The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform
George F Turner - One of the best experts on this subject based on the ideXlab platform.
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courtship and agonistic sounds by the cichlid fish Pseudotropheus zebra
Journal of the Acoustical Society of America, 2008Co-Authors: Miguel J Simoes, George F Turner, Paulo J Fonseca, Ine S G Duarte, Clara M P AmorimAbstract:Courtship and agonistic interactions in an African cichlid species present a richer diversity of acoustic stimuli than previously reported. Male cichlids, including those from the genus Pseudotropheus (P.), produce low frequency short pulsed sounds during courtship. Sounds emitted by P. zebra males in the early stages of courtship (during quiver) were found to be significantly longer and with a higher number of pulses than sounds produced in later stages. During agonistic intrasexual quiver displays, males produced significantly longer sounds with more pulses than females. Also, male sounds had a shorter duration and pulse period in courtship than in male–male interactions. Taken together, these results show that the acoustic repertoire of this species is larger than what was previously known and emphasize the importance of further research exploiting the role of acoustic stimuli in intra- and interspecific communication in African cichlids.
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african cichlid Pseudotropheus spp males moan to females during foreplay
Journal of Fish Biology, 2008Co-Authors: Jose Miguel Simoes, George F Turner, Paulo J Fonseca, Maria Clara Pessoa AmorimAbstract:This study describes a new courtship sound (moan) produced by Pseudotropheus spp. males, not previously reported for cichlids. Moans are short tonal sounds often showing frequency modulation. This sound type is of very low amplitude and is produced when males swim in close proximity to a female, usually before performing more exuberant behavioural exhibitions, such as darting, quivering the body and growling.
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species differences in courtship acoustic signals among five lake malawi cichlid species Pseudotropheus spp
Journal of Fish Biology, 2008Co-Authors: Maria Clara Pessoa Amorim, Jose Miguel Simoes, Paulo J Fonseca, George F TurnerAbstract:Male courtship acoustic signals from five Lake Malawi cichlid fish species of the Pseudotropheus zebra complex were recorded and compared. Sounds made by males of P. zebra, Pseudotropheus callainos and the undescribed species known as Pseudotropheus ‘zebra gold’ from Nkhata Bay, and Pseudotropheus emmiltos and Pseudotropheus faizilberi from Mphanga Rocks, differed significantly in the number of pulses and in pulse period. The largest differences in acoustic variables were found among the sympatric Mphanga Rocks species that, in contrast to the other three species, show relatively minor differences in male colour and pattern. These findings suggest that interspecific mate recognition is mediated by multimodal signals and that the mass of different sensory channels varies among sympatric species groups. This study also showed that sound peak frequency was significantly negatively correlated with male size and that sound production rate increased significantly with courtship rate.
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female preference for conspecific males based on olfactory cues in a lake malawi cichlid fish
Biology Letters, 2005Co-Authors: Martin Plenderleith, Cock Van Oosterhout, Rosanna L Robinson, George F TurnerAbstract:Research on reproductive isolation in African cichlid fishes has largely focused on the role of nuptial colours, but other sensory modes may play an important role in mate choice. Here, we compare the relative importance of visual and olfactory cues in mate recognition by females of a Lake Malawi cichlid species. Female Pseudotropheus emmiltos were given a choice of spawning next to a conspecific male or a male of the closely-related sympatric Pseudotropheus fainzilberi. Significant preference for conspecific males only occurred when olfactory cues were present. This suggests that divergence of olfactory signals may have been an important influence on the explosive radiation of the East African species flock.
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laboratory mating trials indicate incipient speciation by sexual selection among populations of the cichlid fish Pseudotropheus zebra from lake malawi
Proceedings of The Royal Society B: Biological Sciences, 2004Co-Authors: Mairi E Knight, George F TurnerAbstract:It has been suggested that sexual selection may have played a major role in the rapid evolution of hundreds of species of cichlid fishes in Lake Malawi. We report the results of a laboratory test of assortative mating among Lake Malawi cichlid fishes from five closely related geographical populations differing in male courtship colour. Paternity of clutches was tested using microsatellite DNA typing of offspring. Out of 1955 offspring typed, 1296 (66.3%) were sired by the male from the same population as the female, which is more than three times the rate expected if females do not differentiate among males of the different populations (20%). This result indicates that mate preferences of geographical races are strongly differentiated, consistent with the races representing incipient geographical species diverging under sexual selection exerted by female preferences for different male courtship colours.
