scholarly journals The effect of dominant species on numbers and agę structure of Iris sibirica L. population on blue moor-grass meadow in southern Poland

2011 ◽  
Vol 76 (2) ◽  
pp. 165-173 ◽  
Author(s):  
Kinga Kostrakiewicz
Keyword(s):  
Seed Production ◽  
Age Structure ◽  
Vegetative Propagation ◽  
Dominant Species ◽  
Floristic Composition ◽  
Field Observations ◽  
Grass Meadow ◽  
High Level ◽  
Two Populations ◽  
Clonal Species

Two populations of <em>Iris sibirica</em>, a clonal species protected by law in Poland, occurring in patches of <em>Molinietum caeruleae</em>, of similar floristic composition although with different dominant species, were studied. In the Stanisławice locality, species with a high competitive potential prevailed, contrary to the Opatkowice locality, where the species of low competitive potential dominated. It was established that vegetative propagation ensures the continued presence of populations in both localities, although the proximity of plants with high competitive potential limits the vegetative propagation of ramet clusters of <em>Iris sibirica</em>. Despite the high level of seed production, the recruitment of seedlings in both patches is possible only in artificially created gaps. The field observations support the conclusion that creating gaps allowing for germination of seeds and development of seedlings, as well as eliminating expansive neighbours allowing proliferation of ramet clusters of <em>Iris sibirica</em>, is an affective way of protecting populations of this species.

scholarly journals Mycorrhiza – Benefits, Influence, Diagnostic Method

1970 ◽  
Vol 66 (1) ◽  
Author(s):  
Vlad STOIAN ◽  
Viorel FLORIAN
Keyword(s):  
Soil Structure ◽  
Dominant Species ◽  
Diagnostic Method ◽  
Floristic Composition ◽  
Soil Microflora ◽  
Mycorrhizal Symbiosis ◽  
Physiological Factors ◽  
High Level ◽  
The Relationship ◽  
Made In

By studying mycorrhizal symbiosis, another important step is made in knowing the relationship between plants and soil microflora. Benefits that these symbiosis bring to plants and ecosystem are semnificative for the interpretation of physiological factors, like: extending the volume of soil accessible to plants, acquiring nutrient forms that would not normally be available to plants; for the ecosystem an important role is to soil structure and mechanical aggregation. In the pasture that we studied in the Apuseni Mountains we found as dominant species Carex hirta, percent in the floristic composition is 35-40%, and that is the primary reason for studying this plant. The study area is positioned at 2 meters far from the forest and the soil is caracterized by a big humidity – the subteran water is at a high level. To identify the influence of the forest, of the humidity and the relation with other plants in the pasture, first step was to find that plants of Carex hirta is colonized by mycorrhizal symbiosis. We harvest the plants with root from a 15 to 20 cm deep and we colored teh roots with a solution of ink with vinegar. The proposed method for diagnosis of mycorrhizal colonization on Carex hirta roots is specific for the area where the studies took place.

Co-expression of insulin and somatostatin genes in pancreatic endocrine cells selected for their high level of insulin gene transcription

1992 ◽  
Vol 101 (4) ◽  
pp. 795-799
Author(s):  
C. Saulnier-Michel ◽  
M. Fromont-Racine ◽  
R. Pictet
Keyword(s):  
Endocrine Cells ◽  
Selective Pressure ◽  
Cell Types ◽  
Insulin Gene ◽  
Regulatory Sequences ◽  
Endogenous Insulin ◽  
Pancreatic Endocrine Cells ◽  
Gene Regulatory ◽  
High Level ◽  
Two Populations

RW cells are pancreatic endocrine RIN cells that have been stably transfected with a chimeric gene that places the expression of the dominant selection gpt gene under the control of the insulin gene regulatory sequences. These RW cells were examined for hormone content using immunocytochemistry. This analysis shows that: first, there are cells that are negative for insulin although they were cultured under selective pressure. Second, there is a higher proportion of somatostatin-producing cells than in the parental RIN cells; these somatostatin cells form two populations: one of cells containing only somatostatin and, surprisingly, one made of cells containing both insulin and somatostatin. Thus: (1) expression of the transfected and endogenous insulin regulatory sequences is not regulated in a coordinate fashion; (2) the presence of both hormones in the same cell suggests that the regulation of the expression of insulin and somatostatin genes and the differentiation pathway of the two respective cell types may be closely related.

scholarly journals Analysis of Genetic Diversity in three Kazakh Sheep using 12 Microsatellites

