Search

Animals often moderate behaviours based on environmental and social cues to enhance their chances of survival and reproductive success. This requires reliable cues that reflect changes in ambient conditions. Environmental pollutants can increase communication costs and distort the accuracy of received information, leading to negative effects on the outcome of behavioural adjustments. Consequently, selection may reduce behavioural plasticity to avoid errors or promote more prudent decision making when certain cues become unreliable. In aquatic ecosystems, water turbidity shows high levels of natural variation, but human activities amplify its magnitude and extent by increasing algae and suspended solids in the water. Here, we investigated how elevated levels of water turbidity affected mating decisions made by female guppies in a laboratory setting. Guppies are a widespread species with a broad tolerance of polluted environments, and females rely heavily on visual cues when making mate choice decisions. We manipulated turbidity by adding suspended solids to water and tested how this affected female preference for males with more orange coloration. We found that females spent more time near males with a greater area of orange coloration in low turbidity water, but that this preference disappeared in both the mid and high turbidity water treatments. Moreover, female preferences were repeatable in low turbidity water and high turbidity water but not in mid turbidity water. Together, our results suggest that water turbidity impairs the ability of females to discern male coloration and affects the consistency of mate preferences. This could have consequences for the evolution of male coloration in turbid waters. • Male guppies have vibrant colour patterns indicating quality. • We investigated how water turbidity affects mating decisions by female guppies. • Females preferred to associate with more colourful males in low turbidity water. • Increased turbidity resulted in no preference for more colourful males. • Female mate preference was not repeatable in mid turbidity water. [ABSTRACT FROM AUTHOR]

Heterospecific sociability could enhance invasion success in social species since social non‐natives usually belong to small founding populations during the early stages of invasion. The twospot livebearer (Pseudoxiphophorus bimaculatus) is native to Central America and southern Mexico and is recently recognised as invasive in the Mexican Central Plateau, where it poses a threat to native species. Here, we evaluated twospot livebearer sociability towards either a conspecific pair or a shoal of four fish with one of four possible compositions, all conspecifics or two conspecifics combined with either two guppies, two porthole livebearers or two twoline skiffias. In a second experiment, foraging time, latency to feed, first fish to begin foraging and aggressive interactions were recorded under the same social conditions used in the sociability experiment, with body size included as a covariate in both experiments. All focal twospot livebearers spent significantly more time with the given shoals rather than with the available space in the aquarium. They showed a higher tendency to associate with small shoals of conspecifics than with pairs. Larger twospot livebearers associated more, regardless of the social condition. Twospot livebearer fed more with porthole livebearers, less with guppies and similarly with twoline skiffias. Latency to forage did not vary significantly between social conditions. Twospot livebearers were involved in more aggressive interactions when with guppies or porthole livebearers than when with native twoline skiffias or conspecifics. Twospot livebearers could gain benefits from associating with natives and conspecifics, but not with other invasive poeciliids. Heterospecific shoaling behaviour with natives may enhance invasion success during early stages when conspecifics are scarce while associating with other invasive poeciliids could lead to increased competition. Further research is needed on heterospecific interactions of non‐natives to better understand their behavioural role in invasion likelihood. [ABSTRACT FROM AUTHOR]

As cosmological simulations have grown in size, the permanent storage requirements of their particle data have also grown. Even modest simulations present a major logistical challenge for the groups which run these boxes and researchers without access to high performance computing facilities often need to restrict their analysis to lower quality data. In this paper, we present guppy , a compression algorithm and code base tailored to reduce the sizes of dark matter-only cosmological simulations by approximately an order of magnitude. guppy is a 'lossy' algorithm, meaning that it injects a small amount of controlled and uncorrelated noise into particle properties. We perform extensive tests on the impact that this noise has on the internal structure of dark matter haloes, and identify conservative accuracy limits which ensure that compression has no practical impact on single-snapshot halo properties, profiles, and abundances. We also release functional prototype libraries in C, Python, and Go for reading and creating guppy data. [ABSTRACT FROM AUTHOR]