Vera Schluessel - One of the best experts on this subject based on the ideXlab platform.
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discrimination of movement and visual transfer abilities in cichlids Pseudotropheus zebra
Behavioral Ecology and Sociobiology, 2018Co-Authors: Vera Schluessel, Jenny Hiller, Monique KruegerAbstract:Fish rival birds and mammals in many of their cognitive skills, and have been shown to successfully discriminate between a range of stationary and moving objects. The present study tested the ability of Pseudotropheus zebra to recognize unique movement patterns shown in the form of a single moving dot, point displays (PDs), point-light displays (PLDs), and videos of moving organisms in two alternative forced-choice experiments. Cichlids successfully distinguished between (1) different directions of movement, (2) a biological vs. a random movement, (3) a biological (human walking) vs. a scrambled motion pattern, and (4) two biological motion patterns (human walking to the left vs. to the right). Following training in (3), it was tested if the walking human was also correctly identified when either the positive, the alternative, or both stimuli were altered or presented inverted; following training in (4), stimuli were presented inverted or moving backwards. With the exception of the presentation of inverted and backwards-moving stimuli, fish excelled at these tasks. Furthermore, cichlids successfully discriminated between videos of different organisms such as eel vs. trout, human vs. dog, eagle vs. bat, and dolphin vs. shark. Following each training, a series of transfer tests elucidated whether P. zebra could also recognize these organisms when shown in transfer test trials (a) from a different perspective (front or sideways), (b) enlarged or downsized, or (c) as PDs. With few exceptions, all individuals learned all tasks and significantly often chose the previously reinforced (but altered) training stimulus over the alternative one during transfer tests. This indicates that cichlids have the ability to recognize a familiar organism under new conditions, for example, based on its movement alone, which may be helpful in recognizing approaching predators early on. Fish can solve a variety of learning and memory tasks including visual discrimination of objects. Here it was tested if cichlids (Pseudotropheus zebra) can distinguish between pairs of videos featuring individually moving dots, dot patterns and moving organisms. Overall, fish were very successful and solved most of the presented tasks. They differentiated between movement directions and movement types, recognized stimuli in transfer tests under altered conditions, and identified familiar organisms when shown resized, from new perspectives or in form of point displays. To be able to recognize movement and to identify organisms based on their specific movement patterns (alone) in the wild is essential to individual survival, as predators, conspecifics and/or prey are usually mobile. Additionally, predators are often encountered at night or when light levels are low, making it harder to successfully distinguish general body features such as coloration and adding significance to being able to quickly recognize motion cues. It should be equally advantageous to be able to recognize organisms such as predators from unfamiliar perspectives. Stimuli used in this study were not of any ecological relevance; they were chosen purely for their characteristic type of movement and just served as vectors to determine transfer abilities of gained knowledge onto new situations. Nonetheless, having excelled at tasks using these stimuli, it seems quite likely that cichlids would perform even better under ecologically significant conditions.
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symmetry perception in bamboo sharks chiloscyllium griseum and malawi cichlids Pseudotropheus sp
Animal Cognition, 2014Co-Authors: Vera Schluessel, O Beil, T Weber, Horst BleckmannAbstract:Several species have been shown to perceive symmetry as a measure of superior genetic quality, useful for assessing potential mates or mediating other visual activities such as the selection of food sources. The current study assessed whether Pseudotropheus sp. and Chiloscyllium griseum, two fish species from distantly related groups, possess symmetry perception. In alternative two choice experiments, individuals were tested for spontaneous preferences and trained to discriminate between abstract symmetrical and asymmetrical stimulus pairs. Pair discriminations were followed by extensive categorization experiments. Transfer tests elucidated whether bilaterally symmetrical and rotationally symmetrical stimuli could be distinguished. Sharks were also tested for the degree of dissimilarity between two symbols that could still be detected. While sharks showed both a spontaneous preference for symmetry as well as remarkable discrimination abilities by succeeding in all of the presented tasks, cichlids showed no spontaneous preference, had difficulties in discriminating between symbols and performed poorly in the categorization experiments. Sharks distinguished between bilaterally and rotationally symmetrical stimuli and easily differentiated between a four-armed cross (all arms 90° apart) and a cross where one of the arms was only 45° spaced from the one next to it. Performance did not decline when the separation was extended to 70°, but was significantly reduced at an 80° separation. Results indicate that the ability for symmetry perception varies across fish species and individuals, whereby some can detect even subtle differences in this respect.
