جستجوی مقالات مرتبط با کلیدواژه « Principal Component Analysis » در نشریات گروه « زیست شناسی »

During 2020-2021, to investigate the morphological variation of Chelon auratus, a total of 170 specimens were collected using beach seine nets from the shores of Astara (23 specimens), Anzali (33 specimens), Kiashahr (23 specimens), Langaroud (27 specimens), Roudsar (7 specimens), Chalous (30 specimens), Mahmoudabad (14 specimens), and Sari (13 specimens). At the sampling sites, after imaging from the left side of the specimens, 14 landmark points were defined and digitized on the two-dimensional images using the tpsDig2 software. The obtained data, after generalized Procrustes analysis, were analyzed using multivariate statistical analyses including principal component analysis (PCA), canonical variate analysis (CVA), and cluster analysis (CA). The deformation patterns of each population were illustrated in relation to consensus shapes on the deformation grids. The results showed significant differences in the body shape of the studied populations (P<0.05). These differences, related to head length, body depth, dorsal fin position, and caudal peduncle length, suggest the separation of populations in response to environmental conditions.

High increase in societies’ needs to wood and its products followed by decrease in forests lands leads to give special importance to forest plantation. The study aims to consider the impact of pure and mixed plantation of Eucalyptus and Ziziphus on above-ground growth features and soil properties in Laleh Park in Dezful . A complete randomly design was conducted with two treatments of pure plantation of Eucalyptus cameldulensis, and mixed plantation of Eucalyptus and Ziziphus with three repetitions. In total, 42 sample plots were determined. The quantity characteristics were diameter at breast height , diameter of collar , height of tree , crown coverage, slender coefficient , Form quotient, volume, leaf dry mass , leaf area index , total growth ring width , and wood density. To determine the chemical and physical properties of soil, three soil samples from each plot at the depth of 0 to 30 cm were collected and a mixed sample was transformed to the laboratory for the further works. The results showed that DBH, DC, H, V, TWR of Eucalyptus cameldulensis in pure plantation was significantly higher than those of mixed plantation. According to the analysis of main components and growth features of Eucalyptus cameldulensis, two groups were separated across first and second axes as each of them indicated high adaptation with place of sampling (mixed or pure mass). The measuring soil properties between two plantations showed that potassium, nitrogen, phosphor, organic carbon, and saturation moisture content were significantly more than that in pure plantation.

To evaluate the effect of drought stress on grain yield, yield component, morphologic and phonological traits on 30 genotypes of wheat, an experiment in the form randomized complete block with three replication at 2 levels of irrigation (normal and stress), was carried out. Results showed that the studied genotypes were significantly different in terms of grain yield, 100-seed weight, number of seeds per pod, number of pods per plant, day to maturity, and seed size under stress and non-stress conditions. According to the results, it can be seen that Kavir, Pishtaz and Helmand cultivars showed the lowest yield reduction and Navid, Karim and Alvand cultivars showed the highest grain yield decrease among all cultivars. The analysis of tolerance index correlation showed index of tolerance stress, using mean and using numeral mean are the best indexes for identifying genotype with high yield in this test According to the results of phenotypic correlations, stepwise regression, path analysis and principal component analysis in both normal and stress conditions, it can be concluded that, expected that the traits of number of spike in plant, total spikes weight, biological yield, main spike of weight, were most important and effective traits affecting yield and considering that among the genotypes, The highest diversity was observed for these traits, therefore selecting and breeding for these traits can ideally be improved the yield Genotype grouping in both conditions was conducted based on studied traits with UPGMA method, in both conditions investigated genotypes were grouped in five clusters.

Salinity is one of the most significant environmental stresses for sustainable crop production in the world's agricultural lands. Tomatoes are sensitive to salinity, and it is possible to create a tolerant genotype by evaluating the diversity among tomato genotypes under salt stress and using this diversity in tomato breeding programs. Based on this, in the current study, 22 tomato genotypes were evaluated under salt stress in a randomized complete block design with three replications. In this research, different stress tolerance indices were used to evaluate genotypes under salt stress. Stress Tolerance Index (STI), Tolerance Index (TOL), Geometric Mean Productivity (GMP), Mean Productivity (MP), Harmonic Mean (HM), Yield (Y), Yield Stability (YSI) and Stress Sensitivity (SSI) were calculated based on the total dry weight under control and stress conditions. The results of analysis of variance and mean comparison showed that there is a statistically significant difference between the studied tomato genotypes for two traits, total dry weight and total fresh weight, in two conditions of salt stress and control. These results confirmed the existence of diversity between genotypes in their morphological characteristics. The YP trait showed the highest correlation (0.9) with the MP index and the YS trait showed the highest correlation (0.91) with the HM index, and these indices are suitable for evaluating tomato genotypes under salt stress in the seedling stage. Based on bi-plot analysis, the G10 genotype was the most tolerant genotype, and after that, the G2, G22, G19 and G5 genotypes showed tolerance to salt stress. The cluster analysis divided the genotypes into three separate categories, which showed different behaviors during the transition from a non-stressed environment to a stressed environment. Based on tolerance indices and grouping methods, genotype G10 was identified as a tolerant genotype to salt stress, which can be used as a parent in hybridization and selection of tolerant genotypes.

