Larger brain size indirectly increases vulnerability to extinction in mammals

Although previous studies have addressed the question of why large brains evolved, we have limited understanding of potential beneficial or detrimental effects of enlarged brain size in the face of current threats. Using novel phylogenetic path analysis, we evaluated how brain size directly and indirectly, via its effects on life history and ecology, influences vulnerability to extinction across 474 mammalian species. We found that larger brains, controlling for body size, indirectly increase vulnerability to extinction by extending the gestation period, increasing weaning age, and limiting litter sizes. However, we found no evidence of direct, beneficial, or detrimental effects of brain size on vulnerability to extinction, even when we explicitly considered the different types of threats that lead to vulnerability. Order‐specific analyses revealed qualitatively similar patterns for Carnivora and Artiodactyla. Interestingly, for Primates, we found that larger brain size was directly (and indirectly) associated with increased vulnerability to extinction. Our results indicate that under current conditions, the constraints on life history imposed by large brains outweigh the potential benefits, undermining the resilience of the studied mammals. Contrary to the selective forces that have favored increased brain size throughout evolutionary history, at present, larger brains have become a burden for mammals.     

Restoration of grazing management and its effect on vegetation in an upland grassland

Question: How are plant species and functional group composition, and potential sward height affected by implementation of different grazing regimes on previously abandoned semi-natural grassland? Location: The Jizerské mountains, northern Czech Republic. Methods: We established a randomized block experiment with the following treatments: unmanaged control (U), intensive (IG) and extensive (EG) continuous grazing, first cut followed by intensive (ICG) and first cut followed by extensive (ECG) continuous grazing for the rest of the growing season. The percentage cover of all vascular plant species was recorded in 40 permanent plots. Results: Total plant species richness increased in all managed treatments, whereas species number was reduced in U at the end of the experiment. Tall forbs (Aegopodium podagraria, Galium album, Anthriscus sylvestris, Cirsium arvense) as well as tall grasses (Elytrigia repens and Alopecurus pratensis) were more abundant in U. Species associated with both grazing treatments (IG, EG) were Dactylis glomerata, Festuca rubra agg. and Phleum pratense. Agrostis capillaris, Taraxacum spp., Trifolium repens, Ranunculus repens and Cirsium vulgare were promoted by ECG and ICG. Abundance of tall grasses and tall forbs reflected the intensity of management in the order U>EG, ECG>IG, ICG. Prostrate forbs, on the other hand, increased their cover with increasing intensity: ICG>IG>ECG>EG. Conclusions: Plant species composition of semi-natural grasslands is affected by the defoliation regime. Continuous grazing on abandoned grassland alters the sward structure towards a permanent pasture with short, light-sensitive grasses and prostrate forbs. To maintain or enhance plant species richness in semi-natural grasslands, understanding the effects of different grazing regimes on plant species composition is necessary.     

Species richness and wood production: a positive association in Mediterranean forests

A major debate in the study of biodiversity concerns its influence on ecosystem functioning. We compared whether wood production in forests was associated with tree functional group identity (i.e. deciduous, conifer or sclerophylous), tree species richness (1–≥ 5) and tree functional group richness (1–3) by comparing more than 5000 permanent plots distributed across Catalonia (NE Spain). Deciduous forests were more productive than coniferous and sclerophylous forests. Wood production increased with tree species richness. However, functional group richness increased wood production only in sclerophylous forests. When other forest structure, environmental variables and management practices were included in the analysis, tree functional group identity and species richness still remained significant, while functional species richness did not. Our survey indicates that across a regional scale, and across a broad range of environmental conditions, a significant positive association exists between local tree species richness and wood production at least in typical early successional Mediterranean-type forests.     

Contrasting plant physiological adaptation to climate in the native and introduced range of Hypericum perforatum