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cognitive abilities in malawi cichlids Pseudotropheus sp matching to sample and image mirror image discriminations
PLOS ONE, 2013Co-Authors: Stefanie Gierszewski, Horst Bleckmann, Vera SchluesselAbstract:The ability to recognize and distinguish between visual stimuli is fundamental for everyday survival of many species. While diverse aspects of cognition, including complex visual discrimination tasks were previously successfully assessed in fish, it remains unknown if fish can learn a matching-to-sample concept using geometrical shapes and discriminate between images and their mirror-image counterparts. For this purpose a total of nine Malawi cichlids (Pseudotropheus sp.) were trained in two matching-to-sample (MTS) and three two-choice discrimination tasks using geometrical, two-dimensional visual stimuli. Two out of the three discrimination experiments focused on the ability to discriminate between images and their mirror-images, the last was a general discrimination test. All fish showed quick associative learning but were unable to perform successfully in a simultaneous MTS procedure within a period of 40 sessions. Three out of eight fish learned to distinguish between an image and its mirror-image when reflected vertically; however none of the fish mastered the task when the stimulus was reflected horizontally. These results suggest a better discrimination ability of vertical compared to horizontal mirror-images, an observation that is widespread in literature on mirror-image discrimination in animals. All fish performed well in the general visual discrimination task, thereby supporting previous results obtained for this species.
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visual discrimination and object categorization in the cichlid Pseudotropheus sp
Animal Cognition, 2012Co-Authors: Vera Schluessel, G Fricke, Horst BleckmannAbstract:Object categorization is an important function of the visual system, quickly providing an animal with relevant information about its surrounding and current situation, as for example during predator detection. While the ability to cate- gorize objects has already been observed in several vertebrate and even invertebrate species, no attempt has previously been made to evaluate this function in fish, the most species-rich vertebrate group. This study assessed form discrimination abilities and object categorization skills in the African cichlid Pseudotropheus sp. Fish could discriminate between a variety of two-dimensional geometrical shapes, forms and sizes and learned to distinguish between two categories, ''fish'' versus ''snail''. Performance remained undisturbed by extensive modifications to the stimuli, as long as key features were maintained. Results indicate that fish not only memorized the features of the positive stimulus (categorized the positive stimulus), but also categorized the negative stimulus. During transfer trials involving a previously unknown object, fish were able to discriminate between both the negative and the positive stimulus and the unknown stimulus and responded accordingly.
Horst Bleckmann - One of the best experts on this subject based on the ideXlab platform.
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symmetry perception in bamboo sharks chiloscyllium griseum and malawi cichlids Pseudotropheus sp
Animal Cognition, 2014Co-Authors: Vera Schluessel, O Beil, T Weber, Horst BleckmannAbstract:Several species have been shown to perceive symmetry as a measure of superior genetic quality, useful for assessing potential mates or mediating other visual activities such as the selection of food sources. The current study assessed whether Pseudotropheus sp. and Chiloscyllium griseum, two fish species from distantly related groups, possess symmetry perception. In alternative two choice experiments, individuals were tested for spontaneous preferences and trained to discriminate between abstract symmetrical and asymmetrical stimulus pairs. Pair discriminations were followed by extensive categorization experiments. Transfer tests elucidated whether bilaterally symmetrical and rotationally symmetrical stimuli could be distinguished. Sharks were also tested for the degree of dissimilarity between two symbols that could still be detected. While sharks showed both a spontaneous preference for symmetry as well as remarkable discrimination abilities by succeeding in all of the presented tasks, cichlids showed no spontaneous preference, had difficulties in discriminating between symbols and performed poorly in the categorization experiments. Sharks distinguished between bilaterally and rotationally symmetrical stimuli and easily differentiated between a four-armed cross (all arms 90° apart) and a cross where one of the arms was only 45° spaced from the one next to it. Performance did not decline when the separation was extended to 70°, but was significantly reduced at an 80° separation. Results indicate that the ability for symmetry perception varies across fish species and individuals, whereby some can detect even subtle differences in this respect.