The aim of this study was to investigate the body shape and morphological comparison between the populations of wild (marine) and farmed common carp using geometric morphology. For this purpose, 65 pieces of fish including 23 wild common carp and 42 farmed common carp were sampled. The samples were then photographed and 16 landmarks were identified on the images. Procrast analysis was used in order to remove the amorphous data from coordinate landmarks. Principal component analysis (PCA) and discriminant function analysis (DFA) tests were used. The results showed that the two populations of wild and farmed common carp are completely separated from each other using PCA and the first three components accounted for about 64.41% of the total changes. Based on DFA for morphometric characteristics, individuals were correctly placed in their original population. The results of this study showed a significant difference in body depth and body width of wild and farmed common carp using geometric morphometric method, so that the farmed common carp had deeper body (related to the displacement of landmarks 5 and 12), a wider body (related to the displacement of landmarks 5,6,10,11 and 12) and also a shorter tail stem (related to the displacement of landmarks 6, 7, 9 and 10) than wild common carp.

Gambusia holbrooki Girard, 1859 is considered as one of the non-native and invasive species in the inland waters of Iran. This species occurs in most inland basins and aquatic bodies of Iran and has even been found in brackish waters. Extensive adaptations of this species to its different habitats caused numerous changes in its biological characteristics and morphological traits. The present study was performed to investigate the sexual dimorphism of G. holbrooki in the Gamasiab River, Kermanshah Province, Iran. 59 fish specimens were collected from the river in September 2017. After taxonomic confirmation and sex determination, 29 morphological traits were measured in fish samples using a caliper and their meristic traits were recorded. In total, 37 characters (including 8 meristic traits and 29 morphometric traits) were examined. After obtaining morphological data, Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA) were utilized to compare morphological traits between male and female individuals. The results showed that the 59 specimens were comprised of 30 malea and 29 femalea. On the basis of the results, all morphological traits, except the caudal peduncle length, dorsal fin base length and a post-anal length, showed significant sexual dimorphism (p <0.05). The results of DFA and PCA analysis showed that males and females were completely different from each other in terms of morphometric traits. These findings indicate that there is a sexual dimorphism in G. holbrooki of the Gamasiab River. The sexual dimorphism observed in this fish species is due to the sexual selection and increase of reproductive success.

Sesame as one of the most important oilseed crops has high industrial, food, and medicinal potentials. Drought stress challenges sesame production, especially at the germination and seedling stages. To screen sesame genotypes for drought tolerance at the germination stage, a factorial experiment was performed in a completely randomized design with 3 replications. The studied factors included 4 drought levels induced by polyethylene glycol (concentrations of 0%, 20%, 25%, and 30%) and 15 sesame genotypes. Based on the results of ANOVA, the effect of genotype, drought, and their interaction on all studied traits including germination rate, germination speed, vigor index 1 and 2, radicle length, plumule length, and seedling fresh and dry weight was significant (P<0.01). Significant reduction (P<0.05) was observed in all levels of stress compared to the control in the studied traits. Germination rate, radicle length, and plumule length (with 10%, 17%, and 18% reduction, respectively) showed less sensitivity to drought stress at weak level (20% concentration), while the most negative effect was obtained for vigor index 2, seedling dry weight and seedling fresh weight (with 52.5%, 47.3%, and 34.4% reduction, respectively). On the other hand, the highest decrease was observed in plumule length, vigor index 1 and 2 (98%, 97%, and 96%, respectively), under severe drought (30% concentration). The calculated drought tolerance indices of each trait were used for principal component analysis and biplot visualization. Thus, genotypes were divided into 5 categories based on tolerance. Dashtestan 2 and Darab 1 genotypes were selected as the most tolerant and Qaem, Yekta, Sudan, and Kerman genotypes were selected as the most sensitive genotypes. The findings of this study can be used in future studies and breeding programs of sesame for drought tolerance.