2018 ◽  
Vol 7 (4.38) ◽  
pp. 122
Author(s):  
Kairat Dossybayev ◽  
Aizhan Mussayeva ◽  
Bakytzhan Bekmanov ◽  
Beibit Kulataev
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Mean Value ◽  
Fixation Index ◽  
Merino Sheep ◽  
Str Markers ◽  
Sheep Breeds ◽  
Str Loci ◽  
High Level ◽  
Two Populations

The genetic structure of three Kazakh sheep breeds was examined by using 12 microsatellite loci. A total of 144 alleles were detected from the 12 STR loci, with a mean value of 12.0. The highest allele diversity was found at the locus CSRD247 (16 alleles). PIC value showed that all studied STR markers are more informative and appropriate for genetic analysis of three Kazakh sheep populations. Beside of INRA006, all markers had high level of genetic variability. As Fixation index shows, the excess of the heterozygosity was observed only in loci MAF065. Obtained number of private alleles in Edilbai, Kazakh Arkhar Merino and Kazakh Fine-wool sheep were 25, 17 and 15 respectively. Genetic diversity was higher in Edilbai population than in other two populations. The genetic variability was lower in Kazakh Arkhar Merino sheep than in the Edilbai and Kazakh Fine-wool sheep breeds. The genetic distance was the largest between Edilbai and Kazakh Arkhar Merinos. Also, the moderate differentiation was observed between Edilbai and Kazakh Arkhar Merinos.   

IDENTIFYING CONSERVATION PRIORITY AREAS IN THE MARAÑÓN VALLEY (PERU) BASED ON FLORISTIC INVENTORIES

2015 ◽  
Vol 73 (1) ◽  
pp. 95-123 ◽  
Author(s):  
J. L. Marcelo-Peña ◽  
I. Huamantupa ◽  
T. Särkinen ◽  
M. Tomazello
Keyword(s):  
Species Diversity ◽  
Plant Species ◽  
Dominant Species ◽  
Vascular Plant ◽  
Conservation Areas ◽  
Seasonally Dry ◽  
Vascular Plant Species ◽  
Nationally Representative ◽  
The One ◽  
High Level

In this study, we report species diversity and endemism of the poorly known but highly diverse Seasonally Dry Tropical Forest (SDTF) flora of the Marañón valley in northern Peru. We characterise woody vascular plant species diversity across the valley in order to define the conservation value of the area at national and international level. Based on 32 rapid botanical inventories, 92 plots of 50 × 20 m, and a herbarium study across local and international herbaria, we report 440 woody vascular plant species of which 143 (33%) are endemic to the valley. Two centres of endemism within the valley are identified, each with clear elevational zonation of diversity. Data show that the Marañón valley is a good representative of Peruvian SDTFs as a whole, with an average of 56% SDTF species and 78% SDTF genera found in the one valley. The results show that there is wide variation in the set of dominant species across the valley, and that many local endemics are locally abundant unlike in neighbouring SDTFs where the dominant species are all geographically widespread. Our results demonstrate that the Marañón includes a rare combination of both nationally representative yet globally unique plant species, which makes the valley an ideal conservation target. The high level of endemism structured within elevational zones implies that conservation areas should be established across elevational zones in order to maximise the protection of this globally unique flora.

scholarly journals Dynamique d'établissement d'un peuplement bi-étagé de bouleau blanc et de sapin baumier en zone boréale

1993 ◽  
Vol 69 (2) ◽  
pp. 173-177 ◽  
Author(s):  
Louis Bélanger ◽  
Daniel Allard ◽  
Philippe Meek
Keyword(s):  
Age Structure ◽  
Initial Period ◽  
Abies Balsamea ◽  
Floristic Composition ◽  
Balsam Fir ◽  
White Birch ◽  
Vegetation Dynamic ◽  
Local Conditions ◽  
Regeneration Pattern ◽  
Seed Sources

The age structure of a boreal two-storied stand formed by an upperstory of white birch (Betula papyrifera Marsh.) with an understory of balsam fir (Abies balsamea (L.) Mill.) was analysed. The establishment of this 50-year stand followed a burn that ran through a cut-over area. The objective was to verify if the establishment of the fir understory followed the traditional succession model or the initial floristic composition model. The age structure analysis indicated an immediate and rapid establishment of white birch during a period of 6 years after the fire. Establishment of fir, however, was initiated only 16 years after the fire. Peak establishment was 33 years after the fire. Fir regeneration followed a cycle. The regeneration pattern was characterized by the absence of fir establishment the first 16 years after the fire, followed by sporadic fir regeneration the next 12 years, then by a 13-year period of abundant regeneration after which there was a complete halt to fir regeneration. So, in this case, the successional model was more fit to describe the dynamics of balsam fir. The absence of fir regeneration during the initial period after the fire could be explained by the absence of the nearby fir seed sources due to harvesting. However, the total absence of fir establishment during the last period is more difficult to explain. Seedbed evolution since the fire could possibly be in cause. This and other studies indicate that in the boreal balsam fir-white birch ecoclimatic domain vegetation dynamic after fire does not limit itself to one pathway. Stand regeneration after fire is significantly affected by local conditions.

