Iranian Scientific Fisheries Journal

fa مقاله علمی – پژوهشی:‌ ویژگی‌های ریختی گونه مرواریدماهی قفقاز (Alburnus hohenackeri) در حوضه آبریز هریرود Morphological characteristics of the North Caucasian bleak species (Alburnus hohenackeri) in the Harirud basin بيوسيستماتيك آبزيان بيوسيستماتيك آبزيان پژوهشي Research این پژوهش با هدف بررسی و مقایسه ویژگی‌های ریختی جمعیت‌های مرواریدماهی (Alburnus hohenackeri) در حوضه هری، با استفاده از روش ریخت‌سنجی هندسی صورت گرفت. برای این منظور، 141 نمونه از رودخانه‌های مختلف حوضه هری شامل کانال هریرود 1، کانال هریرود 2 و هریرود جمع‌آوری شدند. تصاویر جانبی سمت چپ این نمونه‌ها تهیه شده و سپس 13 نقطه لندمارک با استفاده از نرم‌افزار tpsDig2 رقومی‌سازی گردید. پس از انجام واکاوی پروکراست برای حذف اثر اندازه، داده‌های شکل با سه روش آماری چندمتغیره شامل: (۱) تحلیل مؤلفه‌های اصلی (PCA) برای بررسی کلی تغییرپذیری، (۲) تحلیل متغیرهای کانونی (CVA) برای تفکیک بین‌گروهی و (۳) تحلیل خوشه‌ای با الگوریتم UPGMA برای طبقه‌بندی جمعیت‌ها، مورد تحلیل قرار گرفتند. نتایج تحلیل مؤلفه‌های اصلی (PCA) نشان‌دهنده همپوشانی قابل‌توجه بین جمعیت‌ها بود که حاکی از عدم تفاوت معنادار ریختی بین آنهاست. اما در تحلیل متغیرهای کانونی، جدایی کامل بین سه جمعیت مشاهده شد و نتایج تحلیل خوشه‌ای نیز نشان داد که جمعیت کانال هریرود 2 از دو جمعیت دیگر متمایز است. این تفاوت نتایج احتمالاً ناشی از تفاوت روش‌های آماری به‌کاررفته است به‌طوری‌که تحلیل متغیرهای کانونی تمرکز بیشتری بر تفکیک جمعیت‌ها و تغییرات بین گروه‌ها دارد درحالی‌که تحلیل مؤلفه‌های اصلی عمدتاً واریانس کلی داده‌ها را بررسی می‌کند. این نتایج نشان می‌دهند که عوامل محیطی ممکن است نقش مهمی در ایجاد تفاوت‌های ریختی بین جمعیت‌ها ایفاء کنند. نتایج این پژوهش می‌تواند به عنوان داده پایه در برنامه‌ریزی‌های مدیریتی و حفاظتی به‌ویژه در زمینه حفظ تنوع زیستی، جلوگیری از کاهش ذخایر و تدوین استراتژی‌های بهره‌برداری پایدار مورد استفاده قرار گیرد. همچنین شناسایی تفاوت‌های ریختی بین جمعیت‌ها می‌تواند به مطالعات بعدی در زمینه ارتباط این تفاوت‌ها با عوامل محیطی کمک کند. Introduction Fish biodiversity is fundamental to the stability and functionality of aquatic ecosystems. A detailed understanding of fish species, particularly native taxa, is essential for effective resource management and conservation planning. Alburnus hohenackeri, a native species of the Harirud River basin in the family Leuciscidae, typically inhabits vegetated riverine areas and freshwater lakes, but it can also tolerate slightly brackish waters. Although naturally distributed across the Caspian Sea basin, this species has been unintentionally introduced into several other aquatic systems, including Zarivar, Maravin, Hamun, Sistan, and Harirud (Naderi and Abdoli, 2004). Given the ecological heterogeneity of these habitats, investigating morphological variation among different populations is particularly important. Geometric morphometrics, which employs anatomical landmark points, provides a robust tool for analyzing shape variation and exploring habitat influences, phenotypic plasticity, and species identification (Park et al., 2013). Previous studies in Iran have revealed substantial morphological diversity among various fish species. Gholami and Keyvani (2024) examined 487 specimens of Alburnus hohenackeri from 12 rivers using 13 anatomical landmarks and reported pronounced differences in body shape, head structure, mouth position, and fin placement, particularly in populations from the Aras River. Comparable patterns of morphological variation have been documented in Alburnus mossulensis (Keivany et al., 2016) and Capoeta damascina (Razavipoor et al., 2014). Despite its ecological importance, however, the morphological characteristics of A. hohenackeri populations in the Harirud basin remain poorly understood. The present study therefore aims to investigate and compare the morphological features of these populations using geometric morphometric techniques. The results will provide critical baseline data to inform conservation initiatives, support sustainable resource management, and guide strategies for preserving freshwater biodiversity. Methodology This study employed geometric morphometric techniques to examine morphological variation among Alburnus hohenackeri populations in the Harirud River basin, focusing on three sites: Harirud Canal 1, Harirud Canal 2, and the Harirud River. A total of 141 specimens were obtained from the reference collection of the Ichthyology Museum at Isfahan University of Technology. The samples were originally collected in 2009 from the three sampling stations, while laboratory procedures and data analysis were conducted in 2019. Specimens were captured using beach seines and electrofishing, fixed in 10% buffered formalin, and preserved in 70% ethanol for long-term storage. For morphometric analysis, the left lateral side of each specimen was photographed, and 13 anatomical landmarks were digitized using TpsDig2 software. These landmarks were chosen based on distinct anatomical reference points covering the head, fins, and caudal peduncle, following the standard protocol of Cavalcanti et al. (1999). The digitized coordinates were aligned and scaled using Procrustes superimposition, and multivariate statistical analyses—including Principal Component Analysis (PCA), Canonical Variate Analysis (CVA), and Cluster Analysis—were conducted to identify morphological similarities and differences among populations. All analyses were performed using PAST and MorphoJ software. Results Principal Component Analysis (PCA) indicated that the first five principal components accounted for 73.52% of the total shape variation among Alburnus hohenackeri populations. These components were identified as the primary factors differentiating population structures. The distribution of individuals along the first two principal components suggested some population grouping; however, considerable overlap among populations was observed, indicating relatively subtle morphological differentiation. Examination of body shape variation along the principal components revealed notable changes in several anatomical regions. Along PC1, variations were observed in the positions of the mouth, eye, operculum, pectoral, dorsal, pelvic, and anal fins, as well as in body height and the caudal peduncle. PC2 showed similar but less pronounced changes, primarily affecting eye position, head structure, fins, and the caudal peduncle. Canonical Variate Analysis (CVA) revealed significant morphological differences among the three populations, with clear separation and no overlap between Harirud Canal 1, Harirud Canal 2, and Harirud River groups. Shape changes along CV1 were mainly associated with posterior displacement of the mouth, shifts in eye and operculum positions, and fin attachment points. CV2 reflected variations primarily in mouth position, eye socket, dorsal fin insertion, and caudal peduncle landmarks. Cluster analysis corroborated these results, showing that the Harirud Canal 2 population was distinctly separated from the other two groups, indicating a higher degree of morphological divergence. In contrast, Harirud Canal 1 and Harirud River populations formed sister groups, displaying the closest morphological similarity. Discussion and conclusion Morphological variation among fish populations often reflects adaptations to diverse environmental conditions, including water flow, substrate type, vegetation cover, prey availability, and predation pressure (Mouludi-Saleh et al., 2020). In this study, significant morphological differences were observed among Alburnus hohenackeri populations in the Harirud River basin, particularly between the Harirud Canal 2 population and those from Harirud Canal 1 and the Harirud River. While PCA indicated some degree of overlap among populations, Canonical Variate Analysis (CVA) revealed clear separation, suggesting that environmental factors, geographic isolation, or a combination of both contribute to shape divergence. Cluster analysis further supported these findings, placing Harirud Canal 2 in a distinct group, whereas Harirud Canal 1 and Harirud River populations exhibited closer morphological similarity, possibly reflecting geographic proximity or shared ecological conditions. Differences in body depth, fin placement, caudal peduncle shape, and head dimensions likely represent ecological adaptations. Variations in swimming patterns, feeding behavior, hydrodynamic constraints, and predator-prey interactions may account for the observed morphological differences (Langerhans et al., 2003; Andersson et al., 2006). Previous studies on A. hohenackeri and other Cyprinid species in Iran have similarly highlighted environmental heterogeneity and geographic isolation as key drivers of morphological differentiation (Banimasani et al., 2019; Gholami and Keyvani, 2024). Given the ecological significance of A. hohenackeri and the role of morphology in survival and resource utilization, these findings provide important insights into population-level diversity and adaptation. Future studies should integrate detailed ecological measurements—such as water flow, vegetation cover, and predator-prey dynamics—with genetic analyses to elucidate the mechanisms driving morphological variation. Such information will be valuable for conservation planning and sustainable management of A. hohenackeri populations, particularly in regions facing environmental stress and biodiversity loss. Conflict of interest The authors declare that there is no conflict of interest regarding the publication of this paper. Acknowledgment The authors would like to sincerely thank the Ichthyology Museum of Isfahan University of Technology for providing access to specimens and facilities that made this research possible. مرواریدماهی قفقاز, ریخت‌سنجی هندسی, تحلیل مولفه‌های اصلی, تحلیل متغیرهای کانونی, واکاوی پروکراست Alburnus hohenackeri, geometric morphometry, Principal Component Analysis, Canonical Variate Analysis, Procrustes analysis 81 92 http://isfj.ir/browse.php?a_code=A-10-2974-1&slc_lang=fa&sid=1 Soroor Gholami سرور غلامی s_gholami@na.iut.ac.ir 100319475328460040986 100319475328460040986 Yes Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. دانشکده منابع طبیعی، دانشگاه صنعتی اصفهان، اصفهان، ایران Yazdan Keyvani یزدان کیوانی keivany@cc.iut 100319475328460040987 100319475328460040987 No Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. دانشکده منابع طبیعی، دانشگاه صنعتی اصفهان، اصفهان، ایران