Poecilia Reticulata Research Articles

Effects of Tribulus terrestris and Basella alba Extract on Sex Reversal on Poecilia reticulata

This study examined the effects of Tribulus terrestris and Basella alba on sex reversal in the guppy, Poecilia reticulata. This study aimed to introduce a new environmentally friendly method for masculinization in P. reticulata. Since male guppy has higher commercial value than females. T. Terrestris (ET) and Basella alba (EB) are a natural, non-toxic herb that helps enhance testosterone levels in humans and animals. Different concentrations (0.0, 5.0, 10.0, and 15.0 g L-1) of ET and EB were investigated for sex reversal in P. reticulata. The plant extracts were administered by immersion of newly hatched offspring once a week for two months. The dosage of 15.0, g L-1 ET was the most effective dosage that ensured a maximum male ratio (82.0, p<0.01). Although, sex ratios of fish in treatment 5.0 and 10.0 g L-1 ET were not significantly different from the expected 1:1 ratio, in these two groups treatment with ET and EB also resulted in a higher number of males (71.9 and 61.1; 82.0 and 78.5, respectively), than control (p>0.05). Total survival rates in all treatments and control were uniformly high ranging from 92% and 97% (p>0.05). It is concluded that ET has no negative effect on the survival rate of P. reticulata. All groups of ET-treated fish exhibited growth acceleration compared to the control group, but only ET treatment at the concentration of 15 and 10 g L-1 ET significantly improved growth rate of P. reticulata (p<0.01). Histological examinations revealed that the testes of fish treated with ET and EB extract contained all stages of spermatogenesis. Sex reversal in P. reticulata demonstrated that ET and EB-treated progenies showed successful sex reversal, spermatogenesis, and better growth rate than untreated progenies.

Adulticidal synergy of two plant essential oils and their major constituents against the housefly Musca domestica and bioassay on non-target species

Single and mixture formulations of lemongrass (Cymbopogon citratus (DC.) Stapf.) and star anise (Illicium verum (J. Presl.)) essential oils (EOs) and their major constituents were assayed for their adulticidal activities against housefly, Musca domestica L., and two non-target species, stingless bee (Tetragonula pegdeni Schwarz) and guppy (Poecilia reticulata Peters). The efficacies of the mixture formulations were compared against those of the single formulations and 1.0% α-cypermethrin, a common synthetic insecticide. GC-MS analysis found that the major constituent of lemongrass EO was geranial (45.23%), and that of star anise EO was trans-anethole (93.23%). Almost all mixture formulations were more effective in adulticidal activity against housefly adults than single formulations and 1.0% α-cypermethrin. A mixture of 1.0% lemongrass EO + 1.0% trans-anethole exhibited the strongest synergistic insecticidal activity with a 100% mortality rate (KT50 of 3.2 min and LT50 of 0.07 h). The relative percentage increase in mortality rate over single formulations was between 1.6 and 91.9%. In addition, it was three times more effective than 1.0% α-cypermethrin. To find the mechanism of adulticidal action, scanning electron microscopy (SEM) was done to find morphological aberrations, such as antennal and mouthpart aberrations, after the houseflies were treated with 1.0% lemongrass EO + 1.0% trans-anethole. The aberrations included deformed and abnormal shape of arista and flagellum, change in labellum pigmentation, and damage to pseudotracheae. Regarding toxicity against non-target species, all single and mixture formulations were not toxic to the two non-target species, while 1.0% α-cypermethrin was highly toxic. To conclude, a mixture of 1.0% lemongrass EO + 1.0% trans-anethole can be an excellent, natural, sustainable housefly adulticidal agent.