Demographic expansion and high level of matrilineal diversity in two populations of East African Baggara cattle

2021 ◽  
Author(s):  
Sumaya Kambal ◽  
Amina E. Abdelrahim ◽  
Olivier Hanotte ◽  
Ryo Nakao ◽  
Abeer M. Alkhaibari ◽  
...  
Keyword(s):  
Demographic Expansion ◽  
East African ◽  
High Level ◽  
Two Populations

Management of ACCase-Inhibiting Herbicide-Resistant Smooth Barley (Hordeum glaucum) in Field Pea with Alternative Herbicides

2016 ◽  
Vol 30 (2) ◽  
pp. 441-447 ◽  
Author(s):  
Lovreet S. Shergill ◽  
Benjamin Fleet ◽  
Christopher Preston ◽  
Gurjeet Gill
Keyword(s):  
Seed Production ◽  
Negative Relationship ◽  
South Australia ◽  
Field Pea ◽  
Forage Yield ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Large Yield ◽  
High Level ◽  
The Impact

Smooth barley is an annual weed species that is infesting crops and pastures in South Australia. Complicating control options is the presence of herbicide-resistant biotypes. A field trial was conducted to identify alternative herbicides for the management of acetyl coenzyme A carboxylase (ACCase)-inhibiting herbicide-resistant smooth barley in field pea. Preplant (PP) soil applications of pyroxasulfone; prosulfocarb plus S-metolachlor; dimethenamid-P; propyzamide; trifluralin alone or with triallate or with diuron; or imazamox applied POST were evaluated for their effectiveness and crop safety. Propyzamide, pyroxasulfone, or imazamox applied POST provided a high level of smooth barley control, did not cause any crop injury, and increased field pea grain or forage yield compared with the nontreated. Furthermore, propyzamide or pyroxasulfone reduced panicle density and seed production in smooth barley, whereas the effectiveness of POST imazamox varied over the two seasons. Dimethenamid-P reduced the impact of smooth barley on field pea yield, but cause stunting, and was less effective than propyzamide, pyroxasulfone, and imazamox in reducing smooth barley seed production. Negative relationship between field pea yield and smooth barley panicle density indicated that smooth barley is highly competitive in field pea crops and can cause large yield losses. The results of this investigation suggest that propyzamide or pyroxasulfone applied PP and imazamox applied POST could be used effectively in the field for the management of ACCase-inhibiting herbicide-resistant smooth barley in South Australia.

The demography of a dominant Amazon liana species exhibits little environmental sensitivity

2015 ◽  
Vol 32 (1) ◽  
pp. 79-82 ◽  
Author(s):  
Luciana de Campos Franci ◽  
Jens-Christian Svenning ◽  
Henrik Balslev ◽  
Fernando Roberto Martins ◽  
Jacob Nabe-Nielsen
Keyword(s):  
Dominant Species ◽  
Environmental Gradients ◽  
Floristic Composition ◽  
Environmental Variation ◽  
Common Species ◽  
Amazon Forest ◽  
Vegetation Density ◽  
Vital Rates ◽  
Relative Growth ◽  
Positive Effect

Abstract:Despite its high plant diversity, the Amazon forest is dominated by a limited number of highly abundant, oligarchic tree and liana species. The high diversity can be related to specific habitat requirements in many of the less common species, but fewer studies have investigated the characteristics of the dominant species. To test how environmental variation may contribute to the success of dominant species we investigated whether the vital rates of the abundant liana Machaerium cuspidatum is sensitive to canopy height, topographic steepness, vegetation density, soil components and floristic composition across an Ecuadorian Amazon forest. The population was inventoried in 1998 and in 2009. Plants were divided into seedling-sized individuals, non-climbers and climbers. Out of 448 seedling-sized plants 421 died, 539 of 732 non-climbers died, and 107 of 198 climbers died. There was weak positive effect of dense understorey on the relative growth rate of climbers. The mortality of seedling-sized plants was higher in areas with intermediate slope, but for larger plants mortality was not related to environmental variation. The limited sensitivity of the vital rates to environmental gradients in the area suggests that ecological generalism contributes to the success of this dominant Amazonian liana.

