Social information facilitates learning about novel food sources in adult flower-visiting bats

Incorporating novel food sources into their diet is crucial for animals in changing environments. Although the utilization of novel food sources can be learned individually, learning socially from experienced conspecifics may facilitate this task and enable a transmission of foraging-related innovations across a population. In anthropogenically modified habitats, bats (Mammalia: Chiroptera) frequently adapt their feeding strategy to novel food sources, and corresponding social learning processes have been experimentally demonstrated in frugivorous and animalivorous species. However, comparable experiments are lacking for nectarivorous flower-visiting bats, even though their utilization of novel food sources in anthropogenically altered habitats is often observed and even discussed as the reason why bats are able to live in some areas. In the present study, we investigated whether adult flower-visiting bats may benefit from social information when learning about a novel food source. We conducted a demonstrator-observer dyad with wild Pallas' long-tongued bats (Glossophaga soricina; Phyllostomidae: Glossophaginae) and hypothesized that naïve individuals would learn to exploit a novel food source faster when accompanied by an experienced demonstrator bat. Our results support this hypothesis and demonstrate flower-visiting bats to be capable of using social information to expand their dietary repertoire.

Hypothalamic volume in pedophilia with or without child sexual offense

The hypothalamus regulates sexual behavior and is simultaneously associated with aggression and violence. Consequently, this brain region is relevant in research of pedophilia and child sexual offenses (CSO). The distinction between these two phenomena is of great importance and was the object of consideration of this study. We analyzed exclusively men, including 73 pedophilic offenders who committed CSO, an equal number of people with pedophilia but without such offenses, and 133 non-pedophilic, non-offending subjects who formed the control group. All data were collected in a multicenter in vivo study and analyzed using a semi-automated segmentation algorithm for 3-Tesla magnetic resonance images. Men with pedophilia who committed CSO on average had a 47 mm3 smaller hypothalamus per side than people without committed CSO. This effect was driven by both the group of non-offending people with pedophilia and the control group. By contrast, the exploratory comparison of pedophilic persons without CSO with the control group showed no significant difference. The present study demonstrates a deviant hypothalamic structure as a neurobiological correlate of CSO in pedophiles, but not in people with pedophilia who have not committed CSO. Thus, it strengthens the argument to distinguish between sexual offending and paraphilic sexual preferences.

The long-lasting impact of unemployment on life satisfaction: results of a longitudinal study over 20 years in East Germany

BACKGROUND

Economic disruption in East Germany at the time of reunification (1990) resulted in a noticeable increase in unemployment. The present study provides data from a German cohort for over 20 years. The aim was to examine how the frequency of experiencing unemployment affects life satisfaction and whether their relationship changes over time.

METHODS

In the Saxon Longitudinal Study, an age-homogeneous sample was surveyed annually from 1987 to 2016. Since 1996, 355 people (54% female) have been examined for issues related to unemployment. Life satisfaction was measured with both the Global Satisfaction with Life Scale and the Questions on Life SatisfactionModules questionnaire.

RESULTS

In 1996, the participants were 23 years old and 50% of the sample was affected by unemployment. At all 16 different measuring points, participants who were never unemployed indicated higher life satisfaction than those who were once unemployed. The repeatedly unemployed consistently reported the lowest values of life satisfaction. In each year, there were significant differences with small to medium effect sizes.

CONCLUSION

Our results support the notion that the adverse effects of unemployment on life satisfaction increase with the time spent unemployed. In 2016, only 2% of the cohort were currently unemployed, but differences between people with and without unemployment experience still exist. This indicates that the negative effect of the unemployment experience will last for a very long time. To the best of our knowledge, this is the first study that demonstrates the effect so persistently at so many measurement points for over 20 years.

Nitrate capture and slow release in biochar amended compost and soil

Slow release of nitrate by charred organic matter used as a soil amendment (i.e. biochar) was recently suggested as potential mechanism of nutrient delivery to plants which may explain some agronomic benefits of biochar. So far, isolated soil-aged and composted biochar particles were shown to release considerable amounts of nitrate only in extended (>1 h) extractions ("slow release"). In this study, we quantified nitrate and ammonium release by biochar-amended soil and compost during up to 167 h of repeated extractions in up to six consecutive steps to determine the effect of biochar on the overall mineral nitrogen retention. We used composts produced from mixed manures amended with three contrasting biochars prior to aerobic composting and a loamy soil that was amended with biochar three years prior to analysis and compared both to non-biochar amended controls. Composts were extracted with 2 M KCl at 22°C and 65°C, after sterilization, after treatment with H2O2, after removing biochar particles or without any modification. Soils were extracted with 2 M KCl at 22°C. Ammonium was continuously released during the extractions, independent of biochar amendment and is probably the result of abiotic ammonification. For the pure compost, nitrate extraction was complete after 1 h, while from biochar-amended composts, up to 30% of total nitrate extracted was only released during subsequent extraction steps. The loamy soil released 70% of its total nitrate amount in subsequent extractions, the biochar-amended soil 58%. However, biochar amendment doubled the amount of total extractable nitrate. Thus, biochar nitrate capture can be a relevant contribution to the overall nitrate retention in agroecosystems. Our results also indicate that the total nitrate amount in biochar amended soils and composts may frequently be underestimated. Furthermore, biochars could prevent nitrate loss from agroecosystems and may be developed into slow-release fertilizers to reduce global N fertilizer demands.