Dispersal is critical to population persistence, colonization and connectivity which are all critical components of invasive success. While individual propensity to disperse varies within populations, the underlying mechanisms promoting individual dispersal remain unclear. Collectively, dispersal is influenced by the environment and individual phenotype. Here we investigated individual dispersal propensity in the Trinidadian guppy, Poecilia reticulata , and related individual variation in dispersal behaviour to phenotype and social/environmental conditions. Namely, we addressed the effect of sex ratio (social/environmental factor) on the tendency for individuals to disperse across physical barriers via jumping behaviour. Jumping is vital for the dispersal of many aquatic species and has been anecdotally linked to the guppy's global invasive success. We found similar jumping behaviour for males and females, with population sex ratio not influencing the magnitude of male or female dispersal. Further, we found consistent among-individual variation in jumping probability; individual differences explained 17.46% and 7.92% of total variation in jumping probability for males and females, respectively. These results strongly indicate that sex ratio does not influence jumping behaviour, suggesting that species invasions are mediated by a nonrandom subset of individuals with greater dispersal tendencies. Overall, this study stresses the need to move the focus of invasion biology from the species level to incorporate information on individual variation in behaviour. • Guppies differ in individual propensity to disperse over physical barriers. • Sex ratio does not influence jumping behaviour. • Species invasions are mediated by individuals with greater dispersal tendencies. [ABSTRACT FROM AUTHOR]

The guppy, Poecilia reticulata, is one of the most common cultured ornamental fish species, and a popular pet fish highly desired by hobbyists worldwide due to its availability of many brilliantly coloured fish of many varieties. The susceptibility of guppies to diseases presents a remarkable concern for both breeders and hobbyists. In this study, we report the emergence of disease in fancy guppies caused by a previously uncharacterized virus in the USA. This virus was isolated from moribund guppies in two separate outbreaks in California and Alabama, from December 2021 to June 2023. The infected guppies presented with acute morbidity and mortality shortly after shipping, displaying nonspecific clinical signs and gross changes including lethargy, anorexia, swimming at the water surface, gill pallor, mild to moderate coelomic distension and occasional skin lesions including protruding scales, skin ulcers and hyperaemia. Histological changes in affected fish were mild and nonspecific; however, liver and testes from moribund fish were positive for Tilapia lake virus (TiLV), the single described member in the family Amnoonviridae, using immunohistochemistry and in situ hybridization, although the latter was weak. A virus was successfully recovered following tissue inoculation on epithelioma papulosum cyprini and snakehead fish cell lines. Whole genome sequencing and phylogenetic analyses revealed nucleotide and amino acid homologies from 78.3%–91.2%, and 78.2%–97.7%, respectively, when comparing the guppy virus genomes to TiLV isolates. Based on the criteria outlined herein, we propose the classification of this new virus, fancy tailed guppy virus (FTGV), as a member of the family Amnoonviridae, with the name Tilapinevirus poikilos (from the Greek 'poikilos', meaning of many colours; various sorts, akin to 'poecilia'). [ABSTRACT FROM AUTHOR]

Environmental change can alter predator-prey dynamics. However, studying predators in the context of co-occurring environmental stressors remains rare, especially under field conditions. Using in situ filming, we examined how multiple stressors, including temperature and turbidity, impact the distribution and behaviour of wild fish predators of Trinidadian guppies (Poecilia reticulata). The measured environmental variables accounted for 17.6% of variance in predator species composition. While predator species differed in their associations with environmental variables, the overall prevalence of predators was greatest in slow flowing, deeper, warmer and less turbid habitats. Moreover, these warmer and less turbid habitats were associated with earlier visits to the prey stimulus by predators, and more frequent predator visits and attacks. Our findings highlight the need to consider ecological complexity, such as co-occurring stressors, to better understand how environmental change affects predator-prey interactions. Field observations show that fish predators exhibit stronger association with warmer, still, clear waters. Here they exert heightened predation pressure on prey fish, highlighting the importance of ecological context in predator-prey dynamics. [ABSTRACT FROM AUTHOR]