How introduced plants, which may be locally adapted to specific climatic conditions in their native range, cope with the new abiotic conditions that they encounter as exotics is not well understood. In particular, it is unclear what role plasticity versus adaptive evolution plays in enabling exotics to persist under new environmental circumstances in the introduced range. We determined the extent to which native and introduced populations of St. John's Wort (Hypericum perforatum) are genetically differentiated with respect to leaf-level morphological and physiological traits that allow plants to tolerate different climatic conditions. In common gardens in Washington and Spain, and in a greenhouse, we examined clinal variation in percent leaf nitrogen and carbon, leaf delta(13)C values (as an integrative measure of water use efficiency), specific leaf area (SLA), root and shoot biomass, root/shoot ratio, total leaf area, and leaf area ratio (LAR). As well, we determined whether native European H. perforatum experienced directional selection on leaf-level traits in the introduced range and we compared, across gardens, levels of plasticity in these traits. In field gardens in both Washington and Spain, native populations formed latitudinal clines in percent leaf N. In the greenhouse, native populations formed latitudinal clines in root and shoot biomass and total leaf area, and in the Washington garden only, native populations also exhibited latitudinal clines in percent leaf C and leaf delta(13)C. Traits that failed to show consistent latitudinal clines instead exhibited significant phenotypic plasticity. Introduced St. John's Wort populations also formed significant or marginally significant latitudinal clines in percent leaf N in Washington and Spain, percent leaf C in Washington, and in root biomass and total leaf area in the greenhouse. In the Washington common garden, there was strong directional selection among European populations for higher percent leaf N and leaf delta(13)C, but no selection on any other measured trait. The presence of convergent, genetically based latitudinal clines between native and introduced H. perforatum, together with previously published molecular data, suggest that native and exotic genotypes have independently adapted to a broad-scale variation in climate that varies with latitude.     

In situ bioremediation using biosurfactant produced by solid state fermentation

The discovery that certain microorganisms, living within a marine environment, can actually degrade components of oil, has made possible the utilization of biological methods for the treatment of oil spills. A biosurfactant accelerates the process of degradation of pollutant composites. The objective of this work was to study the bioremediation in situ of a diesel oil spill by utilizing a biosurfactant produced through fermentation and then compare it with chemical remediation. The quantification and identification of hydrocarbons were carried out by the process of gas chromatography. The soil indigenous microorganisms were monitored. The experiment with biosurfactant reached reductions of 99% of the aliphatic hydrocarbons, while that of the chemical disperser experiment reached a maximum of 90% reduction in 180 days. In 15 days the biosurfactant removed 77% of the aliphatic hydrocarbons, the diesel oil experiment 8.7% and the chemical disperser only 5%. The biosurfactant was 99% effective for the removal of aromatic polycyclic hydrocarbons, up to 3 rings.     

Production of <Emphasis Type="Italic">Chlorella</Emphasis> biomass enriched by selenium and its use in animal nutrition: a review

Feedstuffs are routinely supplemented with various selenium sources, where organic forms of Se are more bio-available and less toxic than the inorganic forms (selenites, selenates). When the algae are exposed to environmental Se in the form of selenite, they are able as other microorganisms to incorporate the element to different levels, depending on the algae species. Technology of heterotrophic fed-batch cultivation of the microalga Chlorella enriched by organically bound Se was developed, where the cultivation proceeds in fermentors on aerated and mixed nutrient solution with urea as a nitrogen and glucose as a carbon and energy source. High volumetric productivity and high cell concentrations (about 70–100 g Chlorella dry mass l⁻¹) can be attained if nutrients and oxygen are adequately supplied. Addition of a small quantity of a new selenoprotein source-spray-dried Se-Chlorella biomass to the diet of farm animals had better effects on specific physiological and physical parameters of animals than selenite salt and was comparable with Se yeast added to the diet. This review introduces the importance of selenium for humans and animals, methods of Se determination, heterotrophic production of selenium-enriched Chlorella biomass in a fed-batch culture regime on organic carbon, and use of the biomass in animal nutrition.     

Effects of Rosmarinus officinalis neighbors on resprouting of Erica multiflora individuals

To study the effects of competition in Mediterranean shrubland regeneration following disturbance, we used a neighborhood approach to assess the influence of mature Rosmarinus officinalis neighbors on the resprouting of Erica multiflora individuals after clipping. Sprout biomass of target plants 2 years after clipping was regressed against various measures of neighbor abundance within a 2 m radius around target E. multiflora individuals in which all vegetation except R. officinalis had been removed. The largest single influence on the biomass of sprouts produced was the previous biomass of the resprouting plant. The abundance of R. officinalis neighbors had a weak but detectable effect on resprouting of E. multiflora. Abundance of neighbors within 60 cm from target plants was the best predictor of regrowth. At this distance, two simple measures of neighbor abundance within the neighborhood, the number of neighbors and the sum of their heights, were significant in accounting for variation in resprouted biomass. None of the combinations of neighbor variables performed significantly better than single variables. The best models accounted for around 24 percent of the variation in resprout biomass. As in other studies, angular dispersion of neighbors never had a significant effect on performance of target plants. The weak but significant response of resprouting to variation in R. officinalis abundance suggests that the intensity of competition in the experiment was low because of the removal of other species.     

