Search results for " divergence"
showing 10 items of 131 documents
How endogenous asymmetries in interregional market access trigger regional divergence
2005
International audience; We investigate how asymmetric trade patterns in differentiated products affect the regional distribution of economic activities. The asymmetry in interregional market access is an endogenous result of price competition and industry location and arises for intermediate values of trade costs. We show that the emergence of one-way trade in differentiated products gives rise to strong agglomeration forces and leads to the absorption of the smaller region's industry by the larger region. The number of spatial equilibria increases once the pattern of trade is endogenously accounted for.
Genetic-based evaluation of management units for sustainable vendace (Coregonus albula) fisheries in a large lake system
2022
Abstract The goal of the processing industry, trade and consumers is to get eco-labelled freshwater fish products from sustainable fisheries into the market as soon as possible. The fourth largest natural lake system in Europe, the Saimaa lake system supports a fishery for vendace (Coregonus albula). Certification of the fishery requires an understanding of population structure to help determine the number and spatial extent of management units. In this study, we analysed the genetic diversity of local vendace populations in the Saimaa lake system and aimed to identify the conservation and management units of vendace. Within the Saimaa, the genetic divergence between local populations of ve…
Reduced reference 3D mesh quality assessment based on statistical models
2015
International audience; During their geometry processing and transmission 3D meshes are subject to various visual processing operations like compression, watermarking, remeshing, noise addition and so forth. In this context it is indispensable to evaluate the quality of the distorted mesh, we talk here about the mesh visual quality (MVQ) assessment. Several works have tried to evaluate the MVQ using simple geometric measures, However this metrics do not correlate well with the subjective score since they fail to reflect the perceived quality. In this paper we propose a new objective metric to evaluate the visual quality between a mesh with a perfect quality called reference mesh and its dis…
Behavioral reproductive isolation among sympatric strains of Brachionus plicatilis Müller 1786: insights into the status of this taxonomic species
1995
We present results on cross-mating experiments using Brachionus plicatilis strains collected in three ponds of a coastal marsh (Torreblanca Marsh, Castellon, Spain). These strains were known to differ widely both in morphology and allozyme patterns from a previous study, where they were grouped into three genetically different clonal groups. Although some of the strains co-occurred in the same pond and sexual periods overlapped, no gene flow was found among them. Our first objective was to determine whether behavioral reproductive isolation was responsible for the absence of interbreeding. A second objective was to explore the relationship between sexual isolation and genetic divergence. We…
Vers une approche globale de l'évolution des Hominidés
1998
Abstract Two models of diversification of the common ancestor of gorillas, chimpanzees and men can be proposed on the basis of the distribution of chromosomal rearrangements in extant species and reconsideration of the role played by climate. The small genetic divergence between chimpanzees and humans is greatly amplified at the morphological level, thus constituting the ‘human paradox’. This paradox is resolved by the economical and flexible evolutionary mechanism of mutations in regulator genes and the heterochronies they control, which are the true internal clocks of evolution. Changes in cranial morphology are quantified and used to analyse and explain the steps in the transition from g…
Using DNA barcodes to detect non-indigenous species: the case of the Asian copepod Mesocyclops pehpeiensis Hu, 1943 (Cyclopidae) in two regions of th…
2015
To date, little attention has been paid to analyses of copepods as exotic species. The genusMesocyclops, a freshwater cyclopoid, has a worldwide distribution, but individual species within the genus have a quite restricted geographical range.Mesocyclops pehpeiensisHu, 1943 is a Central-East Asian species, rarely found outside of this area, and when it appears should be considered as non-native. Based on morphology and DNA barcode analyses, using the COI gene, we confirmed records ofM. pehpeiensisin two ponds in Mexico and in a rice paddy near Valencia, Spain. The morphology of this species, based on morphometric analyses, was found to be variable, but DNA barcoding confirmed the same identi…
Recolonization after habitat restoration leads to decreased genetic variation in populations of a terrestrial orchid
2012
Colonization is crucial to habitat restoration projects that rely on the spontaneous regeneration of the original vegetation. However, as a previously declining plant species spreads again, the likelihood of founder effects increases through recurrent population founding and associated serial bottlenecks. We related Amplified Fragment Length Polymorphism markers genetic variation and fitness to colonization history for all extant populations of the outcrossing terrestrial orchid Dactylorhiza incarnata in an isolated coastal dune complex. Around 1970, D. incarnata suffered a severe bottleneck yet ultimately persisted and gradually spread throughout the spatially segregated dune slacks, aided…
Larval morphology, genetic divergence, and contrasting levels of host manipulation between forms of Pomphorhynchus laevis (Acanthocephala)
2004
Studies on parasite species with a wide geographic and ecological range may be confounded by still equivocal taxonomic identification. Here, we investigated genetic polymorphism and behavioural changes induced in a common intermediate host, in two different forms of Pomphorhynchus laevis based on the morphology of the larval infective stage (cystacanth). A 'smooth type' (S) and a 'wrinkled type' (W) of cystacanth were distinguished based on their surface and shape. We analysed sequence divergence at both nuclear (ribosomal gene 18S rDNA, and ribosomal internal transcribed spacers, ITS1/ITS2) and mitochondrial (cytochrome c oxidase subunit 1) genes of P. laevis cystacanths and adults at vari…
Mitochondrial Dna Sequence Variation among Geographic Strains of Diamondback Moth (Lepidoptera: Plutellidae)
1997
We examined genetic variation among 6 geographic strains of diamondback moth, Plutella xylostella (L.), using 365 base pairs of the mitochondrial gene encoding cytochrome oxidase I (COI). No sequence variation was detected within 5 of the 6 strains; 1 strain contained 2 haplotypes that differed by a single base substitution (0.27%). Sequence differences between strains of diamondback moth from Hawaii, the Philippines, and Pennsylvania ranged from 0 to 0.82%. With one exception, base pair substitutions among strains resulted in synonymous codons and did not alter amino acid sequence. Genetic divergence between strains of diamondback moth was not correlated with geographic distances between t…
Conserved and newly acquired roles of PIF1 homologs in tomato (Solanum lycopersicum)
2021
ABSTRACTPHYTOCHROME INTERACTING FACTORS (PIFs) are transcription factors that interact with the photoreceptors phytochromes and integrate multiple signaling pathways related to light, temperature, defense and hormone responses. PIFs have been extensively studied inArabidopsis thaliana, but less is known about their roles in other species. Here, we investigate the role of the two homologs of PIF1 found in tomato (Solanum lycopersicum), namely PIF1a and PIF1b. Analysis of gene expression showed very different patterns, indicating a potential evolutionary divergence in their roles. At the protein level, light regulated the stability of PIF1a, but not PIF1b, further supporting a functional dive…