For many mammalian and avian species, it has been proposed that cognitive enrichment, such as puzzle feeders, can improve welfare in captive conditions. A well‐established method to evaluate the need for cognitive enrichment is to observe the preference of the animal between freely available food and a puzzle feeder. We investigated this preference in a teleost fish, the guppy. In most of our experimental trials, guppies first chose the feeder with freely available food over the puzzle feeder, in contrast with what was observed in most other species. Nevertheless, the guppies' number of choices for the puzzle feeder was significantly greater than zero. Moreover, after consuming the freely available food, most of the guppies tackled the puzzle feeder. This pattern of results suggests that guppies displayed a certain interest in the puzzle feeder that was overshadowed by their strong attraction towards the free food. Interestingly, several measures of performance indicated that female guppies responded more positively towards the puzzle feeder as compared to the males, suggesting sex differences in the preference for cognitive enrichment. In conclusion, our study highlights the potential significance of cognitive enrichment for captive fish. Considering that the number of individual fish maintained in captivity exceeds by far that of any other vertebrate group, it is paramount to investigate cognitive enrichment in other teleost species. [ABSTRACT FROM AUTHOR]

The presence of bystanders can influence the behavior of a forager, which has mainly been studied in primates and birds. We tested the effect of the absence and presence of an unfamiliar audience (females, males, and their combination) near or far from a food patch on the foraging behavior of guppies (Poecilia reticulata). Our investigation includes both males and females, recognizing that different social dynamics and reproductive strategies between the sexes could lead to varied responses to audience effects. For each focal fish, we measured the latency to start feeding, bite frequency, time spent near the audience, and overall mobility. Both males and females started feeding faster when food was close to any audience type. Specifically, females exhibited a faster feeding response in the presence of a female audience. Males reduced their feeding rate in the presence of male and mixed audiences, while both sexes increased their consumption when food was close to the audience. Focal fish, irrespective of their sex, spent more time in the vicinity of the audience zone when the audience was present, but surprisingly, females spent less time with a female audience compared to others. Only females increased their mobility when the food patch was far from any audience. Here, we show that guppies adjust their foraging behavior in the presence of an audience. The specific responses observed varied between the sexes, reflecting the distinct social trade-offs faced by each sex. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Several factors influence whether an organism remains in its local habitat. Parasites can, for example, influence host movement by impacting their behavior, physiology, and morphology. In rivers, fish that swim efficiently against the current are able to maintain their position without being displaced downstream, a behavior referred to as positive rheotaxis. We hypothesized that both the presence and number of ectoparasites on a host would affect the ability of fish to avoid downstream displacement and thus prevent them from remaining in their habitat. We used the guppy‐Gyrodactylus host‐ectoparasite model to test whether parasite presence and parasite load had an effect on fish rheotaxis. We quantified rheotaxis of sham‐infected and parasite‐infected fish in a circular flow tank in the laboratory prior to infection and 5–6 days postinfection. Both parasite‐infected and sham‐infected individuals expressed similar levels of positive rheotaxis prior to infection and after infection. However, with increasing parasite numbers, guppies covered less distance in the upstream direction and spent more time in slower flow zones. These results suggest that higher numbers of Gyrodactylus ectoparasites negatively influence rheotactic movements. Further research is needed to understand the ecological and evolutionary implications of this ectoparasite on fish movement. [ABSTRACT FROM AUTHOR]

Background: Exotic and ornamental fish are highly popular companion animals resulting in a significant transcontinental trade of fish, invertebrates and aquatic plants. A major issue is the diseases associated with these organisms, as they have a major impact on health of the fish in both public and private household aquaria. A secondary issue is the trade with these products, which potentially may expand the distribution area and spread a range of diseases to new habitats. Results: We here describe how Poecilia reticulata (guppy), produced in a private household aquarium, were invaded by cercariae of an exotic trematode released by imported Melanoides tuberculata snails. The fish presented with severe clinical signs (tremor, flashing, scraping of body against objects). A standard parasitological examination and morphometric identification showed scale pocket infections with a digenean trematode species within the genus Transversotrema. Molecular identification by PCR, sequencing and phylogenetic analyses of a 2646 bp sequence encoding ribosomal RNA (partial 18 S, ITS1, 5.8 S, ITS2, partial 28 S) was performed. The 1107 bp sequence of mitochondrial DNA (cox1) showed that the parasite differed from previously described Transversotrema species in M. tuberculata. Morphometrics of adult and larval specimens of this isolate also differed from previously described freshwater species within the genus. The new species was described and is named after Copenhagen, for its geographic origin. Conclusions: The genus Transversotrema comprises a range of species, adapted to a microhabitat in scalepockets of teleosts. A combination of morphological and molecular characterization techniques has been shown to provide a good differentiation between species. The fish were not purchased from a pet shop but produced in the home aquarium. This indicated that an infection pressure existed in the aquarium, where the source of infection was found to be exotic intermediate host snails M. tuberculata, which originally were imported and purchased from a pet shop. The potential spread of fish diseases associated with trade of fish and snails to new geographic regions, where climate conditions are favourable, is discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