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cognitive abilities in malawi cichlids Pseudotropheus sp matching to sample and image mirror image discriminations
PLOS ONE, 2013Co-Authors: Stefanie Gierszewski, Horst Bleckmann, Vera SchluesselAbstract:The ability to recognize and distinguish between visual stimuli is fundamental for everyday survival of many species. While diverse aspects of cognition, including complex visual discrimination tasks were previously successfully assessed in fish, it remains unknown if fish can learn a matching-to-sample concept using geometrical shapes and discriminate between images and their mirror-image counterparts. For this purpose a total of nine Malawi cichlids (Pseudotropheus sp.) were trained in two matching-to-sample (MTS) and three two-choice discrimination tasks using geometrical, two-dimensional visual stimuli. Two out of the three discrimination experiments focused on the ability to discriminate between images and their mirror-images, the last was a general discrimination test. All fish showed quick associative learning but were unable to perform successfully in a simultaneous MTS procedure within a period of 40 sessions. Three out of eight fish learned to distinguish between an image and its mirror-image when reflected vertically; however none of the fish mastered the task when the stimulus was reflected horizontally. These results suggest a better discrimination ability of vertical compared to horizontal mirror-images, an observation that is widespread in literature on mirror-image discrimination in animals. All fish performed well in the general visual discrimination task, thereby supporting previous results obtained for this species.
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visual discrimination and object categorization in the cichlid Pseudotropheus sp
Animal Cognition, 2012Co-Authors: Vera Schluessel, G Fricke, Horst BleckmannAbstract:Object categorization is an important function of the visual system, quickly providing an animal with relevant information about its surrounding and current situation, as for example during predator detection. While the ability to cate- gorize objects has already been observed in several vertebrate and even invertebrate species, no attempt has previously been made to evaluate this function in fish, the most species-rich vertebrate group. This study assessed form discrimination abilities and object categorization skills in the African cichlid Pseudotropheus sp. Fish could discriminate between a variety of two-dimensional geometrical shapes, forms and sizes and learned to distinguish between two categories, ''fish'' versus ''snail''. Performance remained undisturbed by extensive modifications to the stimuli, as long as key features were maintained. Results indicate that fish not only memorized the features of the positive stimulus (categorized the positive stimulus), but also categorized the negative stimulus. During transfer trials involving a previously unknown object, fish were able to discriminate between both the negative and the positive stimulus and the unknown stimulus and responded accordingly.
Derya Guroy - One of the best experts on this subject based on the ideXlab platform.
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ciklit baliklarinda albinolugun ureme performansi uzerine etkisi mavi ve beyaz prenses Pseudotropheus socolofi ornegi
Ege Journal of Fisheries and Aquatic Sciences, 2015Co-Authors: Onur Karadal, Derya GuroyAbstract:Albinoluk, melanin pigmentinin az uretilmesinden veya hic uretilmemesinden kaynaklanan ve tum omurgali ve omurgasiz canli gruplarinda gorulebilen genetik bir bozukluktur. Dogal ortamlarda bircok balik turunde albinoluk gorulmektedir. Bu turlere akvaryum sektorunde en cok ele alinan balik gruplarindan olan ciklitler de dahildir. Ozellikle mavi prenses ( Pseudotropheus socolofi ) turu akvaristler tarafindan sikca tercih edilen ve albinosu da beyaz prenses ( Pseudotropheus socolofi var. albino ) olarak adlandirilan bir varyetedir. Bu calismada, mavi prenses ciklitler ile bu turun albinosu olan beyaz prenses ciklitlerin ureme performanslari karsilastirilmistir. Calisma, kapali devre bir sistemde bulunan 6 adet 450 L’lik fiberglas tankta 3 tekrarli olarak yurutulmustur. Her bir tanka 11,76±0,12 g agirliginda ve 8,1±0,3 cm total boya sahip ve 1:4 (erkek:disi) cinsiyet oraninda 25 adet (5 erkek, 20 disi) birey konulmustur. Ureme performansinin belirlenmesi icin kusturma yontemiyle disi baliklarin agzindan yumurta alinmis ve sayilmistir. 12 hafta sonunda, toplamda 570±25 yumurta-yavru ile mavi prenses ciklitler daha verimli ve beyaz prenses ciklitler ise toplamda 270±12 yumurta-yavru ile oldukca dusuk bir ureme performansi gostermislerdir (P<0,05). Sonuc olarak P. socolofi turunde, albino bireylerin normal bireylere gore cok daha dusuk bir ureme performansi sergiledikleri ortaya konulmustur.
