Contrasting time-scale effects of land-use legacy on species richness,diversity and composition in Mediterranean scrubland communities

Context

It is known that land-use and land-cover (LULC) changes affect plant community assembly for decades. However, both the short- and the long-term effects of contrasting LULC change pathways on this assembly are seldom explored.

Objectives

To assess how LULC change pathways affect woody plant community parameters (i.e. species richness, diversity and evenness) and species’ presence and abundance, compared with environmental factors and neutral processes.

Methods

The study was performed in Mediterranean limestone scrublands in NE Spain. Cover of each woody species was recorded in 150 scrubland plots belonging to five LULC change pathways along the past century, identified using land-cover maps and fieldwork. For each plot, total woody and herbaceous vegetation cover, local environmental variables and geographical position were recorded. Effects of these pathways and factors on plant community parameters and on species presence and abundance were assessed, considering spatial effects potentially associated to neutral processes.

Results

Species richness and diversity were associated with LULC change pathways and elevation, while evenness was only associated with this last. Pathways and environmental variables explained similar variance in both species’ presence and cover. In general, while community parameters were affected by recent-past (1956) use, species presence and abundance were associated with far-past (pre-1900) cropping. No relevant spatial effect was detected for any studied factor.

Conclusions

Historical LULC changes and current environmental factors drive local-scale community assembly in Mediterranean scrublands to an equal extent, while contrasting time-scale effects are found at community and species level. Neutral, dispersal-based processes are found to be non-relevant.

     

The suppressive effects of composts used as growth media against <Emphasis Type="Italic">Botrytis cinerea</Emphasis> in cucumber plants

The incidence/severity of soil-borne plant diseases is often reduced when composts are used as growth media. However, much less information is available about the effects of composts on the development of foliar diseases. Here we studied the suppressive capacity of five composts (from olive marc-cotton gin trash, grape marc, cork, spent mushroom and municipal organic and yard wastes) as growth media against Botrytis cinerea disease in cucumber plants. We also examined the putative correlations of several biotic and abiotic factors involved in disease suppression. The suppressive capacity of the growth media was studied by comparing disease incidence/severity in plants grown in composts with that occurring in plants grown in commercial peats, which are conducive to most soilborne diseases. Correlations were made between the occurrence of disease and leaf nutrient status, as well as electrical conductivity (EC) and microbial activity (measured as β-glucosidase activity) in the growth media. Cucumber plants grown in the peats showed greater severity of B. cinerea during the bioassay than those grown in composts. Mo, Ca and Si content in leaves showed negative correlations with this disease. A negative correlation with disease severity was observed for EC and microbial activity in the growth media. The noticeable reduction in B. cinerea in plants grown in composts was related to the supply of specific chemical elements, a certain degree of salt stress, and the high microbial activity of composts.     

Epistatic interactions between pterin and carotenoid genes modulate intra-morph color variation in a lizard

Color polymorphisms have become a major topic in evolutionary biology and substantial efforts have been devoted to the understanding of the mechanisms responsible for originating such colorful systems. Within-morph continuous variation, on the other hand, has been neglected in most of the studies. Here, we combine spectrophotometric/visual modeling and genetic data to study the mechanisms promoting continuous variation within categorical color morphs of Podarcis muralis. Our results suggest that intra-morph variability in the pterin-based orange morph is greater compared to white and yellow morphs. We also show that continuous variation within the orange morph is partially discriminable by conspecifics. Genotyping results indicate that allelic variants at the BCO2 locus (responsible for deposition of yellow carotenoids) contribute to generate continuous variation in orange individuals. However, other intrinsic and/or extrinsic mechanisms, such as body size, might be involved, opening a new avenue for future research on the drivers of continuous variation within-morphs.     

A magnetized jet from a massive protostar

Synchrotron emission is commonly found in relativistic jets from active galactic nuclei (AGNs) and microquasars, but so far its presence in jets from young stellar objects (YSOs) has not been proved. Here, we present evidence of polarized synchrotron emission arising from the jet of a YSO. The apparent magnetic field, with strength of ~0.2 milligauss, is parallel to the jet axis, and the polarization degree increases toward the jet edges, as expected for a confining helical magnetic field configuration. These characteristics are similar to those found in AGN jets, hinting at a common origin of all astrophysical jets.     

