The modern theory of biological evolution: an expanded synthesis

In 1858, two naturalists, Charles Darwin and Alfred Russel Wallace, independently proposed natural selection as the basic mechanism responsible for the origin of new phenotypic variants and, ultimately, new species. A large body of evidence for this hypothesis was published in Darwins Origin of Species one year later, the appearance of which provoked other leading scientists like August Weismann to adopt and amplify Darwins perspective. Weismanns neo-Darwinian theory of evolution was further elaborated, most notably in a series of books by Theodosius Dobzhansky, Ernst Mayr, Julian Huxley and others. In this article we first summarize the history of life on Earth and provide recent evidence demonstrating that Darwins dilemma (the apparent missing Precambrian record of life) has been resolved. Next, the historical development and structure of the modern synthesis is described within the context of the following topics: paleobiology and rates of evolution, mass extinctions and species selection, macroevolution and punctuated equilibrium, sexual reproduction and recombination, sexual selection and altruism, endosymbiosis and eukaryotic cell evolution, evolutionary developmental biology, phenotypic plasticity, epigenetic inheritance and molecular evolution, experimental bacterial evolution, and computer simulations (in silico evolution of digital organisms). In addition, we discuss the expansion of the modern synthesis, embracing all branches of scientific disciplines. It is concluded that the basic tenets of the synthetic theory have survived, but in modified form. These sub-theories require continued elaboration, particularly in light of molecular biology, to answer open-ended questions concerning the mechanisms of evolution in all five kingdoms of life.Dedicated to Prof. Dr. Dr. hc mult. Ernst Mayr on the occasion of his 100th birthdayThis revised version was published online in March 2004, with corrections to the caption of Figure 6.     

The varying effects of left–right ideology on support for the environment: Evidence from a Swedish survey experiment

Years of research show that left-leaning individuals are more supportive of environmental policies than right-leaning individuals. The explanation for the lower level of support among right-leaning individuals is their stronger preference for economic growth and lower acceptance of intervention in markets. However, recent cross-national studies have questioned whether the effect of ideology on environmental support is universal. A Swedish survey experiment shows that the effect of ideology varies greatly depending on how individuals think about the environment. Specifically, it demonstrates that if environmental support is contrasted with economic growth, then the effect of ideology is stronger as opposed to when environmental support is not juxtaposed with economic growth. Furthermore, among people who strongly perceive the environment as a left–right issue, there is a larger divide between left and right.     

Determination of specific gravity of municipal solid waste

This investigation was conducted to evaluate experimental determination of specific gravity (G_s) of municipal solid waste (MSW). Water pycnometry, typically used for testing soils was adapted for testing MSW using a large flask with 2000 mL capacity and specimens with 100–350 g masses. Tests were conducted on manufactured waste samples prepared using US waste constituent components; fresh wastes obtained prior and subsequent to compaction at an MSW landfill; and wastes obtained from various depths at the same landfill. Factors that influence specific gravity were investigated including waste particle size, compaction, and combined decomposition and stress history. The measured average specific gravities were 1.377 and 1.530 for as-prepared/uncompacted and compacted manufactured wastes, respectively; 1.072 and 1.258 for uncompacted and compacted fresh wastes, respectively; and 2.201 for old wastes. The average organic content and degree of decomposition were 77.2% and 0%, respectively for fresh wastes and 22.8% and 88.3%, respectively for old wastes. The G_s increased with decreasing particle size, compaction, and increasing waste age. For fresh wastes, reductions in particle size and compaction caused occluded intraparticle pores to be exposed and waste particles to be deformed resulting in increases in specific gravity. For old wastes, the high G_s resulted from loss of biodegradable components that have low G_s as well as potential access to previously occluded pores and deformation of particles due to both degradation processes and applied mechanical stresses. The G_s was correlated to the degree of decomposition with a linear relationship. Unlike soils, the G_s for MSW was not unique, but varied in a landfill environment due both to physical/mechanical processes and biochemical processes. Specific gravity testing is recommended to be conducted not only using representative waste composition, but also using representative compaction, stress, and degradation states.     

Public participation in municipal solid waste source-separated collection in Guilin,China: status and influencing factors

Currently, China is facing critical problems regarding the management of municipal solid waste (MSW). The failure of existing pilot programs in implementing MSW source-separated collection highlights the need to analyze the factors significantly influencing public participation in this activity. To this end, a comprehensive analysis of MSW source-separated collection in Guilin, which is representative of wider areas located in inland China and with a GDP around the national average, was conducted. The research consisted of in-person interviews involving a questionnaire and theoretical analyses in terms of public perception, public awareness, public attitude, and willingness to pay. The analytical results identify the status of waste source-separated collection and influencing factors in implementation, and provides exercisable suggestions for decision makers in both China and more generally in industrializing countries to design promotion programs and education campaigns.     