One hundred and twenty red fantail male guppies (Poecilia reticulata) with an average weight of 0.64 ± 0.07 g were fed ad libitum a control diet without any herbals (0), 20 g/kg garlic, 20 g/kg red onion, and 20 g/kg sweet red pepper powders in 12 circular tanks for 60 d. The herbal treatments had significantly higher weight gain (94.70 ± 0.89 to 96.26 ± 0.90%), protein (3.58 ± 0.05 to 3.72 ± 0.06 mg/ml), ACH50 (1.41 ± 0.00 to 1.56 ± 0.00 U/ml), Ig (0.16 ± 0.00 to 0.32 ± 0.02 mg/ml), lysozyme activity (60.33 ± 0.88 to 68.00 ± 1.15 U/ml), carotenoids in lateral skin body (5.75 ± 0.025 to 8.26 ± 0.003 µg/g), and caudal fin (6.49 ± 0.003 to 10.10 ± 0.005 µg/g) than the control. Therefore, dietary garlic and sweet red pepper can be used for immunity and coloration in red fantail male guppies. [ABSTRACT FROM AUTHOR]

Cooperative 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. [ABSTRACT FROM AUTHOR]

Evolutionary biologists have long been interested in parsing out the roles of genetics, plasticity and their interaction on adaptive trait divergence. Since males and females often have different ecological and reproductive roles, separating how their traits are shaped by interactions between their genes and environment is necessary and important. Here, we disentangle the sex-specific effects of genetic divergence, developmental plasticity, social learning and contextual plasticity on foraging behaviour in Trinidadian guppies (Poecilia reticulata) adapted to high- or low-predation habitats. We reared second-generation siblings from both predation regimes with or without predator chemical cues, and with adult conspecifics from either high- or low-predation habitats. We then quantified their foraging behaviour in water with and without predator chemical cues. We found that high-predation guppies forage more efficiently than low-predation guppies, but this behavioural difference is context-dependent and shaped by different mechanisms in males and females. Higher foraging efficiency in high-predation females is largely genetically determined, and to a smaller extent socially learned from conspecifics. However, in high-predation males, higher foraging efficiency is plastically induced by predator cues during development. Our study demonstrates sex-specific differences in genetic versus plastic responses in foraging behaviour, a trait of significance in organismal fitness and ecosystem dynamics. [ABSTRACT FROM AUTHOR]

Behavioural plasticity allows organisms to respond to environmental challenges on short time scales. But what are the ecological and evolutionary processes that underlie behavioural plasticity? The answer to this question is complex and requires experimental dissection of the physiological, neural and molecular mechanisms contributing to behavioural plasticity as well as an understanding of the ecological and evolutionary contexts under which behavioural plasticity is adaptive. Here, we discuss key insights that research with Trinidadian guppies has provided on the underpinnings of adaptive behavioural plasticity. First, we present evidence that guppies exhibit contextual, developmental and transgenerational behavioural plasticity. Next, we review work on behavioural plasticity in guppies spanning three ecological contexts (predation, parasitism and turbidity) and three underlying mechanisms (endocrinological, neurobiological and genetic). Finally, we provide three outstanding questions that could leverage guppies further as a study system and give suggestions for how this research could be done. Research on behavioural plasticity in guppies has provided, and will continue to provide, a valuable opportunity to improve understanding of the ecological and evolutionary causes and consequences of behavioural plasticity. [ABSTRACT FROM AUTHOR]

