Truss Measurements Research Articles

Morphological variation in Schizothorax oconnori, Schizothorax waltoni (Teleostei: Cyprinidae: Schizothoracinae), and their natural hybrids from the middle Yarlung Zangbo River, Tibet.

The morphological variation in Schizothorax oconnori, Schizothorax waltoni, and their natural hybrids was examined using conventional and image-based analysis approaches. In total, 38 specimens of S. oconnori, 35 of S. waltoni, and 37 natural hybrids were collected from the Shigatse to the Lhasa section of the Yarlung Zangbo River during June and July 2021. A total of 21 morphometric, 4 meristic, and 27 truss variables were employed for the classification of S. oconnori, S. waltoni, and natural hybrids. Principal component analysis (PCA) and factor analysis (FA), as well as discriminant function analysis (DFA) and cluster analysis (CA), were conducted to identify differences based on traditional and truss measurements. Four principal components explained 75.92% of the variation among the morphometric characters, while five principal components accounted for 79.69% of the variation among the truss distances. FA results showed that factor 1 was associated with head shape, and factor 2 was associated with fins based on morphometric characters. Among the truss characters, factor 1 was related to head shape, and factor 2 was related to chest shape. In DFA, morphometric measurements achieved higher accuracy (100%) compared to truss distances (94.55%). The head morphology of hybrids exhibited intermediate traits between S. oconnori and S. waltoni. Both morphometry-based and truss-based clustering indicated that the morphology of natural hybrids leaned toward S. oconnori. In conclusion, the combination of morphometric and truss analysis is beneficial for classifying S. oconnori, S. waltoni, and their natural hybrids. The presence of natural hybrids could be considered an evolutionary response to the differentiation of nutritional and spatial niches in the middle Yarlung Zangbo River.

Assessment of Morphometric Variations Among the Populations of Asian Sheat Catfish <i>Wallago attu</i> (Siluridae) from Five Indian Rivers

Morphological variations of the Asian sheat catfish, Wallago attu (Bloch and Schneider, 1801) sampled from the rivers Gomti, Ganga, Yamuna at Lucknow, Kanpur and Agra districts in Northern India, river Hooghly at Kolkata in Eastern India and river Pampa at Kerala in Southern India were analyzed in the present study. Images of 261 specimens of W. attu were taken without harming the fish to evaluate the morphometric variation using 8 digitized homologous landmarks for truss analysis and geometric morphometrics. Size corrected morphometric variables were analyzed using analysis of variance (ANOVA), multivariate analysis of variance (MANOVA), principal component analysis (PCA) and discriminant function analysis (DFA). Coefficients of all PCs were positively and negatively correlated to 31 significant (p 0.001) truss measurements due to variations in size and shape. Morphometric measurements lying in the head region such as head length (HL), eye diameter (ED), inter-orbital length (IOL) and snout length (SNL) contributed most to differentiate the populations in truss analysis. The ED, HL, SNL and IOL of Yamuna fish was significantly (p 0.001) smaller than the other fish populations. This could be attributed to the heavy pollution load in the Yamuna River and differences in the feeding regimes of fish. PCs and relative warps depicted differences in geometric analysis because of body shape variations among different river populations. The scatter plot in DFA revealed the presence of three distant and different phenotypic groups of W. attu among five wild river populations of fish with 70.5 and 83.9% of correct classification of fish into their original groups in truss and geometric analysis respectively. A single homogenous stock of fish was found to be in the rivers Gomti, Ganga and Hooghly because of a high level of intermixing (maximum misclassification) among the three river populations, whereas Yamuna and Pampa populations were two non-overlapping isolated groups due to negligible intermixing. These variations in the present study might be the effect of geographical isolation and river fragmentation due to the change in habitat that restricts fish movements. This is the first report on the morphometric assessment of W. attu that provides base line data for further confirmatory stock studies that would be useful for conservation and sustainable management of this vulnerable fish.