Toxicological properties of plant-based disinfectants

The article presents the results of research on the toxicity determination of phytopreparations in the composition of common powdery mildew + calamus + pear Late November + bischofite; common powdery mildew + calamus + bischofite; pear Late November + bischofite, which have a universally broad spectrum of bactericidal action against Staphylococcus aureus and Escherichia coli. When studying the toxicity of phytopreparations on guppy fish, it was found that when adding the infusion to water in the composition of common powdery mildew + calamus + pear Late November + bischofite with exposures of 30 minutes and 60 minutes, all fish in a group of 10 had an adverse reaction. With an exposure of 24 hours, mortality reached up to 20 %. The highest fish mortality occurred at 24 hours in the composition of common powdery mildew + calamus + bischofite, with a mortality rate of 40 %. The composition of pear in late November + bischofite showed no signs of toxicity; all fish in the group remained alive during the study. Visually, motor activity, behavioral reactions, changes in skin pigmentation, and breathing intensity were average. The survey of skin-irritating effects of phytopreparations was conducted on laboratory animals in 20 individuals – Alaska breed rabbits. It was established that during the observation period, the following signs were absent: the presence of temperature; moderately expressed, expressed, and sharply expressed erythema; pain (with a slight thickening of the skin followed by flaking); pain, swelling, and ulcers (thickening of the skin in the application area on the rabbit). After applying phytopreparations to the skin of rabbits with exposures of 1 hour, 24 hours, 48 hours, and 72 hours, no behavioral and visual changes of an inflammatory nature were detected. When applied to the animal's skin, the investigated plant-based disinfectants do not cause irritating, necrotic, or absorptive effects. Throughout the observation period, no visible changes were observed in laboratory animals' experimental and control groups. The conducted research indicates the possibility of safe application of these plant-based disinfectants in the presence of animals.

Sustainable use of plastic-derived nanocarbons as a promising larvicidal and growth inhibitor agent towards control of mosquitoes

Nanoscale carbon was obtained from six widely used plastics (PET, HDPE, PVC, LDPE, PP and PP) via thermal degradation (600 °C) under inert atmosphere. The thermally degraded products were processed through bath sonication followed by lyophilisation and the same was characterized through proximate analysis, UV–Vis spectroscopy, Scanning electron micrograph (SEM) with energy dispersive X-ray (EDX) analysis, Transmission electron micrograph (TEM), Dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). A series of aqueous solution of nanoscale carbon (5–30 mg/L) were prepared and same were used as both mosquito growth inhibitor and larvicidal agent against 3rd and 4th instar larvae of Culex pipiens. The significant percent mortality results were recorded for LDPE (p < 0.007) with average particle size of 3.01 nm and 62.95 W% of carbon and PS (p < 0.002) with average particle size of 12.80 nm and 58.73 W% of carbon against 3rd instar larvae, respectively. Similarly, for 4th instar larvae, both significant pupicidal and adulticidal activity were also recorded for PET (F = 24.0, p < 0.0001 and F = 5.73, p < 0.006), and HDPE (F = 26.0, p < 0.0001) and F = 5.30, p < 0.008). However, significant pupicidal activity were observed for PVC (F = 6.90, p < 0.003), and PS (F = 21.30, p < 0.0001). Histological, bio-chemical and microscopic studies were revealed that nanoscale carbon causes mild to severe damage of external and internal cellular integrity of larvae. However, nanoscale carbon does not exhibit any chromosomal abnormality and anatomical irregularities in Allium cepa and Cicer arietinum, respectively. Similarly, non-significant results with respect to blood cell deformation were also recorded from blood smear of Poecilia reticulata. Therefore, it can be concluded that plastic origin nanoscale carbon could be a viable sustainable nano-weapon towards control of insects.