Phylogeographical analyses of domestic and wild yaks based on mitochondrial DNA: new data and reappraisal

Aim We aimed to examine the phylogeographical structure and demographic history of domestic and wild yaks (Bos grunniens) based on a wide range of samples and complete mitochondrial genomic sequences. Location The Qinghai‐Tibetan Plateau (QTP) of western China. Methods All available D‐loop sequences for 405 domesticated yaks and 47 wild yaks were examined, including new sequences from 96 domestic and 34 wild yaks. We further sequenced the complete mitochondrial genomes of 48 domesticated and 21 wild yaks. Phylogeographical analyses were performed using the mitochondrial D‐loop and the total genome datasets. Results We recovered a total of 123 haplotypes based on the D‐loop sequences in wild and domestic yaks. Phylogenetic analyses of this dataset and the mitochondrial genome data suggested three well‐supported and divergent lineages. Two lineages with six D‐loop haplogroups were recovered for all morphological breeds of domestic yaks across their distributions in the QTP, while one more lineage and more endemic haplogroups or haplotypes were found for wild yaks. Based on the mitochondrial genome data, the divergences of the three lineages were estimated to have occurred around 420,000 and 580,000 years ago, consistent with the geological records of two large glaciation events experienced in the QTP. Main conclusions There are distinct phylogeographical differences between wild and domestic yaks. However, there is no apparent geographical correlation between identified haplogroups and distributions of domestic yaks. Three differentiated lineages of yaks probably evolved allopatrically in different regions during the Pleistocene glaciation events, then reunited into a single gene pool during post‐glacial population expansion and migrations before the start of the domestication of yaks in the Holocene.     

The administration of oleoyl-estrone to lactating dams induces selective changes in the normal growth pattern of their pups.

To determine the effects of oleoyl-estrone treatment on the lactating dams and on the growth pattern of developing rats, female Wistar rats were randomly divided into two groups after delivery. One group received a daily gavage of 0.2 mL sunflower oil containing 10 micromol oleoyl-estrone/kg (treated group) and the other received a daily intragastric gavage of 0.2 mL sunflower oil (control group). Treatment was carried out during the first 15 days of lactation. Dams were killed on days 1, 15 or 20 after delivery and pups were sacrificed on days 1, 15, 20 or 30. Treated dams showed a transient decrease in food intake, significant lower lipid content than control dams, with a parallel maintenance of protein content and no appreciative changes in plasmatic parameters. However, a significant increase in brown adipose tissue mass was detected in treated group. Pups from treated dams showed a decrease in their growth rate that was reflected in the lower adipose tissue mass in different locations, except in the case of brown adipose tissue and, that continued after cessation of treatment. Thus, treatment affects dams in a selective way that does not coincide with a simple food restriction model.     

Contrasting effects of invasive plants in plant–pollinator networks

The structural organization of mutualism networks, typified by interspecific positive interactions, is important to maintain community diversity. However, there is little information available about the effect of introduced species on the structure of such networks. We compared uninvaded and invaded ecological communities, to examine how two species of invasive plants with large and showy flowers (Carpobrotus affine acinaciformis and Opuntia stricta) affect the structure of Mediterranean plant–pollinator networks. To attribute differences in pollination to the direct presence of the invasive species, areas were surveyed that contained similar native plant species cover, diversity and floral composition, with or without the invaders. Both invasive plant species received significantly more pollinator visits than any native species and invaders interacted strongly with pollinators. Overall, the pollinator community richness was similar in invaded and uninvaded plots, and only a few generalist pollinators visited invasive species exclusively. Invasive plants acted as pollination super generalists. The two species studied were visited by 43% and 31% of the total insect taxa in the community, respectively, suggesting they play a central role in the plant–pollinator networks. Carpobrotus and Opuntia had contrasting effects on pollinator visitation rates to native plants: Carpobrotus facilitated the visit of pollinators to native species, whereas Opuntia competed for pollinators with native species, increasing the nestedness of the plant–pollinator network. These results indicate that the introduction of a new species to a community can have important consequences for the structure of the plant–pollinator network.