8 sites were selected in different wetlands of Guilan province to survey the habitat preference of invasive water hyacinth (Eichhornia crassipes). At each site, a set of environmental variables (physico-chemical and structural variables in the given ecosystems) was seasonally and simultaneously sampled with 32 biological instances (16 presence samples and 16 absence samples of water hyacinth) during one year study period (2016-2017). The results of Mann-Whitney test showed that there was a significant difference between presence/absence of water hyacinth and electric conductivity, flow velocity, turbidity and bicarbonate (p < 0.01 for the first three variables and p < 0.05 for bicarbonate), while no significant difference was observed between the presence and absence of water hyacinth and other variables (p > 0.05 for all variables). Based on the results of the principal component analysis, electric conductivity, water turbidity and flow velocity were the most influential varaibles in the first to third components (more than 82 % of the total variations were related to these three components) so these variables had the major effect on the habitat suitability of water hyacinth in the wetlands. The results of generalized linear model showed that there was a significant difference between the presence and absence of water hyacinth in the sampling sites and electric conductivity, flow velocity, water turbidity and bicarbonate (p < 0.05 for bicarbonate and p < 0.01 for other 3 variables).

Water fern (Azolla filiculoides) is one of the most dangerous invasive aquatic plant species in the temperate and tropical regions of the world. 4 different sites were selected in Guilan and Mazandaran provinces to examine the habitat suitability of Azolla. 15 physical, chemical and structural variables at each site were monthly sampled simultaneously with biological data (based on 24 presence instances and 24 absence instances of Azolla) during one year (2017-2018). The results of the Mann-Whitney test showed that except water and air temperature, ammonium and turbidity (p > 0.01 for all), a significant difference was observed between the presence and absence of Azolla and the remaining variables (p < 0.01 for all). The obtained results of the principal component analysis showed that water depth, phosphate and electric conductivity were the most influential factors in the first to third components, respectively so that they had the major effect on the habitat suitability of Azolla in the sampling sites. The results of generalized linear model showed that there was a significant difference between the presence and absence of Azolla in the sampling sites and all variables used in the principal component analysis (p < 0.01).

Rice is one of the most important food crop which is the staple food for more than half of the world population. The purpose of this study was to evaluate the physical and chemical properties such as plant height, panicle length, number of effective tillers, total number of grains, number of filled grains, number of unfilled grains, 1000-grain weight, biological yield, economic yield, harvest index, chlorophyll index, growth period, total Phenol (TP), antioxidant capacity based on 2,2-Diphenyl-1-Picryl Hydrazil (DPPH) with 30 rice genotypes in a randomized complete block design in the experimental field of Amol Rice Research Institute. Results showed that Amol 1 and Bijar rice varieties had significantly higher antioxidant activities and total phenolic than the other samples examined in this study, respectively. The highest total number of grains, number of filled grains and 1000-grain weight were observed in genotype IR56. The genotypes were grouped into five clusters based on agronomic traits using UPGMA method. The highest mean of yield was related to the fourth cluster and the lowest of this attribute was related to the fifth cluster. Principal components analysis (PCA) explained 79.01% of variation and economic yield, total number of grains, and number of filled grains played the main Experimental Field role. Two principal components accounted for 43% of the raw data of the yield-related traits. The results of this research indicated that use of economic yield, total number of grains, and number of filled grains could be applied as a breeding strategy to obtain high yield rice cultivars.

6 different sites (4 sites situated in wetlands and 2 sites located in river) were selected in the Guilan and Mazandaran provinces to study the habitat suitability of Myriophyllum spicatum L. Monitoring of biotic data (36 presence and 36 absence data) was monthly carried out simultaneously with abiotic data (a set of physical, chemical and structural variables) during one year (from July 2017 to May 2018). Based on the results of Mann-Whitney, except water temperature, biological and chemical oxygen demand, ammonium and nitrite (p > 0.01), a significant difference was observed between the presence and absence of plant and the remaining of variables (p < 0.01). According to the results of principal component analysis (PCA), among 8 variables used in this method, flow velocity, total suspended solid and bicarbonate were the most important variables in the first three components, respectively so that they had the major effect on the habitat suitability of plant. According to the results of canonical correspondence analysis (CCA), the presence of plant in wetlands can be because of increasing of carbon dioxide, bicarbonate, dissolved oxygen and phosphate and the absence of plant can be attributed by increasing flow velocity, total suspended solid, electric conductivity and water depth while different seasons of year didn’t have much effect on the presence of absence of plant. Based on the results of the generalize linear model (GLM model), there was a significant difference between the presence and absence of plant and 8 variables (p < 0.01).

