International Institute for Applied Systems Analysis

About: International Institute for Applied Systems Analysis is a nonprofit organization based out in Laxenburg, Austria. It is known for research contribution in the topics: Population & Greenhouse gas. The organization has 1369 authors who have published 5075 publications receiving 280467 citations. The organization is also known as: IIASA.

Evolutionary Branching and Sympatric Speciation Caused by Different Types of Ecological Interactions.

Abstract: Evolutionary branching occurs when frequency-depen- dent selection splits a phenotypically monomorphic population into two distinct phenotypic clusters. A prerequisite for evolutionary branching is that directional selection drives the population toward a fitness minimum in phenotype space. This article demonstrates that selection regimes leading to evolutionary branching readily arise from a wide variety of different ecological interactions within and between species. We use classical ecological models for symmetric and asymmetric competition, for mutualism, and for predator-prey interactions to describe evolving populations with continuously vary- ing characters. For these models, we investigate the ecological and evolutionary conditions that allow for evolutionary branching and establish that branching is a generic and robust phenomenon. Evo- lutionary branching becomes a model for sympatric speciation when population genetics and mating mechanisms are incorporated into ecological models. In sexual populations with random mating, the continual production of intermediate phenotypes from two incipient branches prevents evolutionary branching. In contrast, when mating is assortative for the ecological characters under study, evolutionary branching is possible in sexual populations and can lead to speciation. Therefore, we also study the evolution of assortative mating as a quantitative character. We show that evolution under branching con- ditions selects for assortativeness and thus allows sexual populations to escape from fitness minima. We conclude that evolutionary branching offers a general basis for understanding adaptive speciation and radiation under a wide range of different ecological conditions.

Continuity in evolution: on the nature of transitions.

Abstract: To distinguish continuous from discontinuous evolutionary change, a relation of nearness between phenotypes is needed. Such a relation is based on the probability of one phenotype being accessible from another through changes in the genotype. This nearness relation is exemplified by calculating the shape neighborhood of a transfer RNA secondary structure and provides a characterization of discontinuous shape transformations in RNA. The simulation of replicating and mutating RNA populations under selection shows that sudden adaptive progress coincides mostly, but not always, with discontinuous shape transformations. The nature of these transformations illuminates the key role of neutral genetic drift in their realization.

Vulnerability of US and European electricity supply to climate change

Abstract: Thermoelectric power in Europe and the United States is vulnerable to climate change. Here research relates lower summer river flows and higher river water temperatures as a result of climate change to thermoelectric plant capacity. Summer average capacity can decrease by 6.3–19% in Europe and 4.4–16% in the United States, depending on the cooling system type and climate scenario for 2031–2060.

Global and regional evolution of short-lived radiatively-active gases and aerosols in the Representative Concentration Pathways

Abstract: In this paper, we discuss the results of 2000–2100 simulations following the emissions associated with the Representative Concentration Pathways (RCPs) with a chemistry-climate model, focusing on the changes in 1) atmospheric composition (troposphere and stratosphere) and 2) associated environmental parameters (such as nitrogen deposition) In particular, we find that tropospheric ozone is projected to decrease (RCP26, RCP45 and RCP6) or increase (RCP85) between 2000 and 2100, with variations in methane a strong contributor to this spread The associated tropospheric ozone global radiative forcing is shown to be in agreement with the estimate used in the RCPs, except for RCP85 Surface ozone in 2100 is projected to change little compared from its 2000 distribution, a much-reduced impact from previous projections based on the A2 high-emission scenario In addition, globally-averaged stratospheric ozone is projected to recover at or beyond pre-1980 levels Anthropogenic aerosols are projected to strongly decrease in the 21st century, a reflection of their projected decrease in emissions Consequently, sulfate deposition is projected to strongly decrease However, nitrogen deposition is projected to increase over certain regions because of the projected increase in NH3 emissions

Climate change mitigation through livestock system transitions

Abstract: Livestock are responsible for 12% of anthropogenic greenhouse gas emissions. Sustainable intensification of livestock production systems might become a key climate mitigation technology. However, livestock production systems vary substantially, making the implementation of climate mitigation policies a formidable challenge. Here, we provide results from an economic model using a detailed and high-resolution representation of livestock production systems. We project that by 2030 autonomous transitions toward more efficient systems would decrease emissions by 736 million metric tons of carbon dioxide equivalent per year (MtCO2e⋅y(-1)), mainly through avoided emissions from the conversion of 162 Mha of natural land. A moderate mitigation policy targeting emissions from both the agricultural and land-use change sectors with a carbon price of US$10 per tCO2e could lead to an abatement of 3,223 MtCO2e⋅y(-1). Livestock system transitions would contribute 21% of the total abatement, intra- and interregional relocation of livestock production another 40%, and all other mechanisms would add 39%. A comparable abatement of 3,068 MtCO2e⋅y(-1) could be achieved also with a policy targeting only emissions from land-use change. Stringent climate policies might lead to reductions in food availability of up to 200 kcal per capita per day globally. We find that mitigation policies targeting emissions from land-use change are 5 to 10 times more efficient--measured in "total abatement calorie cost"--than policies targeting emissions from livestock only. Thus, fostering transitions toward more productive livestock production systems in combination with climate policies targeting the land-use change appears to be the most efficient lever to deliver desirable climate and food availability outcomes.