بررسی تنوع ریختی جمعیت‌های طبیعی سیچلایدماهیان ایرانی iranocichla spp. در حوضۀ هرمزگان با استفاده از تکنیک ریخت‌سنجی هندسی

در این مطالعه تنوع ریختی بین آرایه‌‌ای و بین جنسیتی سیچلایدماهیان ایرانیiranocichla spp. و امکان تمایز آنها در منابع آبی استان هرمزگان براساس تکنیک ریخت‌سنجی هندسی مطالعه شد. تعداد 286 قطعه ماهی سیچلایدماهی ایرانی از چهار منبع آبی مجزا شامل رودخانه‌های مهران، رسول و شور و منطقۀ خورگور صید و برای مطالعه به آزمایشگاه منتقل شد. شکل هندسی ماهیان با استفاده از تعداد 17 لندمارک تعریف و رقومی‌سازی و پس از حذف داده‌های غیرشکلی و تایید تناسب مختصات لندمارک‌ها، تجزیه‌وتحلیل شد. براساس نتایج، ماهیان ساکن محیط‌های جاری مانند رود مهران، ساقۀ دمی مرتفع‌تر و قاعدۀ بالۀ دمی وسیع‌تر و همچنین بدنی کشیده‌تر داشتند که برای سازگاری با شرایط آب‌های جاری کارآمد است. ماهیان ساکن محیط‌های حوضچه‌ای مانند خورگور نیز دارای پوزه‌ای کوتاه و بدنی مرتفع‌تر بودند که نوعی سازگاری برای شرایط آب‌های ساکن محسوب می‌شود؛ همچنین ماهیان رودخانه‌های شور و رسول ازنظر ریختی صفاتی مشترک با هر دو گروه قبلی داشتند که انعکاسی از شرایط توام محیط جاری در فصول بارانی و محیط حوضچه‌ای در فصول خشک به همراه فشارهای گزینشگر سخت‌گیرانۀ محیطی است. مشاهدۀ تفاوت ریختی بین جنس‌های نر و ماده در خورگور و رود رسول در ناحیۀ سر ممکن است با نیاز ماهیان ماده برای محفظۀ دهانی بزرگ‌تر به‌منظور مراقبت از نوزادان مرتبط باشد. درنهایت، امکان در نظر گرفتن مشاهدۀ تفاوت‌های ریختی در ماهیان مطالعه‌‌شده، در نقش الگوی تکامل پیش‌رونده براساس شکل هندسی سیچلایدماهیان ایرانی در پاسخ به شرایط گزینشگر محیطی وجود دارد.

phenotype diversity of iranian cichlids iranocichla spp. in hormuzgan basin using the geometric morphometrics technique

in the present study, interspecific morphological diversity and sexual dimorphism of iranocichla spp. and their distinctness were investigated using the geometric morphometrics method in the water bodies of the hormozgan province, iran. in this regard, 286 specimens of iranian cichlids were collected from the mehran, rasoul, shoor, and khoor-e-goor hot stream 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 mehran river showed deeper caudal peduncle, higher caudal-fine base, and longer body expressing their adaptation to lentic conditions. fishes living in pool environments in khoor-e-goor have a shorter snout and deeper body showing adaptive phenotypic plasticity to lotic conditions. on the other hand, the fishes of rasoul and shoor rivers revealed common traits with other groups showing some morphological adaptations to lotic conditions during rainfall seasons and lentic conditions in dray seasons with rigid selective pressures. sexual dimorphism of khoor-e-goor and rasoul taxa in head traits may be related to mouth-breeding function in females that need a bigger buccal cavity. finally, the observed differences between the studied groups can be related to ongoing adaptive phenotypic plasticity to the selective environmental pressures.key words: natural selection, biodiversity, biogeography, fish conservation, iranian native fishes. introductioniran has 19 basins and diverse biological components from palearctic, ethiopian, and oriental biogeographical realms. iranian inland water fishes are the results of a mixture of natural geographical events and human-caused habitat segregation. two species of cichlids were reported from iran including iranocichla hormuzensis and iranocichla persa. most populations of iranian cichlids are dispersed in hot springs in hormuzgan and southern fars provinces. the diverse geographical and climatological conditions in iran emphasize more taxonomical studies on inland water fishes of the country. iranian native cichlids iranocichla spp. from the cichlidae family as a taxon of african origin that is isolated in the region have high ecological, biodiversity, and aquaculture values. materials and methodsin this study, intrapopulation morphological diversity and sexual dimorphism of iranocichla spp. and their distinctness were investigated using landmark-based geometric morphometrics methods in the water bodies of the hormozgan province, iran. for this purpose, 286 specimens of iranian cichlids were collected using electrofishing from the mehran, rasoul, shoor, and khoor-e-goor hot stream. all specimens were anesthetized in 1% clove oil extract, fixed in 4% formaldehyde, and transported to the laboratory for further analyses. the geometric shapes of the fish were digitized using 17 morphological landmark points using tpsdig2. all non-shape data including size, scale, and direction were removed using generalized procrustes analyses (gpa) and the data were analyzed using statistical programs past and morphoj based on multivariate methods manova/cva, dfa, and cluster analysis. findingsthe obtained regression results between coordinates of morphological landmarks and procrustes distances (r=1) confirmed the obtained procrustes distances for statistical analyses. the results of manova/cva showed significant statistical differences between all taxa (wilk’s lambda=0.033, f=18.5, p<0.001). the most and the least morphological differences were observed between mehran, khoor-e-goor, and rasoul-shoor, respectively. cluster analyses with 1000 permutations confirmed the manova/cva results. accordingly, rasoul-shoor specimens were clustered in a single group with 53% support but mehran specimens were separated from the others with 100% support. the only observed sexual morphological dimorphism was between rasoul specimens. conclusions and resultshabitat-related morphological differentiation is confirmed in many studies. in the present study, various ecological differences between habitats were obvious. khoor-e-goor is a hot sulfur spring with lentic conditions, but mehran is a lotic ecosystem. rasoul and shoor are permanent rivers, some lentic conditions can be seen especially in dry seasons. the bottleneck effect is one of the consequences of ecological selective pressures. cichlidae is one of the most famous fish families due to their huge morphological plasticity abilities, especially in the buccal region related to feeding and breeding functions. this group of fish is well known for their fast and various morphological responses to ecological separation pressures. our findings confirmed the adaptability and morphological plasticity responding to ecological conditions. finally, the observed differences between studied groups can be related to ongoing adaptive phenotypic plasticity to the selective environmental pressures.