Garlic Extract as a Bath Treatment against Gyroductylus sp. in Guppy Fish (Poecilia reticulata)

Parasitic infection is considered one of the major constraints in commercial fish farms owing to huge economic losses. Although there are plenty of commercial drugs available for treatments, those synthetic chemicals are more hazardous to the host and the environment than the parasite. Therefore, a special trend can be seen towards herbal medications. The present study is utmost significance as it focused on a well-known spice, Garlic (Allium sativum) as a bath treatment against gyrodactylosis caused by Gyrodactylus sp. The soxhlet extraction method was used to haul out the water-soluble compounds and the major components were identified using Thin-Layer Chromatography (TLC) techniques. During the phytochemical analysis, flavonoids, glycosides, quinones, and diterpenes were identified where the alkaloids, tannins, and phenols were absent in garlic extract. To find out the LC50, values acute toxicity test was performed in 72 hours with triplicates and 802.2ppm value was resulted. 216 of infected adult guppies (2.9 ± 0.1cm, 0.32 ± 0.05 g) were used for a three-hour in vitro bath treatment with different concentrations of garlic extract including 50, 100, 150, 200, and 250 mg/L. Complete recovery from gyrodactylosis is observed by the means of microscopic observations at 3, 2.5, 2, and 1.5 h with 50, 100, 150, and 200mg/L of concentrations, respectively. According to the observations, it can be concluded that exposure to garlic extract caused the parasite to first detach from the host, then restrict its movements, and finally die. A significant negative correlation (p&lt;0.01) can be observed between the garlic concentration and the eradication time. 250 ppm garlic extract bath for 0.5 hours was identified as the optimal and most effective treatment against gyrodactylosis. Therefore, garlic extract can be suggested as a herbal bath treatment against agent Gyrodactylosis infection in guppy fish. &#x0D; Keywords: Bath treatment, LC50, Gyrodactylus sp, Poecilia reticulata

Identification of Philaster apodigitiformis in aquaculture and functional characterization of its β-PKA gene and expression analysis of infected Poecilia reticulata.

Cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) is a distinctive member of the serine–threonine protein AGC kinase family and an effective kinase for cAMP signal transduction. In recent years, scuticociliate has caused a lot of losses in domestic fishery farming, therefore, we have carried out morphological and molecular biological studies. In this study, diseased guppies (Poecilia reticulata) were collected from an ornamental fish market, and scuticociliate Philaster apodigitiformis Miao et al., 2009 was isolated. In our prior transcriptome sequencing research, we discovered significant expression of the β-PKA gene in P. apodigitiformis during its infection process, leading us to speculate its involvement in pathogenesis. A complete sequence of the β-PKA gene was cloned, and quantified by quantitative reverse transcription-polymerase chain reaction to analyse or to evaluate the functional characteristics of the β-PKA gene. Morphological identification and phylogenetic analysis based on small subunit rRNA sequence, infection experiments and haematoxylin–eosin staining method were also carried out, in order to study the pathological characteristics and infection mechanism of scuticociliate. The present results showed that: (1) our results revealed that β-PKA is a crucial gene involved in P. apodigitiformis infection in guppies, and the findings provide valuable insights for future studies on scuticociliatosis; (2) we characterized a complete gene, β-PKA, that is generally expressed in parasitic organisms during infection stage and (3) the present study indicates that PKA plays a critical role in scuticociliate when infection occurs by controlling essential steps such as cell growth, development and regulating the activity of the sensory body structures and the irritability system.

Trophic niche drives the evolution of craniofacial shape in Trinidadian guppies.

Diverse clades of fishes adapted to feeding on the benthos repeatedly converge on steep craniofacial profiles and shorter, wider heads. But in an incipient radiation, to what extent is this morphological evolution measurable and can we distinguish the relative genetic vs. plastic effects? We use the Trinidadian guppy (Poecilia reticulata) to test the repeatability of adaptation and the alignment of genetic and environmental effects shaping poecilid craniofacial morphology. We compare wild-caught and common garden lab-reared fish to quantify the genetic and plastic components of craniofacial morphology across 4 populations from 2 river drainage systems (n = 56 total). We first use micro-computed tomography to capture 3D morphology, then place both landmarks and semilandmarks to perform size-corrected 3D morphometrics and quantify shape space. We find a measurable, significant, and repeatable divergence in craniofacial shape between high-predation invertivore and low-predation detritivore populations. As predicted from previous examples of piscine adaptive trophic divergence, we find increases in head slope and craniofacial compression among the benthic detritivore foragers. Furthermore, the effects of environmental plasticity among benthic detritivores produce exaggerated craniofacial morphological change along a parallel axis to genetic morphological adaptation from invertivore ancestors. Overall, many of the major patterns of benthic-limnetic craniofacial evolution appear convergent among disparate groups of teleost fishes.