Stock identification of Congaturi halfbeak (Hyporhamphus limbatus): insight into conventional and truss-based morphometrics

BackgroundWild fish stocks continuously decline in Bangladeshi rivers and oxbow lakes. Small indigenous fish species management solely depends on their population status and conservation. This study aimed to determine the population status of Hyporhamphus limbatus, in Southwestern Bangladesh using conventional and truss morphological characteristics.ResultsA total of 174 fish samples were procured from monsoon season i.e., May to August 2018 the Bhairab River, BR; Kopotakkho River, KR; and Baluhar Baor, BB in Bangladesh. Five meristics, six conventional and twelve truss-based morphometric characters, were considered for stock identification. The Kruskal–Wallis test helped to analyze the meristic characters, while ANOVA, principal component analysis (PCA), discriminant function analysis (DFA), correct classification analysis using DFA, and a UPGMA dendrogram formation were used to investigate the conventional and truss measurements. By the Kruskal–Wallis test, no meristic characters showed significant differences across different populations. Eleven of the 18 morphometric measurements showed significant differences among three populations through the univariate ANOVA. PCA specified the population structure variations and explained 67.438% of the total variance. The first and second discrimination functions accounted for 78.3% and 21.7%, representing 100% of the group variability. Similarly, 85.6% of the grouped cases and 77.6% of cross-validated grouped cases were initially effectively represented by their correct number of individuals. A dendrogram based on morphometric (conventional and truss) displayed three stocks grouped into two clusters, with BR forming a distinct cluster, while KR and BB creating a shared cluster.ConclusionIn conclusion, such morphological differences are most likely due to their distinctive ancestral origins. This study presents novel reports on the stock assessment of H. limbatus in their natural ecosystem. Furthermore, molecular research and an evaluation of the environmental impact on H. limbatus populations in Bangladesh are strongly recommended.

Morphological discrimination of tiger shrimp Penaeus monodon between female and male based on traditional and truss morphometric analyses

The morphological difference of tiger shrimp, Penaeus monodon from Aceh waters is limited to explore for female and male discrimination using morphometric analyses. The study aimed to evaluate the morphological characters between female and male tiger shrimp using traditional and truss measurements. A total of 57 samples (39 females and 18 males) were analysed using 9 characters for traditional morphometric and 40 characters for truss morphometric. Multivariate analyses were applied to reveal the morphometric variation between male and female populations. The result of principal component analysis indicated that 4 characters, i.e: carapace length (CL), carapace width (CW), rostrum length (RL), and sixth segment length (SL6), were significantly different (P<0.05), while three truss morphological characters, i.e: distance between anterior and posterior carapace, distance between ventral posterior sixth segment to telson end, and distance between anterior and posterior second segment, were significantly discriminated (P<0.05) between female and male of tiger shrimp. Overall, 94.9% of the male and 88.9% of the female individuals were assigned to their native populations using traditional morphometric analysis, while truss morphometric was 87.2% and 88.9%, respectively. The individual proportion of 93.0% was properly classified into their original population group for traditional morphometric and 87.7% for truss morphometric characters.

Phenotypic variation of Chitala chitala (Hamilton, 1822) from Indian rivers using truss network and geometric morphometrics.

Chitala chitala (Hamilton, 1822) is an economically important food fish species occurring throughout Indian rivers, which also has ornamental value. This study focuses on morphological variations in C. chitala from seven river basins across India namely; Son, Tons, Ken, Brahmaputra, Ganga, Gomti and Gandak. A truss network was constructed by interconnecting nine landmarks to generate 36 morphometric variables extracted from digital images of specimens sampled from the study locations. Transformed truss measurements were subjected to principal component analysis (PCA), canonical discriminant function analysis (CDFA) and discriminant analyses of principal components (DAPC). DAPC function coefficients performed much better in capturing the variation pattern and discrimination between the rivers which was not achieved using CDFA. Eight truss variables were identified with significant and highest loading for truss variables on principal components and coefficients on discriminant function from DAPC contributing to maximum variation between the rivers. Performance graph and functional distribution of identified truss variables clearly indicated distinction between the rivers. Thin plate spline analysis and procrustes shape analysis further showed the variation in morphology between specimens across the rivers. The significant parameters differentiating specimens from different rivers were linked to dorsal fin origin, the base of the pectoral fin and the perpendicular point on the anal fin from the dorsal fin origin. Variation in the hydrodynamics of the rivers studied might be possibly affecting the fin kinematics and consequently leading to adaption seen as phenotypic variation in C. chitala. The results showcased in the present study shall help in better understanding of intra-specific diversity which is significant for management and conservation of a species.

