Natural selection and the communal rearing of pups in African wild dogs (Lycaon pictus)

Summary The contributions of adult (>18 months) and yearling (10–18 months) African wild dogs (Lycaon pictus), to raising pups were quantified at eight natal dens, where pups remain for their first three months of life.Adults between 2–6 years of age did most of the hunting, and the dominant male often made the first grab at fleeing prey. Yearlings contributed to the hunting but were reluctant to tackle large prey animals. Yearlings and breeding females had prior access to food. Yearlings and adults regurgitated comparable amounts of food, but in one pack watched at a time of food shortage, the yearlings failed to regurgitate and stole food from the pups.Dominant dogs chased predators, especially spotted hyenas (Crocuta crocuta) from the area of the den more frequently than other adults or yearlings chased predators. Mothers, particularly in the first six weeks post-partum, stayed and protected the pups when the pack hunted.There is a positive, but non-significant correlation between the number of adult helpers and the number of pups raised. However, the sex ratio bias towards males at birth suggests that male helpers (which predominate) usually increase pup survivorship. The roles of direct and indirect selection in the evolution of the helping behavior are discussed. Indirect selection has probably played an important role in the unusual post-reproductive survival of males and their helping behavior.Serengeti Wildlife Research Institute contribution number 284     

Changes in singing behavior of male black-capped chickadees (Parus atricapillus) following mate removal

We removed the mates of ten male black-capped chickadees (Pares atricapillus) during the nest-building period to determine the effect of female presence on dawn singing. During the first dawn chorus following mate removal, males sang significantly longer, increased movement within their territory, and increased the percentage of their territory covered while singing. After the female was returned, these parameters returned to the pre-removal values. Males did not alter the frequency range or modal frequency of their songs when the mate was removed, nor did they change the degree of frequency shifting in the fee-bee song. We conclude that dawn singing in the black-capped chickadee acts, in part, as an intersexual signal, and that the behavior of frequency shifting in the song may be directed more toward rival males than females. Correspondence to: K. Otter     

Differing Modes of Biotic Connectivity within Freshwater Ecosystem Mosaics

We describe a collection of aquatic and wetland habitats in an inland landscape, and their occurrence within a terrestrial matrix, as a “freshwater ecosystem mosaic” (FEM). Aquatic and wetland habitats in any FEM can vary widely, from permanently ponded lakes, to ephemerally ponded wetlands, to groundwater‐fed springs, to flowing rivers and streams. The terrestrial matrix can also vary, including in its influence on flows of energy, materials, and organisms among ecosystems. Biota occurring in a specific region are adapted to the unique opportunities and challenges presented by spatial and temporal patterns of habitat types inherent to each FEM. To persist in any given landscape, most species move to recolonize habitats and maintain mixtures of genetic materials. Species also connect habitats through time if they possess needed morphological, physiological, or behavioral traits to persist in a habitat through periods of unfavorable environmental conditions. By examining key spatial and temporal patterns underlying FEMs, and species‐specific adaptations to these patterns, a better understanding of the structural and functional connectivity of a landscape can be obtained. Fully including aquatic, wetland, and terrestrial habitats in FEMs facilitates adoption of the next generation of individual‐based models that integrate the principles of population, community, and ecosystem ecology.     

Evaluating multiple emission pathways for fixed cumulative carbon dioxide emissions from global-scale socioeconomic perspectives

Recent climate modeling studies have concluded that cumulative carbon emissions determine temperature increase, regardless of emission pathways. Accordingly, the optimal emission pathway can be determined from a socioeconomic standpoint. To access the path dependence of socioeconomic impacts for cumulative carbon emissions, we used a computable general equilibrium model to analyze impacts on major socioeconomic indicators on a global scale for 30–50 pathways with different emission reduction starting years, different subsequent emission pathways, and three different cumulative 2100 emission scenarios (emissions that meet the 2 °C target, the 2 °C target emissions plus 10 %, and emissions producing radiative forcing of 4.5 W/m²). The results show that even with identical cumulative emission figures, the resulting socioeconomic impacts vary by the pathway realized. For the United Nations 2 °C target, for example, (a) the 95 % confidence interval of cumulative global gross domestic product (GDP) is 1355–1363 trillion US dollars (2010–2100, discount rate = 5 %), (b) the cumulative GDP of pathways with later emission reduction starting years grows weaker (5 % significance level), and (c) emissions in 2100 have a moderate negative correlation with cumulative GDP. These results suggest that GDP loss is minimized with pathways with earlier emission reduction followed by more moderate reduction rates to achieve lower emission levels. Consequently, we suggest an early emission peak to meet the stringent target. In our model setting, it is desirable for emissions to peak by 2020 to reduce mitigation cost and by 2030 at the latest to meet the 2 °C target.     

