Selection pressure, the driving force of evolution, induces changes in the genetic composition of a population. It works like this: if insects inflict too much damage on plants, the plants can't reproduce as successfully. This sets up a situation in which any plants that, by chance, have inherited insect-deterring traits are at an advantage. Because of that advantage, such traits are likely to spread through the population, urged on by "pressure" from the insects.
Researchers Rachel Vannette and Mark Hunter investigated whether different genetic "families" of the common milkweed from a single population in Northern Michigan would respond differently to increasing carbon dioxide levels in the atmosphere and if so, how those responses might affect the plants' chances of being eaten by insects.
"Specifically, we examined the response of milkweed plants to elevated carbon dioxide in terms of plant growth, asexual reproduction, and the production of chemical and physical defenses," Vannette said. Although all plants grew larger in response to elevated carbon dioxide, and all plant families showed similar growth and reproductive responses, plant families responded differently to elevated carbon dioxide in their production of chemical and physical defenses against plant-eating insects.
In particular, their production of heart poisons called cardenolides differed. While some plant families responded to elevated carbon dioxide by increasing cardenolide production, most decreased production—by as much as 50 percent.
"That's a big difference if you're a caterpillar," said Vannette, who is a graduate student in Hunter's research group. Hunter is the Henry A. Gleason Collegiate Professor of Ecology and Evolutionary Biology. Because the insects that consume milkweed, including monarch caterpillars, choose their host plants carefully and select specific plants based on the plants' concentration of toxic compounds, these specialist insects can act as agents of selection on milkweed plants.
Countering the shift away from chemical defenses was a shift toward physical defenses and resistance. "The plants had tougher leaves, and they were better at tolerating herbivory by caterpillars—they grew back faster," Vannette said.
Taken together, the results provide evidence that in response to elevated carbon dioxide, genetically-based differences in plant defense mechanisms and the changing plant-insect interactions that result may influence how plants adapt to changing climate.
Will the plants' changing defense strategies help or hinder monarchs?
"We don't know yet," Vannette said, "but that's a question we're investigating."
The findings appear in the March issue of Global Change Biology.
Conducted at the U-M Biological Station near Pellston, Michigan, the research was funded by the National Science Foundation.
U-M Sustainability fosters a more sustainable world through collaborations across campus and beyond aimed at educating students, generating new knowledge, and minimizing our environmental footprint. Learn more at sustainability.umich.eduContact: Nancy Ross-Flanigan
Nancy Ross-Flanigan | EurekAlert!
Joint research project on wastewater for reuse examines pond system in Namibia
19.12.2016 | Technische Universität Darmstadt
Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.
Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering