Search results for " Ni"
showing 10 items of 3074 documents
Niche partitioning amongst northwestern Mediterranean cetaceans using stable isotopes
2021
Abstract Ten species of cetaceans coexist in the Mediterranean Sea, one of the richest seas in biodiversity and endemisms worldwide. The conservation status of Mediterranean cetaceans has been a concern for many years, particularly due to increasing anthropogenic threats such as global warming and overfishing. We established the stable isotopic niches of carbon, nitrogen, and sulphur for five species of cetaceans inhabiting the northwestern Mediterranean Sea to elucidate the mechanisms of coexistence. The fin whale exploited epipelagic habitats with a low trophic level; the bottlenose dolphin was mostly neritic and had a high trophic level; the Risso’s dolphin was oceanic and fed bathypelag…
An invasive species, Carassius gibelio, alters the native fish community through trophic niche competition
2019
Carbon and nitrogen stable isotope analyses were used to determine isotopic niche width of the invasive fish species Carassius gibelio to help assess the niche overlap and potential impact of this species on the native fish fauna in the Karamenderes River, northwest Turkey. C. gibelio had the highest niche area of the coexisting species. The greatest overlap of isotopic niche was between C. gibelio and Mugil cephalus in the river mouth. The freshwater species displayed similar patterns when taking into consideration their relative abundance and isotopic overlap. While C. gibelio is likely to outcompete some species at some localities, the species was found co-occurring with others by maximu…
A Metabarcoding Survey on the Fungal Microbiota Associated to the Olive Fruit Fly.
2017
The occurrence of interaction between insects and fungi is interesting from an ecological point of view, particularly when these interactions involve insect pests and plant pathogens within an agroecosystem. In this study, we aimed to perform an accurate analysis on the fungal microbiota associated to Bactrocera oleae (Rossi) through a metabarcoding approach based on 454 pyrosequencing. From this analysis, we retrieved 43,549 reads that clustered into 128 operational taxonomic units (OTUs), of which 29 resulted in the “core” associate fungi of B. oleae. This fungal community was mainly represented by sooty mould fungi, such as Cladosporium spp., Alternaria spp. and Aureobasidium spp., by pl…
Quality Factors Influencing Consumer Demand for Small Fruit by Focus Group and Sensory Test
2017
ABSTRACTThe market of berries is a niche of high value in Italy. Small fruit’s healthy properties are well known in the international market, but little is known about the reason for a low commercialization rate of fresh small fruit in Italy. The objective of this study was to assess consumer preferences in Italy for selected berry species. Moreover, the study aims to identify the relevant attributes of berries that affect the demand for this produce according to consumers and to compare these attributes. We assessed relevant attributes affecting the demand for fresh berries for different consumers’ profiles and compared berries’ attributes rankings. The results reveal high concordance betw…
Sareomycetes: more diverse than meets the eye
2021
AbstractSince its resurrection, the resinicolous discomycete genus Sarea has been accepted as containing two species, one with black apothecia and pycnidia, and one with orange. We investigate this hypothesis using three ribosomal (nuITS, nuLSU, mtSSU) regions from and morphological examination of 70 specimens collected primarily in Europe and North America. The results of our analyses support separation of the traditional Sarea difformis s.lat. and Sarea resinae s.lat. into two distinct genera, Sarea and Zythia. Sarea as circumscribed is shown to conservatively comprise three phylospecies, with one corresponding to Sarea difformis s.str. and two, morphologically indistinguishable, correspo…
Parallel diversifications of Cremastosperma and mosannona (annonaceae), tropical rainforest trees tracking neogene upheaval of South America
2018
Much of the immense present day biological diversity of Neotropical rainforests originated from the Miocene onwards, a period of geological and ecological upheaval in South America. We assess the impact of the Andean orogeny, drainage of Lake Pebas and closure of the Panama isthmus on two clades of tropical trees ( Cremastosperma , ca 31 spp.; and Mosannona , ca 14 spp.; both Annonaceae). Phylogenetic inference revealed similar patterns of geographically restricted clades and molecular dating showed diversifications in the different areas occurred in parallel, with timing consistent with Andean vicariance and Central American geodispersal. Ecological niche modelling approaches show phyloge…
Understanding processes at the origin of species flocks with a focus on the marine Antarctic fauna
2017
Species flocks (SFs) fascinate evolutionary biologists who wonder whether such striking diversification can be driven by normal evolutionary processes. Multiple definitions of SFs have hindered the study of their origins. Previous studies identified a monophyletic taxon as a SF if it displays high speciosity in an area in which it is endemic (criterion 1), high ecological diversity among species (criterion 2), and if it dominates the habitat in terms of biomass (criterion 3); we used these criteria in our analyses. Our starting hypothesis is that normal evolutionary processes may provide a sufficient explanation for most SFs. We thus clearly separate each criterion and identify which biolog…
Origin and distribution of desert ants across the Gibraltar Straits
2017
The creation of geographic barriers has long been suspected to contribute to the formation of new species. We investigated the phylogeography of desert ants in the western Mediterranean basin in order to elucidate their mode of diversification. These insects which have a low dispersal capacity are recently becoming important model systems in evolutionary studies. We conducted an extensive sampling of species belonging to the Cataglyphis albicans group in the Iberian Peninsula (IP) and the northern Morocco (North Africa; NA). We then combined genetic, chemical and morphological analyses. The results suggest the existence of at least three and five clades in the IP and NA, respectively, whose…
Nitric oxide: a multitask player in plant–microorganism symbioses
2016
Symbiosis is a close and often long-term interaction between two different biological organisms, i.e. plants or fungi and microorganisms. Two main types of plant–microorganism interactions, mutualistic and cooperative, have been categorized. Mutualistic interactions, including nitrogen-fixing and mycorrhizal symbioses, refer to mostly obligate relationships between a host plant and a symbiont microorganism. Cooperative interactions correspond to less obligate and specific relationships. They involve microorganisms, referred to as plant growth-promoting rhizobia (PGPR), able to colonize root surface or inner tissues. Lichens are symbiotic associations of host fungi and photosynthetic partner…
Synthesis of Isomaltooligosaccharides by Saccharomyces cerevisiae Cells Expressing Aspergillus niger α‑Glucosidase
2017
The α-glucosidase encoded by the aglA gene of Aspergillus niger is a secreted enzyme belonging to family 31 of glycoside hydrolases. This enzyme has a retaining mechanism of action and displays transglycosylating activity that makes it amenable to be used for the synthesis of isomaltooligosaccharides (IMOs). We have expressed the aglA gene in Saccharomyces cerevisiae under control of a galactose-inducible promoter. Recombinant yeast cells expressing the aglA gene produced extracellular α-glucosidase activity about half of which appeared cell bound whereas the other half was released into the culture medium. With maltose as the substrate, panose is the main transglycosylation product after 8…