Visual associative learning in two desert ant species

Visual cues are important navigational tools for many solitary foraging insects. In addition to information provided by path integration, desert ants learn and use visual cues for homing back to their nest. In this study, we compared the visually based learning of two desert ant species: the North African Cataglyphis fortis and the Australian Melophorus bagoti, each of which lives in ecologically similar but visually different environments. In our experiment, ants’ choice performance was measured by training foragers in a channel system. We used a decision box with two visual stimuli during their homebound trips, with one of the stimuli always being the correct one that provided thoroughfare. To determine any habitat effects on learning, we examined intraspecific comparisons in C. fortis with different nest surroundings. The intraspecific comparison in C. fortis revealed no differences in learning the task. In general, C. fortis showed little learning in our task and the results were similar for ants from barren and cluttered environments. Overall, M. bagoti learned the task faster and had a higher level of accuracy than C. fortis. One explanation for this species-specific difference could be that the cluttered habitat of M. bagoti favours the evolution of visual associative learning more so than the plain habitat of C. fortis.     

Thermal decomposition of guaiacol in sub- and supercritical water and its kinetic analysis

The conversion of biomass waste into resources as a recycling process is receiving increased interest due to the perceived need for a sustainable global carbon cycle and environmental considerations. Several treatment processes are being developed. Hydrothermal treatment is one of the most effective approaches, because water at high temperatures and high pressures behaves as a reaction medium with remarkable properties. In this work, the reaction behavior of guaiacol as a biomass model compound was studied in subcritical water at 483–563 K and in supercritical water at 653–673 K using a batch reactor. Guaiacol can be considered representative of the aromatic ring structures present in lignin, a major component of woody biomass. The chemical species formed in aqueous products were identified by gas chromatography/mass spectrometry and quantified using high-performance liquid chromatography. The effect of pressure and reaction time on the conversion process of guaiacol is discussed. The results obtained indicate that this method has potential for efficient organic waste conversion.     

Application of an ELISA for PCB 118 to the screening of dioxin-like PCBs in retail fish

A commercially available enzyme-linked immunosorbent assay (ELISA) kit was evaluated for the determination of toxic equivalents (TEQs) of dioxin-like polychlorinated biphenyls (PCBs) in retail fish. The ELISA was highly specific for 2,3',4,4',5-pentachlorobiphenyl (PCB 118), which is generally the most abundant dioxin-like PCB isomer found in fish. The quantitative limit of the ELISA (using 3,3',4'-trichloro-4-methoxybiphenyl as a surrogate standard for PCB 118) was 10 ng ml(-1) (125 pg assay(-1)) in the standard curve, corresponding to 50 pg PCB 118 g(-1) in the tested sample. Good recoveries of PCB 118 (78.7-112.3%) were obtained for spiked purified fish extracts according to the ELISA. Good linearity was also obtained in dilution tests using purified fish extracts. No significant interference of the matrix was observed in the ELISA when this purification procedure was used. Recovery tests in which PCB 118 was added to fish samples also resulted in acceptable recoveries (60.2-82.3%) in the ELISA following purification. The ELISA results for fish samples correlated well with the TEQ concentrations of dioxin-like PCBs obtained by high-resolution gas chromatography/high-resolution mass spectrometry (r = 0.92, n = 26). These data indicate that the ELISA kit is suitable for screening retail fish for the TEQs of dioxin-like PCBs.     

Remediation of cadmium contamination in paddy soils by washing with chemicals: selection of washing chemicals

The efficiencies of neutral salts, strong acids, and chelates were tested for extracting cadmium (Cd) from three paddy soils. The higher the selectivity of the cations of the added neutral salts toward soil adsorption sites, the lower the pH in the extracts and the more soil Cd could be extracted. In addition, soil carbon and nitrogen contents and mineral composition were closely associated with the amount of Cd extracted. Calcium chloride and iron(III) chloride were selected as wash chemicals to restore Cd-contaminated paddy soils in situ. Washing with calcium chloride led to the formation of Cd chloride complexes, enhancing Cd extraction from the soils. The washing also substantially decreased soil levels of exchangeable and acid-soluble Cd, which are the major forms of bioavailable Cd for rice (Oryza sativa L.). The optimum conditions for in situ soil washing were also determined for calcium chloride.