Membrane molecule bouncer regulates sperm binding activity in immature oocytes in the viviparous teleost species Poecilia reticulata (guppy).

Generally, in vertebrates, the first step toward fertilization is the ovulation of mature oocytes, followed by their binding to sperm cells outside of the ovary. Exceptionally, the oocytes of poeciliid fish are fertilized by sperm cells within the follicle, and the developmental embryo is subsequently released into the ovarian lumen before delivery. In the present study, we aimed to identify the factor(s) responsible for intrafollicular fertilization in a viviparous teleost species, Poecilia reticulata (guppy). Sperm tracking analysis in this regard indicated that in this species, sperm cells reached immature oocytes including the germinal vesicle, and the insemination assay indicated that the immature oocytes robustly adhered to the sperm cells; similar binding was not observed in Danio rerio (zebrafish) and Oryzias latipes (medaka). We also identified the Ly6/uPAR protein bouncer as the factor responsible for the observed sperm binding activity of the immature oocytes in this species. The recombinant bouncer peptide acted as an inhibitory decoy for the sperm-oocyte binding in guppy. On the other hand, ectopic expression of guppy bouncer in zebrafish oocytes resulted in interspecific sperm-oocyte binding. These results argue that bouncer is responsible for sperm-immature oocyte binding. Our findings highlight the unique reproductive strategies of guppy fish and enhance our understanding of the diverse reproductive mechanisms in vertebrates.

Investigation of extragonadal teratomas in two Poecilia wingei.

Teratoma is a rare tumour in fish consisting of tissues from more than one germ layer, that may be located in either the gonads or extragonadal sites. Teratomas in many fish species remain poorly understood. In this work, we performed the first histological examinations of extragonadal teratomas in Poecilia wingei and also examined the influence of a large teratoma on male sexual activity. The studied teratomas shared general organizational features, but they also had variations in both external and internal features. In teratomas, the most common and highly differentiated tissues were striated muscle and nervous tissue. Despite the tumour, the male P. wingei exhibited normal mating behaviour and retained the ability for successful copulation. The structural features of extragonadal teratomas in guppy fish indicate a possible connection between these tumours and a failure of conserved processes operating in the embryonic germline.

Effects of short‐ and long‐term enrichment on brain and behavior in Trinidadian guppies

AbstractEnvironmental enrichment (EE) often increases positive behavioral and physiological effects on captive animals. Fish are commercially and scientifically important taxa that have been shown to benefit from EE. Here we examined the effects of both short‐ and long‐term EE in Trinidadian guppies (Poecilia reticulata). In the short‐term exposure to EE, female guppies were raised in standard conditions, and after reaching adulthood were moved to either an enriched or a deprived environment for 2 weeks. Long‐term exposure guppies were reared from birth for 12 weeks (until sexual maturity) in either an enriched or deprived environment. We then assessed growth, brain size, and neophobic and exploratory behaviors in standard assays. Guppies given EE were bolder, regardless of timescale, although females showed a more pronounced change in behaviors than males. We further found that guppies reared with EE were smaller yet had larger relative brain sizes than guppies reared under deprived conditions. Here we highlight that EE had influenced growth, brain size, neophobic, and exploratory behaviors in guppies, and behavioral changes were observed after only 2 weeks. Our results highlight the need for assessing the influences of EE in captivity, in particular for researchers studying cognition and behavior.