Stock Structure Analysis of the Endangered Queen Loach, Botia dario (Hamilton 1822) from Five Rivers of Northern Bangladesh by Using Morphometrics: Implications for Conservation

Identifying stock is key to sustainable fisheries management and conservation. Using traditional morphometrics (TMR) and image-based truss network analysis (ITNA), we evaluated the stock structure of the endangered queen loach, Botia dario. The study was carried out in the following five stocks in Bangladesh’s northern rivers: the Atrai, Dhorala, Danu, Jamuna, and Padma. The inventory regarding stock structure was investigated using a total of nine traditional morphometrics, 11 ratios, and 23 truss measurements for each individual. To generate 23 ITNA, 12 landmarks were used. To assess variations among the stocks, a principal component analysis (PCA), factor analysis (FA), canonical variate analysis (CVA), and cluster analysis (CA) were performed. Six principal components explained 91.50% of the variation in TMR, while seven principal components explained 73.425% of the variation in ITNA. CVA, using traditional methods and ratios were correctly classified as 65.0%, 42.0%, 64.2%, 89.3%, and 77.5% for Danu, Padma, Jamuna, Dhorala, and Atrai River stocks, respectively, based on original grouped classes. CVA using ITNA was correctly classified as 90.0%, 80.0%, 77.4%, 94.6%, and 98.6% for Danu, Padma, Jamuna, Dhorala, and Atrai River stocks, respectively, based on original grouped classes. CVA analysis based on TMR and ITNA showed that cannonical variates (CV1 to CV3) are related to the whole-body shape. Both TMR and ITNA formed two clusters. In the first cluster, the Jamuna and Atrai River stocks combinedly formed a separate stock based on (TMR). In ITNA, the Dhorala and Atrai River formed as separate stocks from the other four stocks. According to this study, combining TMR and ITNA analysis aids in the differentiation of various B. dario stocks. The stock separation of this species was supposed to be geographic disconnection, waterway nature, and temperature variations. The B. dario stocks are heavily exploited and the species is an ideal nominee for species variation to boost the aquaculture yield. Within-stock distinctions were revealed in this study, necessitating the identification of gene pools and molecular studies to achieve a deeper understanding of the stocks. Through a more scientific approach, this stock structure study may aid in the development of conservation programs for this endangered species.

Effect of formalin preservation on studies on morphology and condition factor of the freshwater shark Wallago attu (Bloch and Schneider, 1801) using truss network system

The study was aimed to evaluate the effect of formalin preservatiion on the shape, size and condition factor of the freshwater silurid catfish Wallago attu (Bloch and Schneider, 1801) using length-weight relationship (LWR), condition factor and truss analysis. A total of 50 specimens of the fish were procured from the river Ganga at Kanpur region. The fresh and formalin preserved fish were measured for total length, standard length and body weight. Results of LWR revealed that the fresh and preserved fish followed different growth pattern and cube law. High values of r2 were obtained for the relationship between length and weight of the fish before and after preservation of the fish in formalin. Decrease in length and an increase in weight was observed in the preserved specimens of the fish due to the effect of formalin but were not statistically significant. The mean condition factor (K) showed significant (p<0.05) change in the fish after preservation. The univariate and multivariate analysis of truss measurements, two partially overlapping different convex hulls of the scatter plot of PC1 on PC2 and canonical discriminant functions showed highly significant morphometric heterogeneity between the specimens of fresh and preserved fish. The results of the present study suggest that fresh specimens of the fish should be used in research studies based on weight and linear body measurements of the fish. Keywords: Condition Factor, Formalin, Length-weight relationship, Truss network system

Stock structure analysis of the endemic fish, Barbodes carnaticus (Jerdon 1849), for conservation in a biodiversity hotspot.