Environmental influences on species' functional traits are important ecological issues to assess biodiversity. Relationships among fish abundance, their functional traits, and environmental conditions across different levels of anthropogenic impacts in a tropical Brazilian river were evaluated. We combined RLQ and fourth-corner methods, utilizing local environmental variables and the Human Footprint Index (HFI) as a human activities indicator. Three HFI levels (High, Intermediate, and Low) and short-term (1993–2009) impact changes at each location were assigned. Fish with internal fertilization and small body sizes were strongly associated with high HFI scores. Grass-dominated riparian areas were common in altered locations, whereas less altered localities exhibited the riparian cover dominated by trees. Highly altered areas showed high HFI, grass-covered riparian zones, and small-sized species with internal fertilization (e.g., Cyprinodontiformes like Poecilia vivipara, Poecilia reticulata, and Phalloceros caudimaculatus). In contrast, less altered areas had tree-lined riparian zones and medium to large-sized species with external fertilization and diverse traits. Underlying deterministic processes shape species distribution, tied to environment and traits. Filtering of traits in the most altered locations may favor small-sized species with internal fertilization. This approach, utilizing HFI and local variables to assess trait–environment relationships of riverine fish, facilitates understanding organisms' responses to environmental constraints. [ABSTRACT FROM AUTHOR]

The high-elevation plateaus of the inter-Andean valleys are home to shallow lakes that have become eutrophic. These lakes share similarities with shallow lakes in temperate and subtropical areas. Because native species diversity is low, invasive species dominate the fish and macrophytes communities. The study aimed to investigate the behavioral response of the local Daphnia pulex from the Andean shallow Lake Yahuarcocha to the exotic submerged macrophyte Egeria densa and the exotic fish Poecilia reticulata. Laboratory habitat choice experiments revealed that D. pulex from Lake Yahuarcocha strongly avoid E. densa, irrespective of the presence of the fish P. reticulata or chemical cues indicating fish predation on D. pulex. This observation could be explained by the fact that P. reticulata displayed a strong attraction to E. densa during the daytime, probably to avoid bird predation. D. pulex from the nearby Lake San Pablo where P. reticulata is absent but where the fish community is dominated by Oncorhynchus mykiss displayed the same avoidance behavior to submerged macrophytes as D. pulex from Lake Yahuarcocha. These results indicate that macrophytes in these high-elevation shallow lakes may not facilitate top-down control of phytoplankton, since plants do not offer refuge to D. pulex from fish predation. [ABSTRACT FROM AUTHOR]

Classic evolutionary theory predicts that predation will shift trait means and erode variance within prey species; however, several studies indicate higher behavioral trait variance and trait integration in high-predation populations. These results come predominately from field-sampled animals comparing low- and high-predation sites and thus cannot isolate the role of predation from other ecological factors, including density effects arising from higher predation. Here, we study the role of predation on behavioral trait (co)variation in experimental populations of guppies (Poecilia reticulata) living with and without a benthic ambush predator (Jaguar cichlid) to better evaluate the role of predation and where density was equalized among replicates twice per year. At 2.5 years after introduction of the predators (∼10 overlapping generations), 40 males were sampled from each of the six replicate populations and extensively assayed for activity rates, water column use, and latency to feed following disturbance. Individual variation was pronounced in both treatments, with substantial individual variation in means, temporal plasticity, and predictability (inverse residual variance). Predators had little effect on mean behavior, although there was some evidence for greater use of the upper water column in predator-exposed fish. There was greater variance among individuals in water column use in predator-exposed fish, and they habituated more quickly over time; individuals higher in the water column fed slower and had a reduced positive correlation with activity, although again this effect was time specific. Predators also affected the integration of personality and plasticity—among-individual variances in water column use increased, and those in activity decreased, through time—which was absent in controls. Our results contrast with the extensive guppy literature showing rapid evolution in trait means, demonstrating either increases or maintenance of behavioral variance under predation. [ABSTRACT FROM AUTHOR]

Environmental 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. [ABSTRACT FROM AUTHOR]