Infection of guppies (Poecilia reticulata) with the Asian fish tapeworm Schyzocotyle acheilognathi in an urban stream in Brazil.

Schyzocotyle acheilognathi is a fish tapeworm native to Asia but has been reported as an alien species on practically all other continents. Its invasive potential is due to its low host specificity and high adaptability to different environments, and its spread to new areas can result in economic and ecological impacts. Studies reporting this species in South America are still scarce, indicating the need to monitor its dispersion to new areas. Herein, tapeworms found in guppies, Poecilia reticulata, from an urban stream located in Belo Horizonte, Minas Gerais, Brazil, in April 2021 were subjected to morphological and molecular characterization. As a result, 5/13 (38.5%) of the P. reticulata specimens evaluated were infected with intestinal tapeworms. It was verified a mean intensity of infection of 7.8 (1-25) and a mean abundance of infection of 3 (0-25). The morphology of the cestodes obtained was compatible with that of S. acheilognathi. Moreover, genetic analysis based on cytochrome c oxidase subunit 1 gene (Cox-1) revealed 97.89-99.77% similarity to isolates of this species from different localities. The possibility that S. acheilognathi is expanding to new regions of South America is discussed.

Characterization of Piscinoodinium sp. associated with epizootics and mortality in non-native and endemic freshwater fish of the Andaman Islands, India.

Piscinoodinium is a well-known parasitic dinoflagellate genus that causes epizootics in tropical freshwater fish. This study investigated the first outbreak of Piscinoodinium sp. in freshwater fish of the Andaman Islands, India. The infection was noticed in the non-native fish Betta splendens and Poecilia reticulata, and in the endemic killifish Aplocheilus andamanicus. The infection caused mass mortality in larval, sub-adult, and adult fish. The parasite was identified based on microscopy and molecular characterization. The prevalence, parasite density, and mortality percentage were recorded. Infected fish had numerous trophonts attached on the body surface, gills, fins, and eyes. Infected skin and gills showed degeneration of the epithelial cells and clubbed gills. Small subunit rDNA (955 bp) was amplified from the Piscinoodinium sp. infecting B. splendens, revealing genetic differences between it and Piscinoodinium spp. from the USA and from India.

Estrogen regulates the transcription of guppy isotocin receptors.

Estrogen can regulate oxytocin receptor expression, which is mediated through estrogen receptors (ESRs) in mammals, initiating parturition. To further study the reproductive physiological process of ovoviviparous teleosts, guppies (Poecilia reticulata) were employed as the research model in the present study to identify the transcriptional regulation of ESRs on isotocin receptors (itrs). Since guppy embryos develop inside the ovary, in the present study, the levels of itrs in the ovarian stroma of pregnant female guppies treated with estradiol (E2) in vitro were tested. E2 increased only itr2 mRNA levels 3 h post-treatment, with no variation in itr1 mRNA expression levels. In vivo, pregnant guppies were immersed in different concentrations of E2, significantly increasing the relative expression levels of itr1 and itr2 in the ovary. Moreover, based on dual-fluorescence in situ hybridization (ISH), both esrs and itrs mRNAs were localized in the same cells around the embryos in the ovary. To further investigate the regulation of itr transcription by estrogen, a luciferase reporter assay was performed, and the results demonstrated that E2 treatment could induce E2-dependent repression of luciferase activity in cells transfected with ESR1. However, overexpression of ESR2a or ESR2b caused a robust ligand-independent increase in itr2 promoter activity. Deletion analysis of the itr2 promoter indicated that there were novel potential ESR transcription factor-binding sites at -360 bp upstream of the 5' end of the itr2 promoter. Overall, our study provided novel results regarding the ESRs mediating the onset of parturition in ovoviviparous teleosts.

Mosquitocidal Susceptibility and Non-Target Effects of Tricholoma equestre Mushroom (Agaricomycetes) on the Immature Stages of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus.