The population structure of Barbodes carnaticus species was studied using conventional (based on body morphometrics and meristic) and image-based analysis (truss network system) methods. The study was carried out with four stocks, namely Karnataka (KA) and Tamil Nadu (TN) stocks from the River Cauvery, Kerala (KE) stock from the River Chalakudy and farm-reared stock (CI) from Central Institute of Freshwater Aquaculture, Bangalore. A total of 27 morphometric, 9 meristic and 30 truss measurements were used in the study for the stock structure. Fifteen landmarks were used to generate 30 truss distance measurements. The principal component analysis (PCA), factor analysis (FA), discriminant function analysis (DFA) and cluster analysis (CA) were deployed to determine the variation using both the conventional and truss variables. Variations (86.9%) among the morphometric characters were explained by five principal components, while four principal components explain 96.01% of the variation among the truss distances. DFA using conventional method correctly classified 100% of the original grouped classes of the KA, KE and CI and 93.8% of TN stocks. The DFA employed with truss distance was classified into the stocks CI, KA, KE and TN, and the values are 100, 89.1, 8.6 and 6.1%, respectively. Factor analysis based on truss morphometry showed that factor one is related to body shape and factor two is related to head shape. Two clusters were identified in both the conventional and the truss distance analysis. Truss distance-based cluster showed that the KE and CI stocks are similar compared to the TN stock. In contrary, morphometry-based cluster showed the KE and TN stocks are similar compared to CI stock. The multivariate analysis showed that the farm-reared stock (CI) is different from the wild stocks (KA, KE and TN). This study explained that the combination of the conventional and image-based truss network analysis helps to discriminate various stocks of B. carnaticus. Based on the PCA, bilinear data models were generated using R 3.5.3 software for predicting the stock of each individual. Stock discrimination of this species was mainly due to the geographic isolation, river ecology and temperature variations. The stocks of B. carnaticus are highly exploited from the studied rivers, and the species is an important candidate for species diversification to enhance aquaculture production. Within stock variations are found to be minimum in the present morphometric study, hence the gene pool identification and marker study are required for better understanding of the stocks. This stock structure study may help to develop conservation programmes for this endemic species through a more scientific approach.

Differentiation of endangered butter catfish, Ompok bimaculatus populations along the selected habitats of South-western Bangladesh: Evidence from morphological characters

The intraspecific morphological variations of the butter catfish, Ompok bimaculatus has been assessed from two fish farms viz., Chanchra Fish Farm, Jashore (CFFJ) and Fish Seed Complex, Khulna (FSCK) and two natural wetlands viz., Bohni beel, Gopalganj (BBG); Dakatia beel, Khulna (DBK) in the south-western part of Bangladesh. A total number of 80 samples were collected comprising 20 individuals from each sampling location. Five meristic characters, 18 morphometric characters and 21 truss-based morphometric characters were measured respectively. Meristic, morphometric and truss-based morphometric characters were exposed to one-way analysis of variance followed by Tukey-HSD post-hoc test at 5% significance level. Significant differences were observed in two meristic characters viz., CFR and PevFR, and five morphometric and four truss morphometric characters. However, morphometric and truss measurements showed highly intermingled among four populations in discriminant functions (DFs) analysis and discriminant space as well. DFs showed that 6-7, PrDL, HL, PSDL, 1-2, 4-6, FL, ED, 3-9, 5-6, SnL and 4-5 characters contributed 62.8% in first DF, while 2-9, HD, 1-9, 2-3, 2-6, 3-6, 3-4, LAB, 3-8, 9-10, IO and MXBLR characters contributed 20.6% in second DF, and the remaining characters contributed 16.6% in third DF. In cluster analysis, two distinct clusters were made, where BBG demonstrated a solitary group, and FSCK and CFFJ jointly shaped alternative clusters, while the DBK population found a subgroup with CFFJ. These results postulate the occurrence of intermingling populations of this species from four aquatic habitats. These morphological discrepancies play an important role in establishing proper decisions in order to achieve appropriate management and conservation as well as mass seed production for their future sustainability.