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effect of dietary protein level on growth performance and nitrogen excretion of the yellow tail cichlid Pseudotropheus acei
Israeli Journal of Aquaculture-bamidgeh, 2012Co-Authors: Derya Guroy, Betül Güroy, Aytac Altin, Daniel L Merrifield, Canakkale OnsekizAbstract:A 12-week growth trial was conducted to determine the effects of dietary protein on the growth of the yellow tail cichlid, Pseudotropheus acei, and on water quality in closed recirculating systems. Six test diets were formulated to contain protein levels ranging 25-50% by substituting corn oil and α-starch for fishmeal. Diets were assigned to triplicate groups of 10 fish in a completely randomized design. The feed conversion ratios of fish fed the 35% and 50% crude protein diets were significantly (p<0.05) lower than that of fish fed the 30% protein diet. The protein efficiency ratio declined as the dietary protein level increased. Dietary protein levels significantly influenced total ammonia-nitrogen excretion (TAN); fish fed 50% protein excreted higher concentrations of ammonia-nitrogen than fish fed 25-35% dietary protein (p<0.05). Results suggest that inclusion of more than 35% protein in diets containing 10% crude lipid does not benefit juvenile yellow tail growth performance. Further, as TAN excretion and feed costs increased at protein levels beyond 35%, we recommend a diet containing 35% protein and 10% lipid for promoting good growth of juvenile yellow tail cichlids under the conditions used in the present trial. The IJA appears exclusively as a peer-reviewed on-line open-access journal at http://www.siamb.org.il. Only registered persons are able to access full papers. To register free of charge, complete and return our registration form.
Nalan Ozgur Yigit - One of the best experts on this subject based on the ideXlab platform.
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Reversible sterilization by supplementing turmeric (Curcuma longa) powder to diets of female Pseudotropheus socolofi
Fish Physiology and Biochemistry, 2020Co-Authors: Seval Bahadir Koca, Nalan Ozgur Yigit, Hasan Batuhan Emre Ozdogan, Ozlem OzmenAbstract:This study was conducted to determine if diets supplemented with turmeric powder ( Curcuma longa ) affected the reversible sterilization of Pseudotropheus socolofi . Three experimental diets were formulated to contain 0%, 10%, and 14% turmeric powder. The fish (mean weight 13 g) were randomly divided into groups consisting of 1 male and 4 females for each aquarium and were kept together for 137 days. The control group was fed a diet without turmeric, while the others were fed diets with turmeric for the first 75 days. All groups were then fed the control diet from day 75 to 137. The results showed that turmeric powder supplementation did not affect growth performance ( p ˃ 0.05). A histopathological examination of the ovaries, performed on two samples on days 75 and 137, revealed that high doses of turmeric decreased number of ovulated vitellogenic follicles and ovarian activity. Moreover, immature follicle density was excessive in groups fed turmeric powder. However, the number of ovulated vitellogenic follicles increased in groups fed diets containing 10% and 14% turmeric after feeding them with the turmeric-free control diet from day 75 to 137. In conclusion, the study revealed that supplementing diets with high ratios of turmeric can influence ovarian activity; however, these effects can be reversed by ceasing supplementation.