Simple Summary: The housefly (Musca domestica) is a global vector of several pathogens and a nuisance to humans and animals. Repellents reduce the risk of housefly vector diseases. Green repellents from plant essential oils (EOs) and their active compounds were, at the time, a promising option against houseflies. This study evaluated the housefly-repellent activities of every tested EO, their main constituents, and several combinations of them. The combinations were lemongrass (Cymbopogon citratus) EO + trans-anethole, lemongrass EO + star anise (Illicium verum) EO, geranial + trans-anethole, and star anise EO + geranial. The efficacies of every formulation were compared against each other and DEET (a synthetic repellent). All combinations were more effective in repellency than all single-component formulations and DEET. More significantly, all of them were safe for four non-target species: guppy (Poecilia reticulata), molly (Poecilia latipinna), dwarf honeybee (Apis florea), and stingless bee (Tetragonula pagdeni). These combinations could be developed into valuable green repellents for housefly vector disease management. The present study evaluated the housefly repellency of single-component formulations and combinations of lemongrass and star anise essential oils (EOs) and their main constituents. The efficacies of the combinations were compared against those of single-component formulations and DEET. Safety bioassays of all formulations and DEET on non-target species—guppy, molly, dwarf honeybee, and stingless bee—were conducted. GC–MS analysis showed that the main constituent of lemongrass EO was geranial (46.83%) and that of star anise EO was trans-anethole (92.88%). All combinations were highly synergistic compared to single-component formulations, with an increased repellent value (IR) of 34.6 to 51.2%. The greatest synergistic effect was achieved by 1.0% lemongrass EO + 1.0% trans-anethole combination, with an IR of 51.2%. The strongest, 100% repellent rate at 6 h was achieved by 1.0% geranial + 1.0% trans-anethole. They were twice as effective as DEET and caused obvious damage to housefly antennae under microscopic observation. All single-component formulations and combinations were benign to the four tested non-target species. In contrast, DEET was highly toxic to them. The synergistic repellency and biosafety of these two combinations are compellingly strong support for developing them into an effective green repellent. [ABSTRACT FROM AUTHOR]

The research aimed to analyze the influences of adding marine green algae Chaetomorpha aerea to the diet of guppy fish (Poecillia reticulate) on growth, immunological responses in skin mucus, total carotenoid content, and sexual characteristics. A total of 450 fish, with a mean body weight of 0.19 ± 0.1 g and 30 fish per tank (triplicate), were randomly fed into 15 experimental tanks, each containing 50 L. Five different diets with 0, 1, 2, 4, 8, and 10% of C. aerea g/kg diets were fed to P. reticulate for 30 days. After 30 days, growth, immunological responses in skin mucus, total carotenoid content, and sexual characteristics were investigated. The results observed that the feed conversion rate and fry output were significantly (p > 0.05) decreased in experimental groups compared to the control group. The results revealed that the dietary inclusion of C. aerea algal significantly increased (p < 0.05) in mucosal immunological parameters containing lysozyme activity, myeloperoxidase activity, total immunoglobulins, and alternative complement activity, which were the highest in the group with 4% of C. aerea g/kg. Additionally, lateral skin and the caudal fin of fish had higher total carotenoid levels from the dietary C. aerea algae diet than the control group, which were the highest in the groups with 4%. Among them, 4 and 8% of C. aerea g/kg diet resulted in better growth performance and feed conversion ratio. Thus, the study suggested that 4% of C. aerea g/kg diet has enrichment of immunity, total carotenoid concentrations, and skin mucus immunity of P. reticulate. [ABSTRACT FROM AUTHOR]

Guppies are small tropical fish with brightly colored bodies and variable tail shapes. There are two phenotypes of domestic guppy eye color: red and black. The wild type is black-eyed. The main object of this study was to identify candidate genes for the red-eyed phenotype in domestic guppies. We hope to provide molecular genetic information for the development of new domestic guppy strains. Additionally, the results also contribute to basic research concerning guppies. In this study, 121 domestic guppies were used for genomic analysis (GWAS), and 44 genes were identified. Furthermore, 21 domestic guppies were used for transcriptomic analysis, and 874 differentially expressed genes (DEGs) were identified, including 357 upregulated and 517 downregulated genes. Through GO and KEGG enrichment, we identified some important terms or pathways mainly related to melanin biosynthesis and ion transport. qRT-PCR was also performed to verify the differential expression levels of four important candidate genes (TYR, OCA2, SLC45A2, and SLC24A5) between red-eyed and black-eyed guppies. Based on the results of genomic and transcriptomic analyses, we propose that OCA2 is the most important candidate gene for the red-eyed phenotype in guppies. [ABSTRACT FROM AUTHOR]