Intraspecific phenotype variations in olive barb Systomus sarana (Hamilton, 1822) population from different rivers is possibly linked to locomotive adaptations in caudal fin

Systomus sarana (Hamilton, 1822) [D1] is an economically important food fish species occurring throughout Indian rivers, which also has ornamental value. This study focused on morphological variations in S. sarana from five river basins across India, viz., Godavari, Mahanadi, Krishna, Middle Ganga and Lower Ganga. A truss network was constructed by interconnecting 12 landmarks to generate 65 morphometric variables extracted from digital images of specimens sampled from the study locations. Transformed truss measurements were subjected to Principal component analysis (PCA), Canonical discriminant function analysis (CDFA), Box plot and Thin plate spline (TPS) analyses. PCA identified eight truss variables with significant loadings, while CDFA designated two truss variables with potential for explaining discrimination between populations. Anterior attachment of dorsal membrane from caudal fin was identified to be the most important variable that presented variations across the river basins studied. Discriminant analysis correctly classified 70.5% of the specimens into their original populations. Thin plate spline for morphometric shape variation analysis indicated highest specimen-shape variations (warping) in Mahanadi basin. TPS-principal strain ratio on principal components (PC-1, PC-2) further revealed significant divergence among the populations in five river basins studied. Results of the study revealed variation in stocks of the species, on the basis of shape morphometry. The four significant parameters, differentiating specimens from different basins, were linked to caudal fin origin at dorsal side and the centre and possibly indicate plasticity in response to locomotive adaptations.

MORPHOLOGICAL VARIATION BETWEEN HATCHERY AND WILD ANABAS TESTUDINEUS, BASED ON TRUSS NETWORK ANALYSIS

Several body measurement methods used to identify stock have recently been criticized because of inherent biases and weaknesses. As an alternative, a new system of morphometric measurement called the truss network has been increasingly used for stock identification. Therefore, the morphometric differentiations between wild and captive populations of Anabas testudineus were carried out throughout this study using a truss network. Truss measurements based on anchored at ten homologous landmarks with 19 distances of 120 specimens were measured. Discriminant analysis was performed to investigate distinctions and patterns of morphological variations between wild and captive populations of Anabas testudineus. The findings support the use of the truss network to study the morphological variation among populations as it provides interesting perspectives for the study of biodiversity patterns.

Land-Mark based morphometric and meristic variations in two congeneric hilsha population, Tenualosa ilisha and Tenualosa toli from Bangladesh water bodies

The morphometric characters are effectively used for the better differentiation among the fish population and sustainable management. The appraisal of the natural population stock and morphological variation within and between two hilsha species (Tenualosa ilisha and Tenualosa toli) from three different habitat (Coastal, riverine and marine) of Bangladesh, were investigated by applying the land mark based morphometric and meristic variation measurement methods. All data were adjusted and Univariate ANOVA, where discriminant function analysis (DFA) and principal component analysis (PCA) exhibited the divergences in eight morphometric measurements and eight truss network measurements among the three stocks of T. ilisha. The 1st DFA accounted for 89.8% &amp; 87.4% and the second DFA resolved 10.2% and 12.6%, respectively in morphometric characteristics variation among the group studied. Scattered plotting from PCA and dendogram from cluster analysis (CA) revealed that, the river habitants were morphologically different from the coastal and marine population. Twelve of fifteen morphometric measurements and thirteen of fourteen truss network measurements showed significant differences between T. ilisha and T. toil with significant variation in meristic characters. PCA revealed 89.23% and 88.29% in case of morphometric and truss measurement respectively confirmed high degree of variations in morphological characteristics between two species. Overall, our results based on morphometrics with truss measurements together provide useful information about the morphological differentiation which will be helpful for sustainable exploration and effective management for these two species.&#x0D; Asian J. Med. Biol. Res. June 2020, 6(2): 265-282