The larger,the better? Effects of delayed diameter-limit cutting on old-growth attributes and saproxylic beetle diversity in temperate oak forests

Intensive management implies harvesting large, old trees, which reduces the old-growth attributes. This negatively affects biodiversity, especially saproxylic beetles. In managed temperate oak forests, rotation extension induced by increasing the diameter threshold of final harvest by about 10 cm compared to conventional practices (i.e. DBH around 70 cm) might mitigate this negative effect. Here, we used a gradient of the proportion of overmature trees (DBH?≥?80 cm) among mature trees (DBH?≥?70 cm) across plots of high oak French forests to test the potential effect of increasing diameter threshold on (1) structural features and (2) species composition and diversity of saproxylic beetles communities. We assessed deadwood and microhabitats availability (i.e. volume/density and diversity) and canopy openness in 81 1-ha plots across eleven French forests. Results highlighted that a larger proportion of overmature trees, for a given density of mature trees, had limited effects on structural features: only cavities density showed a significant positive response, with no cascading effect on cavicolous beetles. Moreover, the proportion of overmature trees had no significant effect on the composition of saproxylic beetles communities (and ecological variables altogether explained only 17% of the composition inertia). By contrast, mature tree density enhanced microhabitat density and indirectly increased the abundance of rare species. Thus, shifting DBH from 70 to 80 cm in high oak forest could have no or limited effect on saproxylic beetles conservation. Improved strategies might rather stem from combining (1) longer rotation extension and (2) less intensive management practices in extended rotation stands.     

Nicotinic acetylcholine receptor β2 subunits in the medial prefrontal cortex control attention

More than one-third of all people are estimated to experience mild to severe cognitive impairment as they age. Acetylcholine (ACh) levels in the brain diminish with aging, and nicotinic ACh receptor (nAChR) stimulation is known to enhance cognitive performance. The prefrontal cortex (PFC) is involved in a range of cognitive functions and is thought to mediate attentional focus. We found that mice carrying nAChR β2-subunit deletions have impaired attention performance. Efficient lentiviral vector-mediated reexpression of functional β2-subunit-containing nAChRs in PFC neurons of the prelimbic area (PrL) completely restored the attentional deficit but did not affect impulsive and motivational behavior. Our findings show that β2-subunit expression in the PrL PFC is sufficient for endogenous nAChR-mediated cholinergic regulation of attentional performance.     

Earlier migration and distribution changes of albacore in the Northeast Atlantic

Marine species have exhibited trends in their geographic distribution and phenology in recent decades, and these changes are triggered by climate variability or anthropogenic pressures. Northeast Atlantic albacore has recently been identified to show changes of this nature, although the underlying causes are still uncertain. The aim of this work was to analyse the Northeast Atlantic albacore distribution shifts and phenological changes during the trophic migration that juveniles undertake from late spring to autumn and to identify potential causes of such variability. Specifically, time series of albacore catches of the Basque trolling fleet were studied and compared with trends derived from a null ecological niche model using very large number of catch observations (27,982). The results showed an earlier albacore migration of 2.3 days per decade during the period of 1981–2017, which was partly associated with the recent warming of the sea. The trend analysis of the catch distribution also detected a significant north‐westward trend in catch observations and a northward trend in species habitat. In contrast, both latitudinal trends were uncorrelated. This result suggests that interannual species distribution shifts are mainly related to factors other than oceanic‐climatic variability, such as fleet behaviour or prey changes.     

ESBL- and plasmidic class C beta-lactamase-producing E. coli strains isolated from poultry, pig and rabbit farms

This study aims to determine the presence of extended-spectrum (ESBL) and plasmidic class C beta-lactamase-producing Enterobacteriaceae in poultry, pig and rabbit farms of Catalonia (Spain). PFGE typing showed a low clonal relationship among strains carrying these mechanisms of resistance. Ninety-three percent of them were resistant to two or more of the non-beta-lactam antimicrobials tested and harboured ESBL and plasmidic class C beta-lactamases. Greater diversity of these enzymes was found in strains from poultry farms, the CTX-M-9 family, especially CTX-M-14, with CMY-2 being the most frequent. The isolation of TEM-52 and SHV-2-producing Escherichia coli strains from these animal farms is noteworthy. In contrast, 73% of the strains from pig farms had CTX-M-1, and neither the CMY-type nor CTX-M-9 family enzyme was found. Likewise, it is the first time that CTX-M-1 and SHV-5 encoding strains have been isolated in pigs. On the other hand, in rabbit farms CTX-M-9 family was also the most frequent, being detected in three of a total of four strains. The last one showed a CMY-2, for the first time detected in these animals, too. In conclusion, commensal E. coli strains of food-producing animal farms are a reservoir of ESBL and plasmidic class C beta-lactamases.