Offspring genetic diversity increases fitness of female Atlantic salmon (Salmo salar)

Inbreeding has negative effects on individual and population performances. Therefore, enhancement of offspring genetic diversity is believed to play a major role in shaping mating systems. However, no study has clearly separated the direct effect of having multiple partners from the indirect effect of having more outbred offspring on the resulting reproductive success of individuals in the wild. In this study, we report significant associations between both multiple mating and within-individual genetic diversity of offspring, and an increased reproductive success of wild female Atlantic salmon, Salmo salar. Specifically, we found that females with a higher number of mates also have more outbred offspring (within-individuals), and that both of these characteristics increased their reproductive success expressed in terms of offspring surviving when combining all freshwater juvenile stages. Our findings also indicate that determinants of fitness are different among sexes as within-individual offspring genetic diversity was not a strong predictor of male reproductive success, while the number of mates was important. We also show that females mated with more outbred males than on average, which potentially increased their chances of producing outbred offspring. These results therefore suggest that there could be more important indirect genetic benefits of multiple mating for females than for males.Communicated by M. Abrahams     

Behavioral differences between Pogonomyrmex rugosus and dependent lineage (H1/H2) harvester ants

The discovery of genetic caste determination (GCD) in populations of Pogonomyrmex harvester ants raises many questions about the evolution and persistence of such populations. The genetic caste determination arises from the existence of two distinct, but mutually dependent, genetic lineages within a population. Workers always develop from a combination of the two lineages, but their sister queens develop from within-lineage matings. Maintaining genetic caste determination appears to be costly because many queen-destined eggs are wasted when a colony is not in the reproductive stage, yet these populations appear to be widespread. We investigated whether inter-lineage workers have novel traits that give GCD colonies a selective advantage in certain environments. In particular, we compared ecologically relevant behavioral characteristics of inter-lineage workers in H-lineage colonies with co-occurring normal colonies of P. rugosus. First, we measured colony defensive response toward a simulated vertebrate predator. Second, we set up direct competitive foraging and recruitment experiments between dependent lineage and P. rugosus colonies. Last, we measured individual aggressive response to foreign inter-lineage and P. rugosus workers. We found that H1/H2 inter-lineage workers explored objects on the nest more thoroughly and responded much more aggressively to simulated predator disturbance than the P. rugosus colonies. In individual encounters, H1/H2 inter-lineage and P. rugosus workers were equally aggressive toward foreign ants, but both worker types could discriminate P. rugosus from inter-lineage intruders and were more aggressive toward ants of the alternate type to themselves. When competing directly for resources, however, P. rugosus colonies consistently dominated seed piles. In summary, H1/H2 GCD colonies show distinct behavioral differences, but there is no clear ecological advantage from the traits we examined.     

Selenium content of rice,mixed plant foods and fish from Bangladesh

Static and dynamic adsorption studies of Co (II) ions have been undertaken at fixed pH and ionic strength taking binary biopolymeric beads of cross-linked calcium alginate and carboxy methylcellulose as biosorbents. The adsorption data were applied to Langmuir and Freundlich isotherm equations and various static parameters were calculated. The dynamic nature of adsorption process was quantified in terms of several kinetic constants such as rate constants for adsorption (K) and Lagergreen rate constant (K _ad). The influence of various experimental parameters such as solid-to-liquid ratio, pH, and temperature, the presence of salts and chemical composition of biopolymeric beads were investigated on the adsorption of cobalt ions.     

Some psychological consequences of striking: A six month,longitudinal study

The literature available on organizational psychology has largely neglected the issue of industrial conflict, and little is known about individual psychological effects of industrial conflict such as labour disputes and strikes. Psychological consequences of involvement in a strike were assessed in this research. Data were collected from 117 full-time, white collar union members immediately following a 22 day strike, and again two and six months later. Negatively perceived industrial relations events (e.g. 'strike or lockout', 'being involved in negotiations') were associated with marital adjustment, psychosomatic symptoms and a lack of psychological well-being on completion of the strike, and predicted unfavourable changes in psychological well-being over the next two and six months. A framework for understanding the negative effects of labour disputes and strikes is proposed, and the role of the organizational psychologist when such conflicts occur is considered.     

Reef size and isolation determine the temporal stability of coral reef fish populations

Temporal variance in species abundance, a potential driver of extinction, is linked to mean abundance through Taylor's power law, the empirical observation of a linear log-log relationship with a slope between 1 and 2 for most species. Here we test the idea that the slope of Taylor's power law can vary both among species and spatially as a function of habitat area and isolation. We used the world's most extensive database of coral reef fish communities comprising a 15-year series of fish abundances on 43 reefs of Australia's Great Barrier Reef. Greater temporal variances were observed at small and isolated reefs, and lower variances at large and connected ones. The combination of reef area and isolation was associated with an even greater effect on temporal variances, indicating strong empirical support for the idea that populations on small and isolated reefs will succumb more frequently to local extinction via higher temporal variability, resulting in lower resilience at the community level. Based on these relationships, we constructed a regional predictive map of the dynamic fragility of coral reef fish assemblages on the Great Barrier Reef.     

Flexible foraging movements of leatherback turtles across the North Atlantic Ocean

Some marine species have been shown to target foraging at particular hotspots of high prey abundance. However, we show here that in the year after a nesting season, female leatherback turtles (Dermochelys coriacea) in the Atlantic generally spend relatively little time in fixed hotspots, especially those with a surface signature revealed in satellite imagery, but rather tend to have a pattern of near continuous traveling. Associated with this traveling, distinct changes in dive behavior indicate that turtles constantly fine tune their foraging behavior and diel activity patterns in association with local conditions. Switches between nocturnal vs. diurnal activity are rare in the animal kingdom but may be essential for survival on a diet of gelatinous zooplankton where patches of high prey availability are rare. These results indicate that in their first year after nesting, leatherback turtles do not fit the general model of migration where responses to resources are suppressed during transit. However, their behavior may be different in their sabbatical years away from nesting beaches. Our results highlight the importance of whole-ocean fishing gear regulations to minimize turtle bycatch.