Application of multifactorial discriminant analysis in the morphostructural differentiation of wild and cultured populations of Vieja Azul (Andinoacararivulatus)

To better determine the ecological variation (body shape and structure) of the Vieja Azul (Andinoacara rivulatus; syn.: Aequidens rivulatus) in northwest Ecuador (Los Rios Province), 300 specimens of both sexes (150 male and 150 female) were collected from 3 different locations, one from a wild production system and two from fish farm populations in the Quevedo River. Twelve meristic, 26 traditional morphometric, and 32 truss measurements, among 25 anatomical landmarks, were determined. The body weight (BW), total length (TL), eye diameter (ED), dorsal fin ray length (DFRL), and body perimeter 3 (P3) showed significant differences (P < 0.05) between production systems, and sex had significant influence on preanal length (Pre-AL), P3, and body width 2 (LC2). Females showed higher mean values than males in all measurements, except for BW. The Fulton factor differed for both factors considered. The canonical discriminant analysis revealed a percentage of correct assignment of 64.42% for the dataset, 85% and 60.9% for cultured and wild females, and 62.1% and 56.3% for wild and cultured males, respectively, as well as morphometric variation between groups. Results could be attributed to environmental conditions (habitat, temperature, and food). The Mahalanobis test showed greater distances among females than among males. In conclusion, this study provides valuable morphological information on the shape and structure of Andinoacara rivulatus that can be used to characterize and quantify the changes that occur as a consequence of adaptation to a different habitat. The authors hope that the information obtained from the present study will be helpful for fisheries, biologists, and taxonomists.

Phenotypic divergence and molecular characterization of two sympatric species of genusBarilius(Hamilton) from the River Chenab of Western Himalaya

Barilius bendelisis and Barilius vagra inhabit mostly in the spring-fed streams of Indian Himalaya and constitute an important portion of protein diet of the rural human population residing near the stream banks. In spite of large aquaculture importance of this genus very less morphometric and molecular studies have been conducted. This study addresses morphometric and molecular characterization of B. bendelisis and B. vagra by using truss analysis and mitochondrial COI gene. A total of 293 samples of Barilius bendelisis and 127 samples of Barilius vagra were collected from three different sites of Chenab river basin from March 2015 to April 2017. 14 landmarks were used to measure 90 truss measurements from digital images of specimens using network of three softwares, tpsUtil, tpsDig2 and PAST. A total of 89 distance variables exhibited significant differences among the populations. The principal component analysis generated ten components explaining 89.164% of total variance among six populations of B. bendelisis and B. vagra. 89.0% of individuals of B. bendelisis and B. vagra were classified into their original groups. The Phylogenetic analysis with other published COI sequences revealed distinct nature of these two species. The study may aid in taxonomic identification and phenotypic divergence which will be helpful in proper conservation and management of these species of hill trout in India.

Meristic and Morphometric Variations of Barred Spiny EEL Macrognathus pancalus Populations from Bangladeshi Freshwaters: An Insight Into Landmark-Based Truss Network System