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The effects of Isatis tinctoria extract on diseases resistance against Aeromonas hydrophila and pigmentation, growth of Pseudotropheus acei
Turkish Journal of Agriculture: Food Science and Technology, 2019Co-Authors: Muhammed Bıyıklı, Seval Bahadir Koca, Nalan Ozgur Yigit, Seçil Metin, Nimet Kara, Gökhan GürbüzerAbstract:This study was conducted with aim to investigate the effects of Isatis tinctoria leaves extract on growth performance, pigmentation and protection against Aeromonas hydrophila of Pseudotropheus acei. Five diets were prepared by adding four different ratios fish woad extraction (Woad: W1: 1%, W1.5: 1.5 %, W2: 2 %, W2.5: 2.5% and C: control diet 0 %). Three replicates were conducted for each treatment. One hundred twenty fish and 15 tanks (80 x 30 x 80 cm) were used in recirculating system. In the end of 90 days, there were no differences in terms of weight gain, FCR and SGR of Pseudotropheus acei feed with diets added with different levels of Isatis tinctoria extraction compare to control group. Isatis tinctoria extract was not found effect on survival rates in Pseudotropheus acei after A. hydrophila infection. However, there were no differences on pigmentation of Pseudotropheus acei. Isatis tinctoria extract administration did not provide protection against Aeromonas hydrophila infection.
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the effects of dietary administration with red pepper capsicum annuum on growth performance coloration histology and protection against aeromonas sobria in yellow tail cichlid Pseudotropheus acei
Acta Aquatica Turcica, 2019Co-Authors: Nalan Ozgur Yigit, Seval Bahadir Koca, Ozlem Ozmen, Behire Isil Didinen, Seçil MetinAbstract:Bu calisma, Pseudotropheus acei' baliklarinda yemlere yuksek seviyede kirmizi biber ilavesinin buyume performansi, renklenme, histoloji, intestinal mikroflora ve Aeromonas sobria 'ya karsi hastalik direnci uzerine etkilerini belirlemek icin yurutulmustur. Kontrol yemine % 15 oraninda biber unu eklenerek Iki izonitrojenik (% 37 ham protein) ve izokalorik (3831kcall / kg enerji) deneme yemleri hazirlanmistir. Besleme denemesi, akvaryumlarda (100 L) uc tekerrur olacak sekilde 90 gun beslenerek yurutulmustur. Denemenin basinda, her akvaryuma yirmi balik (baslangic agirligi 0.06 g) stoklanmistir. Deneme sonunda,yemlere kirmizi biber ilavesi ile beslenen baliklarin agirlik kazanci, yem donusum orani, spesifik buyume orani ve yasama orani uzerine onemli bir etkisi olmamistir. Ancak, kirmizi biber iceren yemlerle beslenen disi baliklarin kuyrugunda pigmentasyonun onemli derecede arttigi gorulmustur. Yemlere yuksek seviyede kirmizi biber eklenmesi hicbir organda patolojik bir bulguya neden olmamistir. Kirmizi biber, A. sobria enfeksiyonuna karsi korumada onemli bir farklilik gostermemistir. Kirmizi biber grubunda Aeromas ve Pseudomonas sayilari kontrol gruplarina gore anlamli derecede dusukt bulunmustur.
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subfertility effects of turmeric curcuma longa on reproductive performance of Pseudotropheus acei
Animal Reproduction Science, 2019Co-Authors: Seval Bahadir Koca, Ozlem Ozmen, Omer Ongun, Nalan Ozgur YigitAbstract:This study was conducted to determine the effect of turmeric powder dietary supplementation on the histology of visceral organs and reproductive performance of Pseudotropheus acei. The fish were fed dietary additions of 0%, 1%, 3%, 5%, and 7% turmeric powder. Each treatment was replicated three times. There were one male and four female fish with a mean weight of 6 g in each replicate. The fish were fed ad libitum for 90 days. There were no differences in fertility rate, fecundity rate, hatching rate, egg diameter, and larvae survival rate among groups (P < 0.05). Ovulation frequency and the percent of spawning broodstock were less in the 7% and 5% turmeric-supplemented group (P < 0.05), while there were no effects of treatment in the 1%, and 3% groups compared with the control group. Observations in histopathological examinations indicated there were normal tissue structures in the control, 1% and 3% turmeric-supplemented groups, while the addition of 5% and 7% turmeric induced a degeneration of and decrease in number of observable ovarian follicles. In addition, there was a normal liver structure in the control and the 1% and 3% turmeric-supplemented groups and slight to severe lipidosis in the 5% and 7% turmeric-supplemented groups. Also, the supplementation of larger amounts of turmeric induced enteritis and the slight to severe side effects on the relevant organs. These results indicate that supplementing of diets with turmeric powder in amounts of 5% and 7% suppressed ovarian follicle development, and extended periods between times of spawning which resulted in subfertility of broodstocks.
