University of Georgia

About: University of Georgia is a education organization based out in Athens, Georgia, United States. It is known for research contribution in the topics: Population & Gene. The organization has 41934 authors who have published 93622 publications receiving 3713212 citations. The organization is also known as: UGA & Franklin College.

Herbivore-infested plants selectively attract parasitoids

Abstract: 1-3 . Here we use chemical and behavioural assays to show that these plant emissions can transmit herbivore-specific infor- mation that is detectable by parasitic wasps (parasitoids). Tobacco, cotton and maize plants each produce distinct volatile blends in response to damage by two closely related herbivore species, Heliothis virescens and Helicoverpa zea. The specialist parasitic wasp Cardiochiles nigriceps exploits these differences to distinguish infestation by its host, H. virescens, from that by H. zea. The production by phylogenetically diverse plant species and the exploitation by parasitoids of highly specific chemical signals, keyed to individual herbivore species, indicates that the interaction between plants and the natural enemies of the herbi- vores that attack them is more sophisticated than previously realized. Herbivore-induced plant signals are important for the foraging success of parasitoids and for the plants' defence 3-8 . The production and release of volatiles is triggered at least in part by substance(s) in the oral secretion of herbivores 2,9 ; in cotton, this is known to be an active process in which several terpenoids are synthesized de novo in response to insect feeding 10 . The chemical composition of released volatiles varies among plant tissues (cotton leaves, flowers and bolls, for example) 11 , varieties 12 and cultivars 13 . Although volatile emis-

Research Commentary---Platform Evolution: Coevolution of Platform Architecture, Governance, and Environmental Dynamics

Abstract: The emergence of software-based platforms is shifting competition toward platform-centric ecosystems, although this phenomenon has not received much attention in information systems research. Our premise is that the coevolution of the design, governance, and environmental dynamics of such ecosystems influences how they evolve. We present a framework for understanding platform-based ecosystems and discuss five broad research questions that present significant research opportunities for contributing homegrown theory about their evolutionary dynamics to the information systems discipline and distinctive information technology-artifact-centric contributions to the strategy, economics, and software engineering reference disciplines.

The NextGen Model Atmosphere Grid for 3000 ≤ Teff ≤ 10,000 K

Abstract: We present our NextGen Model Atmosphere grid for low-mass stars for effective temperatures larger than 3000 K. These LTE models are calculated with the same basic model assumptions and input physics as the VLMS part of the NextGen grid so that the complete grid can be used, e.g., for consistent stellar evolution calculations and for internally consistent analysis of cool star spectra. This grid is also the starting point for a large grid of detailed NLTE model atmospheres for dwarfs and giants. The models were calculated from 3000 to 10,000 K (in steps of 200 K) for 3.5{le}logthinspg{le}5.5 (in steps of 0.5) and metallicities of {minus}4.0{le}[M/H]{le}0.0. We discuss the results of the model calculations and compare our results to the Kurucz grid. Some comparisons to standard stars like Vega and the Sun are presented and compared with detailed NLTE calculations. {copyright} {ital {copyright} 1999.} {ital The American Astronomical Society}