Agonistic onset during development differentiates wild house mouse males (Mus domesticus)

Wild house mouse populations have been suggested to locally adapt to varying dispersal regimes by expressing divergent aggressivity phenotypes. This conjecture implies, first, genetic polymorphism for dispersive strategies which is supported by the finding of heritable variation for male dispersal tendency in feral house mice. Secondly, aggressivity is assumed to translate into dispersal rates. This speculation is reinforced by experimental evidence showing that non-agonistic males display lower dispersal propensity than same-aged males that have established agonistic dominance. However, the actual ontogenetic behavioural pattern and its variability among populations remain unknown. Hence, in this study the timing of agonistic onset is quantified within laboratory-reared fraternal pairs, and compared between descendants from two different feral populations. Males from the two populations (G and Z) differed strongly in agonistic development, as Z fraternal pairs had a 50% risk of agonistic onset before 23.5±2.7 days of age, while this took 57.3±5.4 days in males from population G. This difference coincided with significant genetic differentiation between the males of the two populations as determined by 11 polymorphic microsatellite markers. Furthermore, in population G, males from agonistic and amicable fraternal pairs exhibited significant genetic differentiation. These results corroborate the supposition of genetic variability for dispersive strategies in house mice, and identify the ontogenetic timing of agonistic phenotype development as the potential basis for genetic differentiation. This opens a unique opportunity to study the genetic determination of a complex mammalian behavioural syndrome in a life history context, using a simple laboratory paradigm.     

Modelling the global heat balance

A previous model of the global heat balance has been expanded by including the influence of SO₂ pollution, water content of the atmosphere and cloudiness. It was found that the previous results were not changed significantly by this expansion of the model. The conclusions set up uising the previous model were still valid: (1) it is great importance to include the buffer capacity of the sea, including its dependence on pH and the temperature; (2) it is of importance to include natural climatic variations; (3) the dominanting factor is the trend in the consumption of fossil fuel.     

Occurrence of carbon monoxide during organic waste degradation

The concentrations of carbon monoxide (CO) and other gases were measured in the emissions from solid waste degradation under aerobic and anaerobic conditions during laboratory and field investigations. The emissions were measured as room temperature headspace gas concentrations in reactors of 1, 30, and 150 L, as well as sucked gas concentrations from windrow composting piles and a biocell, under field conditions. The aerobic composting laboratory experiments consisted of treatments with and without lime. The CO concentrations measured during anaerobic conditions varied from 0 to 3000 ppm, the average being 23 ppm, increasing to 133 ppm when methane (CH4) concentrations were low. The mean/maximum CO concentrations during the aerobic degradation in the 2-L reactor were 101/194 ppm without lime, 486/2022 ppm with lime, and 275/980 ppm in the 150-L reactors. The presence of CO during the aerobic composting followed a rapid decline in O2 concentrations Significantly higher CO concentrations were obtained when the aerobic degradation was amended with lime, probably because of a more extreme depletion of oxygen. The mean/maximum CO concentrations under field conditions during aerobic composting were 95/1000 ppm. The CO concentrations from the anaerobic biocell varied from 20 to 160 ppm. The hydrogen sulfide concentrations reached almost 1200 ppm during the anaerobic degradation and 67 ppm during the composting experiments.     

Oil and power industries’ responses to EU emissions trading: laggards or low-carbon leaders?

ABSTRACT

How have petroleum and power companies and their European industry associations responded to the EU emissions trading system (ETS)? Responses can be political, directed externally towards the initiation and reforms of the EU ETS itself, or internally and market-based, directed at low-carbon solutions. Proactive response strategies shape companies’ leadership potential. Variation in responses is explained by two models that differ in assumptions about corporate behaviour as well as the wider multilevel regulatory context in which companies operate. Responses are found to have converged within the two industries, with reactive companies following the proactive ones. Secondly, responses between the two industries increasingly diverge, with the power industry becoming much more proactive than the petroleum industry. The main explanation is found in the differing relevance of the two models and the wider regulatory context, particularly differing exposure to international competition and weak international climate agreements.     

Diel vertical migration and feeding patterns of Mysis mixta (Crustacea,Mysidacea) in the Baltic Sea

The extent of the nocturnal vertical migration of Mysis mixta Lilljeborg varied between early July and late October (of 1985 and 1986) in a coastal area of the Baltic Sea. Migration was more restricted in early July and late October. Seasonal changes in surface light levels and transparency were sufficient to explain the observed differences. Mysids avoided light levels above 10^-4 lux throughout the study period. Smaller juveniles migrated higher up than larger juveniles and adults. A two-layered distribution with part of the population close to the bottom was observed at night. Zooplankton were more abundant in water layers above the main concentration of mysids. M. mixta fed on phytoplankton, detritus, copepods, cladocerans, rotifers and tintinnids. Diel changes in gut fluorescence indicated a higher intake of phytoplankton at night, but levels were low compared to primarily herbivorous zooplankton. Comparisons of stomach contents of mysids caught at the bottom in the evening and in the water column at night showed a higher ingestion of zooplankton at night and of detritus during the day. Mysids caught at the bottom at night had an intermediate diet. Copepods and cladocerans constituted between 90 and 100% of ingested material by weight in all mysid groups.     

Reproduction of the commercial sea cucumber Holothuria whitmaei [Holothuroidea: Aspidochirotida] in the Indian and Pacific Ocean regions of Australia

Seasonal trends in the gonad index (GI) of two widely separated populations of black teatfish, Holothuria whitmaei (formerly included in Holothuria nobilis), were investigated between Pacific (Great Barrier Reef) and Indian Ocean (Ningaloo Reef) coral reefs of Australia. Reproductive activity followed a similar annual trend, with the GI of both populations peaking typically between April and June. Macroscopic and histological analysis of Ningaloo Reef specimens revealed that large germinal tubules, positioned centrally on the gonad basis, progressed through four maturity stages: growing (II); mature (III); partly spawned (IV); and spent (V). Growing tubules dominated the central region of the gonad basis between January and March, followed by an increase in the number of mature tubules throughout the GI peak (April–June). The progressive appearance of partly spawned and spent tubules between June and October suggests that spawning in H. whitmaei continues intermittently over an extended period throughout the austral winter. The examination of the gonad structure of sexually mature male and female specimens identified five tubule size classes in total (C₁ to C₅), each of differing physical and gametogenic status. In females, smaller C₁ tubules located at the anterior edge of the gonad basis contained pre- to early vitellogenic oocytes. Larger C₂ and C₃ tubule cohorts, positioned centrally on the gonad basis, contained mid- to late-stage vitellogenic oocytes. Smaller C₄ and C₅ tubules, located at the posterior edge, contained only relict oocytes. Similar physical and gametogenic differences were apparent between tubule cohorts in male specimens. We propose that these results, together with evidence of incomplete gonad resorption over the austral summer, indicate that gonad development in H. whitmaei conforms to the predictions of the Tubule Recruitment Model (TRM). The TRM is reported rarely among tropical aspidochirotes, and results presented here (1) provide the first direct evidence of this model in H. whitmaei, and (2) confirm that this species is one of the few winter-spawning tropical invertebrates.