Search results for "Idea"
showing 10 items of 1268 documents
An Algebraic Derivation of Chao’s Estimator of the Number of Species in a Community Highlights the Condition Allowing Chao to Deliver Centered Estima…
2014
Anne Chao proposed a very popular, nonparametric estimator of the species richness of a community, on the basis of a limited size sampling of this community. This expression was originally derived on a statistical basis as a lower-bound estimate of the number of missing species in the sample and provides accordingly a minimal threshold for the estimation of the total species richness of the community. Hereafter, we propose an alternative, algebraic derivation of Chao’s estimator, demonstrating thereby that Chao’s formulation may also provide centered estimates (and not only a lower bound threshold), provided that the sampled communities satisfy a specific type of SAD (species abundance dist…
Chemical host detection and differential attraction in a parasitic pea crab infecting two echinoids
2011
Mechanisms of host detection and host choice are important for mobile parasites or symbionts that frequently move among host individuals. The parasitic pea crab Dissodactylus primitivus is an ectoparasite exploiting asymmetrically two spatangoid echinoid hosts, Meoma ventricosa and Plagiobrissus grandis. The entire life cycle takes place on M. ventricosa, while only adults colonize P. grandis, the host where female's fecundity is the greatest. Dissodactylus primitivus frequently exhibits host-switching, a behaviour that raises the question of host detection. To test if adult crabs are able to detect potential hosts and are attracted to the host where their fitness is greater, crab olfactory…
Habitat assessment by parasitoids: consequences for population distribution
2006
International audience; The ideal free distribution (IFD) is a stable distribution of competitors among resource patches. For equally efficient competitors, equilibrium is reached when the per capita rate of intake equalizes across patches. The seminal version of the IFD assumes omniscience, but populations may still converge toward the equilibrium provided that competitors 1) accurately assess their environment by learning and 2) remain for an optimal (rate-maximizing) time on each encountered patch. In the companion article (Tentelier C, Desouhant E, Fauvergue X. 2006. Habitat assessment by parasitoids: mechanisms for patch time allocation. Behav Ecol. Forthcoming), it is shown that the p…
<p><strong>In BOLD we trust? A commentary on the reliability of specimen identification for DNA barcoding: a case study on burrower bugs …
2016
An assessment was performed regarding the accuracy of various types of data deposited in the Barcode of Life Data system (BOLD) related to the true bug family Cydnidae (Hemiptera: Heteroptera). Taxonomic nomenclature and classification, identification reliability, and the correctness of the data provided in the "Taxon description" were analyzed and commented on with respect to both available versions of the BOLD system, i.e. version 3 and beta version 4. Numerous mistakes in taxonomy, the relevance of the taxa names, and species misidentifications in BOLD version 3 were found and, more importantly, similar errors were detected in BOLD version 4 as well. We suggest that if the BOLD system is…
Morphology of spermatheca in Scutelleridae (Hemiptera: Pentatomoidea) and its taxonomic significance
2016
AbstractStructures of spermatheca in 63 species of Scutelleridae (Hemiptera) representing 46 genera and all subfamilies currently recognised in the family were examined and compared. The morphology of three main parts of the spermatheca (receptacle, intermediate part, and spermathecal duct) was described and three main types of spermatheca in Scutelleridae were identified. The taxonomic importance of spermathecal features for the higher classification of scutellerids is discussed.
Cytotaxonomic investigations on Allium valdecallosum (Amaryllidaceae), a critical species endemic to Morocco
2018
Allium valdecallosum is a critical and poorly known species endemic to Morocco. Its diagnostic features, karyology, seed testa micro-morphology, leaf anatomy, ecology, distribution, conservation status, and taxonomic relationships are examined here.
Presence of uradenia in male adults of the genus Dismegistus (Hemiptera: Heteroptera: Parastrachiidae)
2018
Uradenia, often referred to as paragenital glands, are usually voluminous paired exocrine glands located ventrally in the abdomen mostly on the intersegmental membrane between abdominal segments (= urites) VII-VIII or VIII-IX, depending on sex or the taxon. They have been previously recorded from eight pentatomomorphan families belonging to Coreoidea, Lygaeoidea and Pyrrhocoroidea (Hemiptera: Heteroptera), found either in males, females or both sexes, and were thought to be absent in Pentatomoidea. We report here the first instance of uradenia in a pentatomoid genus, the African Dismegistus Amyot & Serville, 1843 (Parastrachiidae). Only the male adult possesses uradenia located on the i…
Stipa ×fallax (Poaceae: Pooideae: Stipeae), a new natural hybrid from Tajikistan, and a new combination in Stipa drobovii
2017
Stipa ×fallax nothosp. nov . (Poaceae), from western Pamir Alai Mts (Tajikistan), is described and illustrated. Field observation, numerical analyses of morphology, and pollen grain viability data show that it originated from hybridization between S. drobovii and S. macroglossa subsp. macroglossa , species representing sections Smirnovia and Stipa , respectively. Stipa ×fallax is morphologically close to S. ×alaica and S. ×hissarica , but is distinguished by its shortly pilose lower part of the awn and densely pubescent leaves. Characters distinguishing S. ×fallax from its parental species as well as similar hybrid taxa in section Smirnovia that also grow in Central Asia are presented. The …
LMI-based 2D-3D Registration: from Uncalibrated Images to Euclidean Scene
2015
International audience; This paper investigates the problem of registering a scanned scene, represented by 3D Euclidean point coordinates , and two or more uncalibrated cameras. An unknown subset of the scanned points have their image projections detected and matched across images. The proposed approach assumes the cameras only known in some arbitrary projective frame and no calibration or autocalibration is required. The devised solution is based on a Linear Matrix Inequality (LMI) framework that allows simultaneously estimating the projective transformation relating the cameras to the scene and establishing 2D-3D correspondences without triangulating image points. The proposed LMI framewo…
Real-time biomechanical modeling of the liver using Machine Learning models trained on Finite Element Method simulations
2020
[EN] The development of accurate real-time models of the biomechanical behavior of different organs and tissues still poses a challenge in the field of biomechanical engineering. In the case of the liver, specifically, such a model would constitute a great leap forward in the implementation of complex applications such as surgical simulators, computed-assisted surgery or guided tumor irradiation. In this work, a relatively novel approach for developing such a model is presented. It consists in the use of a machine learning algorithm, which provides real-time inference, trained on tens of thousands of simulations of the biomechanical behavior of the liver carried out by the finite element me…