scholarly journals A Genetic Approach to Spanish Populations of the ThreatenedAustropotamobius italicusLocated at Three Different Scenarios

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Beatriz Matallanas ◽  
Carmen Callejas ◽  
M. Dolores Ochando
Keyword(s):  
Freshwater Ecosystems ◽  
Point Of View ◽  
Genetic Approach ◽  
Geographic Pattern ◽  
Mitochondrial Markers ◽  
Mitochondrial Haplotypes ◽  
Data Analyses ◽  
Spanish Populations ◽  
Austropotamobius Italicus ◽  
Current Risk

Spanish freshwater ecosystems are suffering great modification and some macroinvertebrates likeAustropotamobius italicus, the white-clawed crayfish, are threatened. This species was once widely distributed in Spain, but its populations have shown a very strong decline over the last thirty years, due to different factors. Three Spanish populations of this crayfish—from different scenarios—were analysed with nuclear (microsatellites) and mitochondrial markers (COIand16S rDNA). Data analyses reveal the existence of four haplotypes at mitochondrial level and polymorphism for four microsatellite loci. Despite this genetic variability, bottlenecks were detected in the two natural Spanish populations tested. In addition, the distribution of the mitochondrial haplotypes and SSR alleles show a similar geographic pattern and the genetic differentiation between these samples is mainly due to genetic drift. Given the current risk status of the species across its range, this diversity offers some hope for the species from a management point of view.

scholarly journals Combination of nuclear and mitochondrial markers as a useful tool to identify Ctenophthalmus species and subspecies (Siphonaptera: Ctenophthalmidae)

2021 ◽  
Author(s):  
Antonio Zurita ◽  
Cristina Cutillas
Keyword(s):  
Taxonomic Status ◽  
Molecular Study ◽  
Molecular Data ◽  
Point Of View ◽  
Morphological Data ◽  
Molecular Approach ◽  
Nuclear Marker ◽  
Mitochondrial Markers ◽  
Morphological Criteria ◽  
Mtdna Markers

AbstractCtenophthalmus is considered the largest genus within the Order Siphonaptera. From a morphological point of view, only males of this genus can be identified at species and subspecies levels using morphological keys, whereas there are no morphological criteria in order to classify females at these taxonomical levels. Furthermore, the amount of available molecular and phylogenetic data for this genus is quite scarce so far. The main objective of this work was to assess the utility of the combination of nuclear and mitochondrial markers with respect to their ability to differentiate among different subspecies within the Ctenophthalmus genus. With this purpose, we carried out a comparative morphological and molecular study of three different subspecies (Ctenophthalmus baeticus arvernus, Ctenophthalmus nobilis dobyi, and Ctenophthalmus andorrensis catalaniensis) in order to clarify and discuss its taxonomic status. In addition, our study complemented the molecular data previously provided for Ctenophthalmus baeticus boisseauorum and Ctenophthalmus apertus allani subspecies. We sequenced five different molecular markers: EF1-α, ITS1, ITS2, cox1, and cytb. Our results confirmed that morphological data by themselves are not able to discriminate among Ctenophthalmus female taxa; however, the combination of the nuclear marker EF1-α together with mtDNA markers cytb and cox1 constituted a useful taxonomical and phylogenetic tool to solve this issue. Based on these results, we consider that the use of this molecular approach should be gradually used within Ctenophthalmus genus in order to complement its classical taxonomy and clarifying the complex taxonomy of other congeneric species of fleas.

Distribution of Armillaria ostoyae genets in a Pinus resinosa – Pinus banksiana forest

1995 ◽  
Vol 73 (5) ◽  
pp. 776-787 ◽  
Author(s):  
David M. Rizzo ◽  
Robert A. Blanchette ◽  
Georgiana May
Keyword(s):  
Pinus Banksiana ◽  
Pinus Resinosa ◽  
Molecular Data ◽  
Incompatibility Group ◽  
Ecological Processes ◽  
Somatic Incompatibility ◽  
Mitochondrial Markers ◽  
Armillaria Ostoyae ◽  
Mitochondrial Haplotypes ◽  
Single Exception

Diploid isolates of Armillaria ostoyae were obtained from 278 trees (including stumps, Pinus banksiana seedlings, and hardwood regeneration) and 78 solitary basidiomes on three 50 × 25 m plots (two clearcut and one uncut) in a Pinus resinosa – P. banksiana stand in northern Minnesota. Based on pairings among 439 isolates, 16 somatic incompatibility groups of A. ostoyae were distinguished on the three plots. Analysis of nuclear and mitochondrial markers suggests that many of the A. ostoyae genets are closely related and were possibly established by sib-related basidiospores. Analysis of molecular markers of 95 isolates representing the 16 somatic incompatibility groups delineated 16 nuclear and 8 mitochondrial haplotypes. All isolates tested within a somatic incompatibility group were identical for nuclear and mitochondrial haplotypes; a single exception consisted of a somatic incompatibility group with three different nuclear genotypes. The combination of somatic incompatibility and molecular data indicates the presence of at least 18 genets on the site. Large (up to 140-m diameter), spatially continuous genets intermingled with small, recently established genets and older, fragmented genets. The approach identified genetic and ecological processes; these include breeding strategies and pathogenicity. Key words: Armillaria ostoyae, somatic incompatibility, population structure, mitochondria.