Abstract The present research focuses to examine the meristic and landmark-based morphometric variations of barred spiny eel Macrognathus pancalus from four populations namely Dhakuria beel, Jessore (DBJ); Bohnni boar, Gopalgonj (BBG); the Arial kha river, Madaripur (AKRM) and the Nabaganga river, Jhenidah (NRJ) in Bangladeshi freshwaters. Six meristic counts were compared among four populations and significant differences were observed in number of caudal fin rays and number of pelvic fin rays in all meristic characters. The truss protocol was used in the present study based on six general morphometrics and fifteen truss measurements. Univariate statistics showed that five (standard length (SL), upper jaw length (UJL), lower jaw length (LJL), head depth (HD) and inter orbital (IO)) of six morphometric and eleven truss networks (viz. 2-3, 3-4, 5-6, 6-7, 7-8, 1-8, 2-8, 3-8, 3-7, 4-7 and 5-7) among fifteen truss measurements differed significantly. Cannonical discriminate function analyses were conducted among samples and the populations were fully intermingled. Pooled within-group correlation showed morphometric and landmark measurements; the first discriminant function (DF) accounted for 79%, the second DF accounted for 15.9% and third DF accounted for 5.1% of group variability. An euclidian dendrogram was prepared based on morphometric and truss measurements in four populations, where two clusters were mainly formed, in which first cluster formed by NRJ population was fully separated, and the second cluster was formed by two populations of AKRM and DBJ. Additionally, a subcluster BBG was formed with AKRM. On the basis of morphometric and truss measurements, 68.8%, 83.6%, 55.6% and 80% of original grouped cases were correctly classified in NRJ, AKRM, DBJ and BBG, respectively. These results specify the presence of different stocks of fish from four aquatic habitats. This study is highly significant for proper conservation and effective management of M. pancalus populations as well as for the scientific community for further research.

Morphological Differentiation Between Riverine and Lacustrine Populations of Snow Trout Schizopyge niger (Cyprinidae) from Kashmir using Truss Morphometry

Landmark-based morphometrics are examined to evaluate the population status of Schizopyge niger (Heckel, 1838) from Dal Lake and Jhelum River. A total of 180 individuals are collected from the two locations, and a truss network is constructed by interconnecting 12 landmarks to yield 30 distance variables that are extracted from digital images of specimens using tpsDig2 and PAST software. Transformed truss measurements are subjected to Principal Component Analysis (PCA), where the first component explains 78.43% of total variance, while the second and third components explain 4.62 and 2.91% of total variance respectively. The high component loadings are from the characters which mostly contribute to anterior half of body depth, middle portion of body depth, and head region. The bivariate plot of PC1 and PC2 clearly indicates the separation of the two populations. The cross validation of this analysis reveals that the percentage of correctly classified fishes is 100% both in Dal Lake as well as Jhelum River.

Landmark-based morphometric and meristic variations of freshwater garfish, Xenentodon cancila from four natural stocks of South-Western Bangladesh.

Objective:The morphometric and meristic variations of Xenentodon cancila was studied based on the landmark-based truss network system to assess their phenotypic variations among four different freshwater stocks, viz. Boluhorpur baor, Jhenaidah (BBJ) (n = 29); Bhairab River, Jashore (BRJ) (n = 34); Arial Khan River, Madaripur (AKRM) (n = 28), and Bohnni baor, Gopalganj (BBG) (n = 25) in Bangladesh.Materials and methods:Seven meristic characters were counted by using a needle. Eight morphometrics and 28 truss measurements were measured by using tpsDigV.2.1 software. In meristic characters, Kruskal–Wallis test was performed to determine any significant differences, whereas, in morphometrics and truss measurements, univariate statistics and discriminant function analyses were carried out by using SPSS 22 version.Results:Significant differences were observed in four meristic characters among seven meristic characters in the Kruskal–Wallis test. In univariate statistics, only nine characters were observed significantly different among eight morphometrics and 28 truss measurements. The contribution of three discriminant function analyses (DFA), in which first DFA showed 49.2%, second DFA showed 33%, and third DFA showed 17.8% on behalf of both morphometric and truss measurements. In discriminant space, the four stocks were clearly separated. Two clusters were formed among four stocks, where BBG formed a single cluster, whereas BBJ and BRJ aggregately formed another cluster. Additionally, AKRM formed a sub-cluster with BBJ.Conclusion:The preliminary information generated from the current study would be beneficial for further genetic studies and in the assessment of ecological impacts on X. cancila stocks in Bangladesh.

