Sciences and Mathematics, with 170 ranked faculty and approximately 4,500 students, offers bachelor's, master's and doctoral degrees in the natural sciences, computational sciences and mathematics. Faculty members in the departments of biology and biochemistry, chemistry, computer science, earth and atmospheric sciences, mathematics and physics conduct internationally recognized research in collaboration with industry, Texas Medical Center institutions, NASA and others worldwide.
For more information about UH, visit the university's Newsroom at http://www.uh.edu/news-events/.
To receive UH science news via e-mail, visit http://www.uh.edu/news-events/mailing-lists/sciencelistserv.php.
For additional news alerts about UH, follow us on Facebook at http://tinyurl.com/6qw9ht and on Twitter at http://twitter.com/UH_News
Lisa Merkl | EurekAlert!
Bioinvasion on the rise
15.02.2017 | Universität Konstanz
Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
22.02.2017 | Physics and Astronomy
22.02.2017 | Life Sciences
21.02.2017 | Earth Sciences