Drought as a Disturbance in Forests

Ecology ◽  
2017 ◽  
Author(s):  
Rafael Poyatos ◽  
Enrique Doblas-Miranda
Keyword(s):  
Physiological Stress ◽  
Large Body ◽  
Freshwater Ecosystems ◽  
Point Of View ◽  
Mild Stress ◽  
Ecosystem Structure ◽  
Functional Responses ◽  
Early 21St Century ◽  
And Function ◽  
Agent Of Change

Drought is a situation of water deficit of a system, compared to normal conditions. Operational definitions of drought (i.e., those used to identify specific drought events) change depending upon the system under consideration, but they have been historically restricted to climatic, agricultural, hydrologic, and socioeconomic systems. From an ecologic point of view, the literature on drought-related impacts on ecosystems has grown dramatically only in recent years, prompted by our need to predict such impacts under the drier conditions projected for many areas of the Earth as a result of climate change. This article provides a guide to the literature addressing the role of drought as an agent of change in of ecosystem structure and function mediated by vegetation responses. The study of drought responses in plants has traditionally been led by agronomists and plant ecophysiologists, with an emphasis on the understanding of physiological stress or plastic responses. Here we will focus not on mild stress, but on extreme functional responses and drought-related persistent changes in terrestrial, natural, and seminatural ecosystems, considering that agricultural or freshwater ecosystems merit their own review and are beyond the scope of this article. Because of the increasing interest in the causes and consequences of drought-induced vegetation dieback since the early 21st century, many of the references included in this article are relatively recent. This large body of research has been mostly developed for woody communities, and the majority of studies selected here are hence based on woodlands. Nevertheless, we recommend the “Drought” section in the Oxford Bibliography on the “Grassland Biome” for further information.

scholarly journals How Do Eutrophication and Temperature Interact to Shape the Community Structures of Phytoplankton and Fish in Lakes?

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 779 ◽  
Author(s):  
Liess Bouraï ◽  
Maxime Logez ◽  
Christophe Laplace-Treyture ◽  
Christine Argillier
Keyword(s):  
Community Structure ◽  
Global Change ◽  
Anthropogenic Activities ◽  
Freshwater Ecosystems ◽  
Point Of View ◽  
Aquatic Communities ◽  
Biomass Ratio ◽  
The Relationship ◽  
Average Body

Freshwater ecosystems are among the systems most threatened and impacted by anthropogenic activities, but there is still a lack of knowledge on how this multi-pressure environment impacts aquatic communities in situ. In Europe, nutrient enrichment and temperature increase due to global change were identified as the two main pressures on lakes. Therefore, we investigated how the interaction of these two pressures impacts the community structure of the two extreme components of lake food webs: phytoplankton and fish. We modelled the relationship between community components (abundance, composition, size) and environmental conditions, including these two pressures. Different patterns of response were highlighted. Four metrics responded to only one pressure and one metric to the additive effect of the two pressures. Two fish metrics (average body-size and biomass ratio between perch and roach) were impacted by the interaction of temperature and eutrophication, revealing that the effect of one pressure was dependent on the magnitude of the second pressure. From a management point of view, it appears necessary to consider the type and strength of the interactions between pressures when assessing the sensitivity of communities, otherwise their vulnerability (especially to global change) could be poorly estimated.

scholarly journals Gammarus Orinos n. sp. from the Massif Central (France): Its Genetic and Morphological distinction from Gammarus Ibericus Margalef, 1951 (Crustacea, Amphipoda)

1984 ◽  
Vol 54 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Sjouk Pinkster ◽  
Adolf Scholl
Keyword(s):  
Western Europe ◽  
Point Of View ◽  
Type Locality ◽  
Careful Examination ◽  
Freshwater Species ◽  
Separate Species ◽  
Massif Central ◽  
Morphological Distinction ◽  
Spanish Populations ◽  
Morphological Differences

Until 1974 Gammarus ibericus was known only from the type-locality in Spain. In that year, Goedmakers recorded the species from many localities in the Massif Central, France. Indeed, these populations show a great morphological resemblance to the Spanish ones. These French populations were used in cross-breeding experiments with other populations from southern France, without result. Attempts to hybridize these populations with the G. ibericus from the type-locality also failed to produce any offspring. Electrophoretic studies showed that the French and Spanish populations are very different from a biochemical point of view; these differences are much greater than between any of the known freshwater species (or populations) from western Europe. It is therefore decided that the populations from the Massif Central belong to a separate species: G. orinos n. sp. Careful examination of hundreds of specimens from both Spain and France showed that minor but constant morphological differences exist between the two species.

