Lichens are symbiotic associations of fungi with microalgae and/or cyanobacteria, which are considered among the slowest growing organisms, with strong tolerance to adverse environmental conditions. ...There are about 400 genera and 1600 species of lichens and those belonging to the
genus comprise about 360 of these species.
lichens have been used since ancient times as dyes, cosmetics, preservatives, deodorants and folk medicines. The phytochemistry of the
genus includes more than 60 compounds which belong to the following classes: depsides, depsidones, depsones, lactones, quinones, phenolics, polysaccharides, fatty acids and dibenzofurans. Due to scarce knowledge of metabolomic profiles of
species (
,
,
and
), a study based on UHPLC-ESI-OT-MS-MS was performed for a comprehensive characterization of their secondary metabolites. From the methanolic extracts of these species a total of 73 metabolites were identified for the first time using this hyphenated technique, including 34 compounds in
, 21 in
, 38 in
and 37 in
. Besides, a total of 13 metabolites were not identified and reported so far, and could be new according to our data analysis. This study showed that this hyphenated technique is rapid, effective and accurate for phytochemical identification of lichen metabolites and the data collected could be useful for chemotaxonomic studies.
Monogamy appears to have become the predominant human mating system with the emergence of highly unequal agricultural populations that replaced relatively egalitarian horticultural populations, ...challenging the conventional idea—based on the polygyny threshold model—that polygyny should be positively associated with wealth inequality. To address this polygyny paradox, we generalize the standard polygyny threshold model to a mutual mate choice model predicting the fraction of women married polygynously. We then demonstrate two conditions that are jointly sufficient to make monogamy the predominant marriage form, even in highly unequal societies. We assess if these conditions are satisfied using individual-level data from 29 human populations. Our analysis shows that with the shift to stratified agricultural economies: (i) the population frequency of relatively poor individuals increased, increasing wealth inequality, but decreasing the frequency of individuals with sufficient wealth to secure polygynous marriage, and (ii) diminishing marginal fitness returns to additional wives prevent extremely wealthy men from obtaining as many wives as their relative wealth would otherwise predict. These conditions jointly lead to a high population-level frequency of monogamy.
While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested ...whether subsistence activities-incorporating market integration-are associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as "farmers" did not have higher fertility than others, while "foragers" did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence.
Documenting larval behavior is critical for building an understanding of larval dispersal dynamics and resultant population connectivity. Nocturnal diel vertical migration (DVM), a daily migration ...towards the surface of the water column at night and downward during the day, can profoundly influence dispersal outcomes. Via laboratory experiments we investigated whether marine gastropod Kelletia kelletii larvae undergo nocturnal DVM and whether the behavior was influenced by the presence of light, ontogeny, and laboratory culturing column height. Larvae exhibited a daily migration pattern consistent with nocturnal diel vertical migration with lower average vertical positioning (ZCM) during day-time hours and higher vertical positioning at night-time hours. ZCM patterns varied throughout ontogeny; larvae became more demersal as they approached competency. There was no effect of column height on larval ZCM. DVM behavior persisted in the absence of light, indicating a possible endogenous rhythm. Findings from field plankton tows corroborated laboratory nocturnal DVM findings; significantly more K. kelletii were found in surface waters at midnight compared to at noon. Unraveling the timing of and the cues initiating DVM behavior in K. kelletii larvae can help build predictive models of dispersal outcomes for this emerging fishery species.
Small-scale non-industrialized farmers using traditional ecological knowledge (TEK) and household labor manage a system of shifting cultivation in their maize milpa and matahambre forest plots. The ...feedbacks from their immediate environment and household provide a platform where micro-level agricultural dynamics are practiced for subsistence. In Belize, Mayan farmers in their lands sustain their families and maintain a level of sustainability by relying on their household, ecology, and community rather than industrialized or mechanized strategies. This dissertation details three main facets of this farming system: 1.) The effect of fallow and soil property on maize yields in a shifting swidden farm system called the milpa, 2.) The effect of household (HH) labor and cultivation lengthing on the selection of weed control strategies in the slash and mulch farm type, matahambre and 3.) The effect of school enrollment has on how much school going versus non-school going young adults participate in activities that build traditional ecological knowledge (TEK). We did not find an effect of fallow length, or any of our soil properties (pH, TKN, %OM, or P) on maize yields. This suggests that other cultural factors such as land tenure, weeding management, and pest management may instead play a role in the selection of sites with a variety of fallow ages for planting maize. In the matahambre system we find that household hand weeding is still the prevalent method of weeding and weakly found support for the relationship of cultivation lengthening associated with a decrease in the use of herbicides while displaying an increase in the use of both herbicides and cover crops. Finally, critical to land-based subsistence activities, is TEK that is learned by young adults by participating in community agro-ecological activities that engage the practice of this knowledge. We find no difference between school going (SG) and non-school going (NSG) females’ time devoted to TEK related activities. We also found that SG males spend less time engaged in agricultural related activities than NSG males. Despite the national state level policies that attempt to undermine land tenure, customary management of milpa and matahambre farming, and threaten traditional ecological learning in the Mayan lands, Mayan farmers’ milpa management with respect to fallow does not appear to hinder their sustainability in terms of yields and possibly to soil. Management of matahambre continues to consider HH weeding as its main method of weeding rather than the use of herbicides or cover crops. Finally, our final results suggest that traditional ecological knowledge and agricultural activities must be included in school curriculum to transmit subsistence farming knowledge. Altering farming practices without full consideration of HH decision making, the parameters these decisions are made under, their consequences on the environment and the exclusion of the farmer’s themselves from the development project table is detrimental to long term sustainability of both natural and human communities.
Distribution shift is a common situation in machine learning tasks, where the data used for training a model is different from the data the model is applied to in the real world. This issue arises ...across multiple technical settings: from standard prediction tasks, to time-series forecasting, and to more recent applications of large language models (LLMs). This mismatch can lead to performance reductions, and can be related to a multiplicity of factors: sampling issues and non-representative data, changes in the environment or policies, or the emergence of previously unseen scenarios. This brief focuses on the definition and detection of distribution shifts in educational settings. We focus on standard prediction problems, where the task is to learn a model that takes in a series of input (predictors) \(X=(x_1,x_2,...,x_m)\) and produces an output \(Y=f(X)\).
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