There is a growing concern regarding the adverse risks exposure to cylindrospermopsin (CYN) might exert on animals and humans. However, data regarding the toxicity of this cyanotoxin to neotropical fish species are scarce. Using the fish species Poecilia reticulata, the influence of CYN concentrations equal to and above the tolerable for drinking water may produce on liver was determined by assessing biomarkers of antioxidant defense mechanisms and correlated to qualitative and semiquantitative histopathological observations. Adult females were exposed to 0.0 (Control); 0.5, 1 and 1.5 µg/L pure CYN for 24 or 96 hr, in triplicate. Subsequently the livers were extracted for biochemical assays and histopathological evaluation. Catalase (CAT) activity was significantly increased only by 1.5 µg/L CYN-treatment, at both exposure times. Glutathione -S-transferase (GST) activity presented a biphasic response for both exposure times. It was markedly decreased after exposure by 0.5 µg/L CYN treatment but significantly elevated by 1.5 µg/L CYN treatment. All CYN treatments produced histopathological alterations, as evidenced by hepatocyte cords degeneration, steatosis, inflammatory infiltration, melanomacrophage centers, vessel congestion, and areas with necrosis. Further, an IORG >35 was achieved for all treatments, indicative of the presence of severe histological alterations in P. reticulata hepatic parenchyma and stroma. Taken together, data demonstrated evidence that CYN-induced hepatotoxicity in P. reticulata appears to be associated with an imbalance of antioxidant defense mechanisms accompanied by histopathological liver alterations. It is worthy to note that exposure to low environmentally-relevant CYN concentrations might constitute a significant risk to health of aquatic organisms. [ABSTRACT FROM AUTHOR]

Increased exposure to pathogens is often considered to be one of the most significant costs of group living. As a result, animals typically avoid close association with individuals who manifest symptoms of disease. The question remains, however, whether avoidance behaviors are mediated by effects relating specifically to the disease itself, or through recognition of more general sickness behaviors that emerge from the activity of the immune system in response to infection. Here we examined the effects of an immune challenge, induced through exposure to bacterial lipopolysaccharides (LPS), on individual and social behavior in female guppies (Poecilia reticulata). We found that in a binary choice presentation, healthy focal individuals showed a strong preference to associate with stimulus shoals of saline-injected fish rather than stimulus shoals of LPS-injected fish. In a subsequent examination of group-level dynamics, shoals of LPS-injected females were more dispersed than similar shoals comprised of control fish and showed less coherent collective behavior despite the lack of any obvious difference in general activity between LPS and control fish. We discuss these findings in relation to the need for social animals to mitigate the risk of disease that is associated with living in proximity to conspecifics. [ABSTRACT FROM AUTHOR]

Although visual sexual signals, such as ornamental colors and courtship displays, and large body size in males are attractive to females in numerous species, they may also inadvertently attract the attention of eavesdropping predators and thus may be costly in terms of increasing individual risk of mortality to predation. Theoretically, more color ornamented and larger males should be more predation threat sensitive and suppress their sexual signaling and(or) mating effort relatively more than their less color ornamented and smaller counterparts when under predation hazard. Here, we experimentally tested this hypothesis by quantifying concurrently the rates of alternative mating tactics (courtship displays, sneak mating attempts) expressed by male Trinidadian guppies (Poecilia reticulata) varying in color ornamentation and body size under a staged immediate threat of predation. Males suppressed their overall mating effort in response to the perceived predation threat, decreasing the frequency of their (presumably more conspicuous) courtship displays significantly more on average than the frequency of their sneak mating behavior. Statistically controlling for body length, more color-ornamented males were more threat sensitive in their courtship displays, but not sneak mating attempts, under predation hazard than drabber males. Controlling for body coloration, larger males exhibited lower courtship and sneak mating efforts than smaller males in both predation treatments, but body length only influenced threat sensitivity in sneak mating behavior. These results are consistent with both the threat sensitive hypothesis and asset protection principle and highlight the phenotype dependency and adaptive plasticity of alternative mating tactics in male guppies under varying predation risk. [ABSTRACT FROM AUTHOR]