MORPHOLOGICAL VARIATIONS OF LABEO BATA POPULATIONS (TELEOSTEI: CYPRINIDAE) IN SIX RIVERS OF BANGLADESH: A LANDMARK-MORPHOMETRIC CONTRIBUTION

The morphological variations of bata, Labeo bata (Hamilton, 1822) was studied based on morphometric and landmark analysis to know the populations status in the northern and southwestern Bangladesh. Samples were collected from six river sources viz. Mathabhanga (MR); Kirtonkhola, Barisal (KR); Nabaganga, Jhenidah (NR); Padma (PdR); Jamuna (JR) and Punorvoba, Dinajpur (PR). Univariate statistics among 22 truss measurements and 15 morphometric characters revealed a significant inter stock variation ( P <0.05, P <0.01, P <0.001) among all the samples. The first, second, third, fourth and fifth discrimination function (DF) accounted for 78.5, 9.6, 7.9, 0.0 and 4% respectively in group variability, conferring 100% of total along group variability. Two clusters were formed in Euclidean dendrogram, in which 1st cluster formed by Kirtonkhola river population and 2nd cluster formed by remaining population along with the five sub clusters (MR, NR, PdR, JR and PR). These analyses supported that ‘truss network’ is an effective tool for determining the population status and baseline information of L. bata .

Morphological analysis of Trichomycterus areolatus Valenciennes, 1846 from southern Chilean rivers using a truss-based system (Siluriformes, Trichomycteridae).

Trichomycterus areolatus Valenciennes, 1846 is a small endemic catfish inhabiting the Andean river basins of Chile. In this study, the morphological variability of three T. areolatus populations, collected in two river basins from southern Chile, was assessed with multivariate analyses, including principal component analysis (PCA) and discriminant function analysis (DFA). It is hypothesized that populations must segregate morphologically from each other based on the river basin that they were sampled from, since each basin presents relatively particular hydrological characteristics. Significant morphological differences among the three populations were found with PCA (ANOSIM test, r = 0.552, p < 0.0001) and DFA (Wilks’s λ = 0.036, p < 0.01). PCA accounted for a total variation of 56.16% by the first two principal components. The first Principal Component (PC1) and PC2 explained 34.72 and 21.44% of the total variation, respectively. The scatter-plot of the first two discriminant functions (DF1 on DF2) also validated the existence of three different populations. In group classification using DFA, 93.3% of the specimens were correctly-classified into their original populations. Of the total of 22 transformed truss measurements, 17 exhibited highly significant (p < 0.01) differences among populations. The data support the existence of T. areolatus morphological variation across different rivers in southern Chile, likely reflecting the geographic isolation underlying population structure of the species.

Morphological Characterization of Two Fresh Water Eels Monopterus cuchia (Hamilton, 1822) and Ophisternon bengalense (McClelland, 1844)

Morphometric and meristic characters and truss measurements of 32 Monopterus cuchia, and of 17 Ophisternon bengalense were compared to know the population status of two fresh water eels of Bangladesh. The mean numbers of line below head were significantly different between two species. Significant differences were observed in 11 morphometric characters: Pre dorsal length (PDL), Post dorsal length (PoDL), Post anal length (PoAL), Head length (HL), Snout length (SnL), Upper jaw length (UJL), Lower jaw length (LJL), Head width (HW), Pre orbital length (PrOrL), Least body diameter (LBD) and Highest body diameter (HBD) and one truss measurement (3-5) between two species in varying degrees. For both morphometric and landmark measurements, the first and second DF (discriminant function) accounted 64.8% and 33.2% of among group variability, explaining 98% of total group variability. M. cuchia collected from Mymensingh and from Dinajpur constructed one sub-cluster and O. bengalense collected from Sathkhira and from Bagerhat constructed another sub-cluster based on the Distance of squared Euclidean dissimilarity. A correct classification of individuals into their original population from leave-one-out-classification varied between 93.3% and 94.1% by discriminant analysis. The results of the present study suggested that there was limited intermingling among populations and the populations of the species were separated from one another.J. Environ. Sci. &amp; Natural Resources, 9(1): 127-137 2016