The worldwide scientific community is well aware that mosquitoes are the sole agents responsible for transmitting various dreadful diseases and critical illnesses caused by vector-borne pathogens. The primary objective of this current research was to evaluate the effectiveness of methanol extract from Tricholoma equestre mushroom in controlling the early life stages of Culex quinquefasciatus Say, Anopheles stephensi Liston, and Aedes aegypti (Linnaeus in Hasselquist) mosquitoes. The larvae, pupae and eggs of these mosquitoes were exposed to four different concentrations (62.5 to 500 ppm). After 120 h of treatment, the methanol extract of T. equestre exhibited ovicidal activity ranging from 66% to 80% against the eggs of the treated mosquitoes. It also demonstrated promising larvicidal and pupicidal activity with LC50 values of 216-300 and 230-309 ppm against the early life stages of all three mosquito species. Extensive toxicity studies revealed that the methanol extract from T. equestre had no harmful effects on non-target organisms. The suitability index (SI) or predator safety factor (PSF) indicated that the methanol extract did not harm Poecilia reticulata Peters 1859, (predatory fish), Gambusia affinis S. F. Baird & Girard 1853, dragonfly nymph and Diplonychus indicus Venkatesan & Rao 1871 (water-bug). Gas chromatography-mass spectrometry (GCMS) analysis identified key compounds, including 3-butenenitrile, 2-methyl-(25.319%); 1-butanol, 2-nitro-(18.87%) and oxalic acid, heptyl propyl ester (21.82%) which may be responsible for the observed activity. Furthermore, the formulation based on the methanol extract demonstrated similar effectiveness against all treated mosquitoes at the laboratory level and was found to be non-toxic to mosquito predators. This groundbreaking research represents the first confirmation that methanol extract from T. equestre could be effectively employed in preventing mosquito-borne diseases through mosquito population control programs.

COMMUNITY PERSPECTIVE ON PREVENTION AND CONTROL STRATEGIES OF DENGUE INFECTION IN MALAYSIA

Dengue is a vector-borne disease caused by a rapidly-spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards control measures of mosquitoes and the utilisation of biocontrol. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: Knowledge of biological control, respondent profiles, knowledge of dengue fever prevention, and the utilisation of insecticide for mosquito control. Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and ABATE (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel and successful community programmes is significantly influenced by the perception of control measures for mosquitoes.

COMMUNITY PERSPECTIVE ON PREVENTION AND CONTROL STRATEGIES OF DENGUE INFECTION IN MALAYSIA

Dengue is a vector-borne disease caused by a rapidly-spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards control measures of mosquitoes and the utilisation of biocontrol. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: Knowledge of biological control, respondent profiles, knowledge of dengue fever prevention, and the utilisation of insecticide for mosquito control. Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and ABATE (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel and successful community programmes is significantly influenced by the perception of control measures for mosquitoes.

Guppy Fish (Poecilia reticulata) Behavior and Growth Are Affected by Variations in Light Color

This study aims to determine the effect of different colors of light on the behavior and growth of guppy fish (Poecilia reticulata). This research was conducted experimentally using a completely randomized design (CRD) with four treatments and five replications. The treatment used was treatment A with a white light color, treatment B with a red light color, treatment C with a yellow light color, and treatment D with a blue light color. The parameters observed were growth in absolute weight, fish behavior, and water quality (temperature and pH). Data analysis with One Way Anova and further test with LSD using SPSS 25. Based on the statistical hypothesis test with One Way ANOVA showed F count (3.828) &gt; F table (3.24) 5% level for guppy fish growth parameters so that the results are the effect of different light colors on the growth of guppy fish in each treatment. Fish behavior in all treatments gave a positive phototaxis response. The quality of the water in the experimental medium was within acceptable limits for guppy fish cultivation, 26-28°C for water temperature and 7 for the degree of acidity (pH) of water.