SAGEBRUSH RANGELAND HYDROLOGY AND EVALUATION OF THE SPUR HYDROLOGY MODEL1

ABSTRACT: An excellent hydrologic record on sagebrush range-land has been developed at the Reynolds Creek Experimental Watershed in southwestern Idaho. The objectives of this paper were two-fold: (1) to analyze and describe the hydrologic record (8–18 years) from four sagebrush watersheds (1–83 ha); and (2) to evaluate the hydrology component of SPUR, a comprehensive rangeland model. The watersheds represent a gradient in elevation (1180–1658 m) and precipitation (240–350 mm/yr). Runoff was a small fraction (> 2 percent) of the total water budget for all of the watersheds. It occurred very infrequently at the three lower elevation watersheds: Summit, Flats, and Nancy Gulch. At Lower Sheep, the highest elevation watershed, runoff occurred most years for a period of 1 to 17 weeks in the winter. Frozen soil combined with rainfall or snowmelt was associated with most of the runoff from Flats and Nancy Gulch. At Summit summertime thunderstorms produced all of the runoff. The average annual sediment yield from all of the watersheds was low (17–950 kg/ha). It was highest from Summit, which had well developed alluvial channels and very steep slopes. SPUR was able to simulate runoff with reasonable accuracy only at Summit, where frozen soils were not a factor. There was poor correlation between predicted and actual annual 8ediment loss. The model tended to overpredict evapotranspiration early in the growing season and underpredict it in the late summer.     

PRECIPITATION CATCH MEASURED BY TUE WYOMING SHIELD AND TUE DUAL-GAGE SYSTEM1

ABSTRACT: The Wyoming shield and dual-gage measuring systems were developed to measure all precipitation, but more specifically snowfall under windy conditions. Results of a study at five sites on the Reynolds Creek Experimental Watershed in southwest Idaho indicate that gages with Wyoming shields and the dual-gage system measured the same amount when air temperatures were higher than ?2.2°C. Precipitation amounts computed from the dual. gage system were slightly more than from gages with Wyoming shields for snowfall, especially under windy conditions. Results also show how well the Alter shielded and unshielded gages used in the dual-gage system represent the computed catch if data were only available from one or the other of the gages.     

Comparison of emissions estimates derived from atmospheric measurements with national estimates of HFCs,PFCs and SF6

This paper assesses the feasibility of using atmospheric measurement of fluorinated greenhouse gases (HFCs, PFCs and SF6) for the review and verification of greenhouse gas inventories provided by national governments. For this purpose, available data were compiled. It was found that atmospheric measurements of these gases are available and provide an indication of global annual emissions with sufficient certainty to reach the following conclusions: Within the uncertainty of the method, it was found that emissions of HFC-23, a by-product of HCFC-22 production, as obtained from atmospheric measurements did not decrease as fast, as the countries have reported. In contrast, SF6 concentrations in the atmosphere suggest higher emissions than reported by countries. Regional emission estimates from atmospheric measurements are still in a more pioneering state and cannot be compared to national estimates. Intensified efforts to measure HFCs, PFCs and SF6 in the atmosphere are recommended.     

Evaluating the policy to restrict the potentially invasive black carp (Mylopharyngodon Piceus): A decision protocol with assurance bonding

The introduction of potentially invasive species is a concern to the public and the aquaculture industry. Used to protect channel catfish from infectious trematode infestations, the non-indigenous black carp has been evaluated by the US Fish and Wildlife Service (USFWS) and deemed potentially ‘injurious’ under the terms of the Lacey Act. Consequently, the black carp may be restricted from interstate commerce and eventually removed from US waters. An alternative approach to evaluating the risks posed by invasive species is considered and compared to that used by the USFWS. Short of outright restriction, reasonable options for management of such invasive species probably exist, including better use of environmental assurance bonds and return-deposit models.     

The Effect of Shoreline Recreational Angling Activities on Aquatic and Riparian Habitat Within an Urban Environment: Implications for Conservation and Management

There is growing concern that recreational shoreline angling activity may negatively impact littoral and riparian habitats independent of any direct or indirect influences of fish harvest or fishing mortality through mechanisms such as disturbance (e.g., trampling, erosion) and pollution (e.g., littering). We sampled a suite of aquatic and terrestrial variables (i.e., water quality, aquatic and terrestrial macrophytes, soil compaction, anthropogenic refuse) at 14 high shoreline angling-activity sites (identified by way of interviews with conservation officers and angling clubs) within an urban area (Ottawa, Canada). For each high angling-activity site, a nearby corresponding low angling-activity site was sampled for comparison. We found that the percentage of barren area and soil compaction were greater in areas of high angling activity compared with areas that experienced relatively low angling activity. In addition, terrestrial and aquatic macrophyte density, height, and diversity were lower at high angling-activity sites. Angling- and non-angling-related litter was present in large quantities at each of the high angling-activity sites, and comparatively little litter was found at low angling-activity sites. Collectively, these findings indicate that shoreline angling does alter the riparian environment, contributing to pollution and environmental degradation in areas of high angling intensity. With growing interest in providing urban angling opportunities and in response to increasing interest in developing protected areas and parks, a better understanding of the ecologic impacts of shoreline angling is necessary to address multiuser conflicts, to develop angler outreach and educational materials, and to optimize management of angling effort to maintain ecologic integrity of riparian and aquatic ecosystems.