Search results for " space"
showing 10 items of 4562 documents
Sex in space: population dynamic consequences
1999
Sex, so important in the reproduction of bigametic species, is nonetheless often ignored in explorations of the dynamics of populations. Using a growth model of dispersal-coupled populations we can keep track of fluctuations in numbers of females and males. The sexes may differ from each other in their ability to disperse and their sensitivity to population density. As a further complication, the breeding system is either monogamous or polygamous. We use the harmonic mean birth function to account for sex-ratio-dependent population growth in a Moran–Ricker population renewal process. Incorporating the spatial dimension stabilizes the dynamics of populations with monogamy as the breeding sys…
Pleurotus opuntiae revisited e An insight to the phylogeny of dimitic Pleurotus species with emphasis on the P. djamor complex
2018
Abstract The name Pleurotus opuntiae is indiscriminately used for describing mushrooms with white to off-white to white-grey pilei with short or absent stipe and dimitic hyphal system, which grow on plants of the genera Opuntia, Yucca, Agave, Phytolacca etc. However, the outcome of the present study evidences that this name should be reserved for specimens deriving from the Mediterranean area only; an epitype originating from Italy on Opuntia ficus-indica is designated. Pertinent material was sequenced by using the internal transcribed spacer region (ITS) and found to be phylogenetically related to P. djamor from Kenya and Nigeria, while members of the P. djamor complex from other continent…
Developing an orientation and cutting point determination algorithm for a trout fish processing system using machine vision
2019
Abstract Fish processing in small and medium fish supplying centers requires an intelligent system to operate on different sizes. Therefore, an image processing algorithm was developed to extract the proper head and belly cutting points according to the trout dimensions. The algorithm detects the fish orientation and location of pectoral, anal, pelvic, and caudal fins. In this study, each of the trout images was divided into slices along its length in order to segment the fins and extract cutting points. The channel ‘B’ of RGB color space was considered in both initial segmentation and fin detection stages among the examined channels of RGB, HSV, and L*a*b* color spaces. The back-belly and …
Checklist of gypsophilous vascular flora in Italy
2018
Our understanding of the richness and uniqueness of the flora growing on gypsum substrates in Italy has grown significantly since the 19th century and, even today, new plant species are still being discovered. However, the plants and plant communities, growing on gypsum substrates in Italy, are still a relatively unknown subject. The main aim of this paper was to elaborate a checklist of the Italian gypsophilous flora, to increase knowledge about this peculiar flora and for which conservation efforts need to be addressed. Through a structured group communication process of experts (application of the Delphi technique), a remarkable number of experienced Italian botanists have joined togethe…
No exception to the rule: Candidatus Portiera aleyrodidarum cell wall revisited
2014
International audience; Many insect endosymbionts described so far are gram-negative bacteria. Primary endosymbionts are obligatory bacteria usually harboured by insects inside vacuoles in specialized cells called bacteriocytes. This combination produces a typical three-membrane system with one membrane derived from the insect vacuole and the other two from the bacterial gram-negative cell envelope, composed by the cell wall (the outer membrane plus the periplasmic space) and the plasma membrane (the inner membrane). For the last 21 years, the primary endosymbiont of whiteflies 'Candidatus Portiera aleyrodidarum' was considered an exception to this rule. Previous works stated that only two …
Ecology, Phylogeny, and Potential Nutritional and Medicinal Value of a Rare White “Maitake” Collected in a Mediterranean Forest
2020
Albino Grifola frondosa (Dicks.) Gray &ldquo
Assessing cetacean surveys throughout the Mediterranean Sea: a gap analysis in environmental space
2018
Heterogeneous data collection in the marine environment has led to large gaps in our knowledge of marine species distributions. To fill these gaps, models calibrated on existing data may be used to predict species distributions in unsampled areas, given that available data are sufficiently representative. Our objective was to evaluate the feasibility of mapping cetacean densities across the entire Mediterranean Sea using models calibrated on available survey data and various environmental covariates. We aggregated 302,481 km of line transect survey effort conducted in the Mediterranean Sea within the past 20 years by many organisations. Survey coverage was highly heterogeneous geographicall…
Phylogenetic relationships among tetraploid species of Bellevalia (Asparagaceae) endemic to south-central Mediterranean
2017
AbstractIn the south-central Mediterranean four tetraploid species of Bellevalia occur: B. dolichophylla, B. galitensis, B. mauritanica, and B. pelagica. Another group of plants, morphologically similar to B. dolichophylla, has been recently recovered in Zembra Island (Tunisia). A phylogenetic reconstruction involving all these tetraploid taxa was performed using both plastidial and nuclear markers (trnL-trnF and ITS, respectively). For all these taxa, an allopolyploid origin involving B. romana and B. dubia is supported. Regarding plants from Zembra, they may fall within the variability of B. dolichophylla.
Bot gummosis of lemon (Citrus × limon) caused by neofusicoccum parvum
2021
Neofusicoccum parvum, in the family Botryosphaeriaceae, was identified as the causal agent of bot gummosis of lemon (Citrus × limon) trees, in the two major lemon-producing regions in Italy. Gummy cankers on trunk and scaffold branches of mature trees were the most typical disease symptoms. Neofusicoccum parvum was the sole fungus constantly and consistently isolated from the canker bark of symptomatic lemon trees. It was identified on the basis of morphological characters and the phylogenetic analysis of three loci, i.e., the internal transcribed spacer of nuclear ribosomal DNA (ITS) as well as the translation elongation factor 1-alpha (TEF1) and β-tubulin (TUB2) genes. The pathogenicity o…
Analysis of trematode parasite communities in fish eye lenses by pyrosequencing of naturally pooled DNA.
2011
Infections by multiple parasite species are common in nature and have important consequences for between species interactions and coevolutionary dynamics with the host populations. For example ecological and evolutionary factors underlying the structure of parasite communities determine the range of hosts a parasite can infect and set the basis for both evolution of host defences and parasite virulence as well as management of diseases. Studies investigating these factors have been facilitated in the recent past by genetic methods which surmount difficulties of traditional morphological taxonomy in identifying individual parasite species. Here we take a step further and present a novel meth…