Evolutionary divergence of developmental plasticity and learning of mating tactics in Trinidadian guppies.

Behavioural plasticity is a major driver in the early stages of adaptation, but its effects in mediating evolution remain elusive because behavioural plasticity itself can evolve. In this study, we investigated how male Trinidadian guppies (Poecilia reticulata) adapted to different predation regimes diverged in behavioural plasticity of their mating tactic. We reared F2 juveniles of high- or low-predation population origins with different combinations of social and predator cues and assayed their mating behaviour upon sexual maturity. High-predation males learned their mating tactic from conspecific adults as juveniles, while low-predation males did not. High-predation males increased courtship when exposed to chemical predator cues during development; low-predation males decreased courtship in response to immediate chemical predator cues, but only when they were not exposed to such cues during development. Behavioural changes induced by predator cues were associated with developmental plasticity in brain morphology, but changes acquired through social learning were not. We thus show that guppy populations diverged in their response to social and ecological cues during development, and correlational evidence suggests that different cues can shape the same behaviour via different neural mechanisms. Our study demonstrates that behavioural plasticity, both environmentally induced and socially learnt, evolves rapidly and shapes adaptation when organisms colonize ecologically divergent habitats.

Evaluating the Longitudinal Connectivity of Dorim Stream in Seoul based on Artificial Constructure and Fish Data

The vertical connectivity of the river aquatic ecosystem was evaluated based on fish and artificial structures in Dorim stream, an urban stream in Seoul. As a result of a survey in the downstream area in 100.0 m of a total of 71 artificial structures, 13,728 individuals of fishes belonging to five orders, seven families, and 25 species were investigated, with the dominant species Zacco platypus and the subdominant species Rhynchocypris oxycephalus. As for endemic species, seven species were investigated and in terms of feeding characteristics, omnivorous species were the most common with 17 species (68%). Also an alien species, Poecilia reticulata was found. Fish species tended to decrease as the survey was conducted to upstream. Based on the movement characteristics of the fish species and the features of artificial structure survey results, the longitudinal continuity of each artificial structure was evaluated as 43 continuity, two damaged, 19 discontinuity, and seven absent. In inclined structures, stream velocity was found to be the main factor for discontinuity. In vertical structures, the down depth and head drop appeared to be the main factors for discontinuity. The results of this survey are expected to serve as basic data for the conservation of river aquatic ecosystems in the future.

On closer inspection: Reviewing the debate on whether fish cooperate to inspect predators

AbstractCooperative behaviours, which benefit a recipient, are widespread in the animal kingdom; yet their evolution is not straightforward. Reciprocity, i.e., cooperating with previously experienced cooperative partners, has been suggested to underly cooperation, but has been contested throughout the years. Once a textbook example of reciprocity was cooperative predator inspection, where one or several individuals leave their group to approach a potential threat. Each can at any point stop or retreat, increasing the risk for its partner. It was suggested that inspecting individuals follow a specific reciprocal strategy called tit‐for‐tat, i.e., cooperating on the first move and then copying the partner's last move. Numerous studies provide evidence to support the claim that fish cooperate to inspect predators, including three‐spined sticklebacks (Gasterosteus aculeatus), guppies (Poecilia reticulata) and minnows (Phoxinus phoxinus). However, over the past few decades some scholars have expressed scepticism whether predator inspection is indeed a cooperative behaviour or rather a case of by‐product mutualism, which describes behaviours that benefit a partner as a corollary of an otherwise selfish behaviour. For instance, it has been shown that pairs of fish moving in unfamiliar environments appear to coordinate movements even in the absence of predators. Many studies have also used coarse measures of overall approach rates towards predators rather than the fine‐grained analyses necessary to infer tit‐for‐tat in cooperative inspections. Now is the time to return to the question of cooperative predator inspection with new tools and approaches to resolve a decades‐old debate.