University of Isfahan Taxonomy and Biosystematics 3115-9001 14 53 2023 01 21 Phenotype Diversity of Iranian Cichlids Iranocichla spp. in Hormuzgan Basin using the Geometric Morphometrics Technique بررسی تنوع ریختی جمعیت‌های طبیعی سیچلایدماهیان ایرانی Iranocichla spp. در حوضۀ هرمزگان با استفاده از تکنیک ریخت‌سنجی هندسی 1 16 26921 10.22108/tbj.2022.133867.1201 EN Manoochehr Nasri Assistant Professor, Department of Environmental and Fisheries Sciences and Engineering, Faculty of Agriculture and Natural Resources, Lorestan University, Khorramabad, Iran Soheil Eagderi Associate Professor, Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran Elham Jamshidi M.Sc. Graduated, Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran Journal Article 2022 05 29 In the present study, interspecific morphological diversity and sexual dimorphism of Iranocichla spp. were investigated using the geometric morphometrics method in the water bodies of Hormozgan Province, Iran. In this context, 286 specimens of Iranian cichlids were collected from the Mehran, Rasoul, Shoor, and Khoor-e-Goor hot streams and transported to the laboratory. The geometric shapes of the fish were digitized using 17 landmark points, and the data were analyzed after removing non-shape data. According to the results, the fishes of the Mehran River exhibited a deeper caudal peduncle, a higher caudal-fin base, and a longer body, reflecting their adaptation to lentic conditions. Fishes living in pool environments in Khoor-e-Goor had shorter snouts and deeper bodies, indicating adaptive phenotypic plasticity to lotic conditions. Conversely, the fishes of the Rasoul and Shoor rivers displayed traits common to other groups, showing morphological adaptations to lotic conditions during rainfall seasons and to lentic conditions in dry seasons with strong selective pressures. Sexual dimorphism in head traits observed in the Khoor-e-Goor and Rasoul taxa may be related to the mouth-breeding function in females, which requires a larger buccal cavity. Finally, the observed differences between the studied groups can be attributed to ongoing adaptive phenotypic plasticity in response to selective environmental pressures. Introduction Iran, with its 19 basins, boasts a diverse range of biological components from the Palearctic, Ethiopian, and Oriental biogeographical realms. The composition of Iranian inland water fishes is the result of a combination of natural geographical events and human-induced habitat segregation. To date, two species of Cichlids have been reported in Iran, namely Iranocichla hormuzensis and Iranocichla persa. Most populations of Iranian cichlids are distributed in hot springs in Hormuzgan and southern Fars provinces. The varied geographical and climatological conditions in Iran highlight the need for more extensive taxonomical studies on the country's inland water fishes. The Iranian native cichlids, Iranocichla spp., belonging to the Cichlidae family, are taxa of African origin that have become isolated in the region. They possess significant ecological, biodiversity, and aquaculture values. Materials and Methods In this study, intra-population morphological diversity and sexual dimorphism of Iranocichla spp. and their distinctiveness were investigated using landmark-based geometric morphometrics methods in the water bodies of Hormozgan Province, Iran. For this purpose, 286 specimens of Iranian cichlids were collected from the Mehran, Rasoul, Shoor, and Khoor-e-Goor hot streams using electrofishing. All specimens were anesthetized with 1% clove oil extract, fixed in 4% formaldehyde, and then transported to the laboratory for further analysis. The geometric shapes of the fish were digitized using 17 morphological landmark points with the aid of TPSDig2 software. All non-shape data, including size, scale, and direction, were removed using Generalized Procrustes Analysis (GPA). The data were then analyzed using statistical programs PAST and MorphoJ, employing multivariate methods such as MANOVA/CVA, DFA, and Cluster Analysis. Findings The obtained results between the coordinates of morphological landmarks and Procrustes distances (r=1) confirmed the validity of Procrustes distances for statistical analyses. The results of the MANOVA/CVA indicated significant statistical differences between all taxa (Wilk's Lambda = 0.033, F = 18.5, P < 0.001). The greatest morphological differences were observed between the Mehran and Khoor-e-Goor populations, while the least differences were noted between the Rasoul and Shoor populations. Cluster analysis with 1,000 permutations corroborated the MANOVA/CVA results. Accordingly, the Rasoul-Shoor specimens were grouped together with 53% support, but the Mehran specimens were distinctly separated from the others with 100% support. The only observed sexual morphological dimorphism was found in the Rasoul specimens. Conclusions and Results Habitat-related morphological differentiation has been confirmed in many studies. In the present research, the distinct ecological differences between habitats were apparent. Khoor-e-Goor, a hot sulfur spring, exhibits lentic conditions, while Mehran represents a lotic ecosystem. Rasoul and Shoor, being permanent rivers, demonstrate some lentic conditions, especially in dry seasons. The bottleneck effect is one of the outcomes of ecological selective pressures. The Cichlidae family is renowned for its considerable morphological plasticity, particularly in the buccal region, which is linked to feeding and breeding functions. This group of fish is well-known for their rapid and diverse morphological adaptations in response to ecological segregation pressures. Our findings confirmed the adaptability and morphological plasticity of these species in response to ecological conditions. Ultimately, the observed differences between the studied groups can be attributed to ongoing adaptive phenotypic plasticity, influenced by selective environmental pressures.

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