Gyrodactylids (Gyrodactylidae, Monogenea) infecting Oreochromis niloticus niloticus (L.) and O. mossambicus (Peters) (Cichlidae): A pan-global survey

2010 ◽  
Vol 55 (3) ◽  
Author(s):  
Adriana García-Vásquez ◽  
Haakon Hansen ◽  
Kevin Christison ◽  
Miquel Rubio-Godoy ◽  
James Bron ◽  
...  
Keyword(s):  
South African ◽  
Oreochromis Niloticus ◽  
Dominant Species ◽  
Juvenile Fish ◽  
Principal Component ◽  
Oreochromis Mossambicus ◽  
Molecular Data ◽  
Molecular Analyses ◽  
Nile Tilapia Oreochromis Niloticus ◽  
Two Populations

AbstractGyrodactylus infections in intensively-reared populations of Nile tilapia, Oreochromis niloticus niloticus, have been associated world-wide with high mortalities of juvenile fish. In this study, 26 populations of Gyrodactylus parasitising either O. n. niloticus or Mozambique tilapia, Oreochromis mossambicus, were sampled from fourteen countries and compared with type material of Gyrodactylus cichlidarum Paperna, 1968, Gyrodactylus niloticus (syn. of G. cichlidarum) and Gyrodactylus shariffi Cone, Arthur et Bondad-Reantaso, 1995. Representative specimens from each population were bisected, each half being used for morphological and molecular analyses. Principal component analyses (PCA) identified five distinct clusters: (1) a cluster representing G. cichlidarum collected from O. n. niloticus from 13 countries; (2) the G. shariffi paratype; (3) three specimens with pronounced ventral bar processes collected from two populations of Mexican O. n. niloticus (Gyrodactylus sp. 1); (4) four specimens collected from an Ethiopian population nominally identified as O. n. niloticus (Gyrodactylus sp. 2); (5) nine gyrodactylids from South African O. mossambicus (Gyrodactylus sp. 3). Molecular analyses comparing the sequence of the ribosomal transcribed spacer regions (ITS 1 and 2) and the 5.8S gene from the non-hook bearing half of worms representative for each population and for each cluster of parasites, confirmed the presence of G. cichlidarum in most samples analysed. Molecular data also confirmed that the DNA sequence of Gyrodactylus sp. 2 and Gyrodactylus sp. 3 (the morphologically-cryptic group of South African specimens from O. mossambicus) differed from that of G. cichlidarum and therefore represent new species; no sequences were obtained from Gyrodactylus sp. 1. The current study demonstrates that G. cichlidarum is the dominant species infecting O. n. niloticus, being found in 13 of the 15 countries sampled.

scholarly journals Unexpected parasitism of Douglas-fir seed chalcid limits biocontrol options for invasive Douglas-fir in New Zealand

2021 ◽  
Vol 74 (1) ◽  
pp. 70-77
Author(s):  
Sonia Lee ◽  
Simon V. Fowler ◽  
Claudia Lange ◽  
Lindsay A. Smith ◽  
Alison M. Evans
Keyword(s):  
Biological Control ◽  
New Zealand ◽  
Seed Production ◽  
Biocontrol Agent ◽  
Biological Control Agent ◽  
Parasitoid Wasp ◽  
Control Agent ◽  
Douglas Fir ◽  
Seed Predator ◽  
High Level

Douglas-fir seed chalcid (DFSC) Megastigmus spermotrophus, a small (3 mm long) host-specific seed-predatory wasp, was accidentally introduced into New Zealand in the 1920s. Concern over DFSC reducing Douglas-fir seed production in New Zealand led to an attempt at biocontrol in 1955 with the release, but failed establishment, of the small (2.5 mm long) parasitoid wasp, Mesopolobus spermotrophus. We investigated why DFSC causes little destruction of Douglas-fir seed in New Zealand (usually <20%) despite the apparent absence of major natural enemies. Douglas-fir seed collections from 13 New Zealand sites yielded the seed predator (DFSC) but also potential parasitoids, which were identified using morphology and partial COI DNA sequencing. DFSC destroyed only 0.15% of Douglas-fir seed. All parasitoids were identified as the pteromalid wasp, Mes. spermotrophus, the host-specific biocontrol agent released in 1955. Total parasitism was 48.5%, but levels at some sites approached 90%, with some evidence of density-dependence. The discovery of the parasitoid Mes. spermotrophus could indicate that the biocontrol agent released in 1955 did establish after all. Alternatively, Mes. spermotrophus could have arrived accidentally in more recent importations of Douglas-fir seed. The high level of parasitism of DFSC by Mes. spermotrophus is consistent with DFSC being under successful biological control in New Zealand. Suppression of DFSC populations will benefit commercial Douglas-fir seed production in New Zealand, but it also represents the likely loss of a potential biological control agent for wilding Douglas-fir.

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