The current morphometric research was conducted collecting Rhamnus cathartica and Rhamnus pallasii from the natural habitats in North and West of Iran. In order to clarify the relationships in studied species and understand taxonomicall values, 58 morphological characters were employed (26 quantititative and 32 qualitative characters) using numerical taxonomy, Principal Component Analysis (CPA), and cluster analysis. In this study, leaf shape, color fruit have been found to significantly contribute to the determination of the studied species (Rhamnus pallasii & Rhamnus cathartica). The results confirmed more diversity in Rh. pallasii and three sub-species. But, in Rh. Cathartica, diversity features in the two varieties were not effective. Rh. × spathulifolia were collected from sandy hill of North of Iran which was determined by morphometric features e.g., leaflet, abaxial, adaxial leaflet trichrome, and fruit color. Overall, Rh. × spathulifolia can not be considered.

The perennial grass is one of important grassland plants, which have special importance based on their feeding production, protection, and prevention of soil erosion. One of the important genera of the wheat family is the Agropyron. The aim of this study was to evaluate genetic variability in different accessions of Agropyron based on morphological traits. In this experimental research, 31 populations belonging to the 3 species of the Agropyron were evaluated in a randomized complete block design (RCBD) with 3 replications in research farm of Agricultural Biotechnology Research Institute of Northwest and West region of Iran. The cluster analysis was performed by SPSS 17, using Euclidean space and UPGMA and the principal components analysis was performed through trait correlation coefficient matrix and Minitab 14 software. Findings: The highest value of phenotypic coefficient of variation was seen in traits, including panicle length, fresh forage yield in the first cutting, and dry matter yield in the first cutting, respectively. In the second component, seed yield and crown diameter were the most important in explaining this component. There were significant differences between different populations in terms of morphological traits, so that for these traits, the various species in this genus could be separated. From a morphological point of view, there was a great similarity between A. cristatum and A. desertorum. Different populations of A. elongatum species could be distinguished from the populations of the A. cristatum and A. desertorum in terms of morphological traits, while utilization of molecular markers is mandatory to segregate the populations of A. cristatum and A. desertorum from each other.

The effects of several factors and variables which determine forest stand structure, aren’t equal. Some of these factors, which have large effects, named as principal factors or principal components. Diagnosis and separating of this principal factors from others are very important. One of the suitable methods for determining of principal factors, is Principal Component Analysis (PCA).
In this research by PCA method, 12 forest stands of Oak (Quercus persica) and Pistachio (Pistasia atlantica), with different climatic and topographic conditions, selected and classified then by using of 31 environmental variables and structural characters, those principal factors were analysed. Results showed that variations between regions is relatively high, where 66.2 percent of total variations display in the first three axis. Regions of Cheshmehdaulat, Dalabpain and Nakhjirbala have minimum variability and regions of Melagavan, Meimeh, Nakhjirpain and Tajarian have maximum variability. In comparison to regions, we can named first axis as diameter or age axis and named second axis as almost species diversity. Variation between variables is too relatively high, where 61.3 percent of total variations display in the first three axis. Percent of health trunk, species diversity, tree density, number of dry branches, mean diameter at breast height and total canopy have larger variations in comparison to other variables.

The aim of current study is effective water quality parameters of Aras River using principal component analysis (PCA) from 2015 to 2016. Samples were collected at four seasons and analyzed using standard methods (titration and spectrophotometer instruments). In this study, thirteen parameters such as water temperature, DO, BOD5, COD, TDS, Turbidity, TA, CO2, pH, DIP, NH4/N, NO2/N and NO3/Nwere analyzed. Results showed that based on PCA test, six parameters were involved in the first component (with variance of 34%) and DO and COD contained high loading factor which there were selected as the main parameters of the first component. Also, in the second component (with 23% variance), the parameters of carbon dioxide and pH, in the third component (with 16% variance), the parameters of BOD5 and NO2- and in the fourth component (with 12% variance), the TA were contributed. This study showed that the PCA test is a suitable and effective method for determining the effective water quality parameters and also dominance source of various contaminations.