scholarly journals Considerações acerca da filogenia de Trichoptera Kirby 1813: da análise dos dados para as hipóteses ou dos cenários para os dados

2009 ◽  
Vol 2 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Adolfo Ricardo Calor
Keyword(s):  
Aquatic Insects ◽  
A Priori ◽  
Marine Species ◽  
Conceptual Structure ◽  
Freshwater Ecosystems ◽  
Morphological Data ◽  
Benthic Macroinvertebrate ◽  
Taxon Sampling ◽  
Data Analyses ◽  
The World

Trichoptera compreendem a maior ordem de insetos estritamente aquáticos e constitui a maior proporção da comunidade dos macroinvertebrados bentônicos, com uma fauna mundial em torno de 13.000 espécies descritas para os ecossistemas dulcícolas, além de algumas espécies marinhas da família Chathamiidae, encontradas na Nova Zelândia e Austrália. Nos últimos 40 anos, várias hipóteses da filogenia de Trichoptera têm sido propostas, algumas com amostragens taxonômicas bastante restritas (outras mais completas), algumas com polarização dos caracteres baseada em cenários evolutivos pré-estabelecidos (outras com métodos mais objetivos), algumas apenas com dados morfológicos (outras utilizando dados de diferentes fontes, como morfológicos, moleculares, etológicos) e, por fim, algumas propostas oriundas de análises utilizando máxima parcimônia ou algoritmos bayesianos. O objetivo deste artigo é integrar o conhecimento acerca da filogenia de Trichoptera a fim de construir um panorama elucidativo da atual situação deste táxon e, conseqüentemente, fornecer a estrutura conceitual para o desenvolvimento de trabalhos futuros acerca da filogenia de Trichoptera.   Considerations on phylogeny of Trichoptera Kirby 1813: from data analyses to hypotheses or from scenarios to data Abstract. Trichoptera are the major order among the aquatic insects and constitute a large proportion of benthic macroinvertebrate community. There are about 13000 described species of caddisflies in the world from freshwater ecosystems, and some marine species of Chathamiidae from New Zealand and Australia. In the last 40 years, several different hypotheses of Trichoptera’s phylogeny have been proposed, some analyses with reduced taxon sampling (other analyses with more complete data basis), some analyses with character polarization based in a priori evolutionary scenarios (other with more objective methods), some analyses using only morphological data (other using different data sources as morphology, molecular, ethological data), and some proposals from analyses using maximum parsimony or using Bayesian algorithms. The aim of this paper is integrate the taxonomical knowledge of phylogeny of Trichoptera to building an elucidative landscape and, consequently, to frame the conceptual structure to the development of the future phylogenetic works on Trichoptera systematics.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

How a sheperd guides a sheep herd?

1984 ◽  
Vol 75 ◽  
pp. 331-337
Author(s):  
Richard Greenberg
Keyword(s):  
Point Of View ◽  
Single Ring ◽  
Damping Effects ◽  
Ring Particle

ABSTRACTThe mechanism by which a shepherd satellite exerts a confining torque on a ring is considered from the point of view of a single ring particle. It is still not clear how one might most meaningfully include damping effects and other collisional processes into this type of approach to the problem.

The growth of mica polytypes as studied by conventional and high-resolution TEM

1983 ◽  
Vol 41 ◽  
pp. 174-177
Author(s):  
A. Baronnet ◽  
M. Amouric
Keyword(s):  
Water Pressure ◽  
Point Of View ◽  
Temperature Fields ◽  
Natural Occurrence ◽  
Growth Mechanisms ◽  
Long Period ◽  
High Resolution Tem ◽  
Layer Stacking ◽  
Experimental Works ◽  
Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

Radiation Damage in Ceramics

1982 ◽  
Vol 40 ◽  
pp. 600-603
Author(s):  
T. E. Mitchell ◽  
M. R. Pascucci ◽  
R. A. Youngman
Keyword(s):  
Radiation Damage ◽  
Outer Space ◽  
Point Of View ◽  
Nuclear Waste Storage ◽  
Waste Storage ◽  
Storage Media ◽  
Transmission Electron ◽  
Fundamental Point ◽  
Small Defect ◽  
Present Understanding

1. Introduction. Studies of radiation damage in ceramics are of interest not only from a fundamental point of view but also because it is important to understand the behavior of ceramics in various practical radiation enyironments- fission and fusion reactors, nuclear waste storage media, ion-implantation devices, outer space, etc. A great deal of work has been done on the spectroscopy of point defects and small defect clusters in ceramics, but relatively little has been performed on defect agglomeration using transmission electron microscopy (TEM) in the same kind of detail that has been so successful in metals. This article will assess our present understanding of radiation damage in ceramics with illustrations using results obtained from the authors' work.

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