Simple Summary: Fertility, in males and females, is linked to the correct formation of sexual line cells (spermatozoa and oocytes) through a physiological process called meiosis. In all vertebrates, meiosis is orchestrated by different molecular effectors, and among these, we focused our attention on CLASP2, a protein involved in cytoskeleton function. In several animal models, such as mice, flies, or frogs, this protein is known to participate in spermatozoa maturation. However, in fish, nothing was known about the presence of CLASP2 in sexual organs or whether it could have a role in spermatozoa formation. To investigate this point, we used two excellent vertebrate aquatic models: guppy and zebrafish. Our results open a window to knowledge about male sex cell formation effectors in fish. Considering the great affinity between zebrafish and humans, the study of CLASP2 in fish spermatogenesis could uncover a new target of male fertility in humans. Cytoplasmic linker-associated protein-2 (CLASP2) is a member of the CLIP-associating proteins (CLASPs) family involved in the structure and function of microtubules and Golgi apparatus. Several studies performed using different mammalian and non-mammalian model organisms reported that CLASP2 controls microtubule dynamics and the organization of microtubule networks. In Drosophila and mice, an important role of CLASP2 during the development of germ cell lines has been uncovered. However, no study has clearly defined its role during fish germ cell differentiation. In the present study, we used two excellent aquatic animal models among teleost fish: zebrafish (Danio rerio) and guppy (Poecilia reticulata). Using qPCR, we found that the clasp2 transcript level is significantly high in the testis of both fish. Then, by in situ hybridization, we localized the clasp2 transcript in the spermatozoa of zebrafish and the spermatozeugmata of guppy. Our data suggest a potential role for this gene in the last stage of spermiogenesis in fish. [ABSTRACT FROM AUTHOR]

Among‐individual variation in cognitive traits, widely assumed to have evolved under adaptive processes, is increasingly being demonstrated across animal taxa. As variation among individuals is required for natural selection, characterizing individual differences and their heritability is important to understand how cognitive traits evolve. Here, we use a quantitative genetic study of wild‐type guppies repeatedly exposed to a 'detour task' to test for genetic variance in the cognitive trait of inhibitory control. We also test for genotype‐by‐environment interactions (GxE) by testing related fish under alternative experimental treatments (transparent vs. semi‐transparent barrier in the detour‐task). We find among‐individual variation in detour task performance, consistent with differences in inhibitory control. However, analysis of GxE reveals that heritable factors only contribute to performance variation in one treatment. This suggests that the adaptive evolutionary potential of inhibitory control (and/or other latent variables contributing to task performance) may be highly sensitive to environmental conditions. The presence of GxE also implies that the plastic response of detour task performance to treatment environment is genetically variable. Our results are consistent with a scenario where variation in individual inhibitory control stems from complex interactions between heritable and plastic components. [ABSTRACT FROM AUTHOR]

Parasitic infestations are one of the most concerning problems limiting ornamental fish farming. In addition to the direct economic losses due to the major mortalities, parasites may significantly negatively impact the body shape, coloration, growth rate, and health condition of the fish. The results of the study highlight the importance of comprehensive parasitological analysis in the diagnosis and treatment of parasitic infections in ornamental fish farms. The presence of multiple parasites in the affected fish emphasizes the need for effective biosecurity measures, such as extending the quarantine period for newly imported fish, closely monitoring fish populations, and implementing isolation units to prevent the spread of infections. By implementing these preventative measures, ornamental fish farmers can reduce the risk of parasitic infections and ensure the health and well-being of their fish populations. This, in turn, can lead to increased profitability and sustainability for their business. Overall, the current study aimed to conduct a clinical, histopathological, and phylogenetic analysis of the epibiont ciliated protozoan Epistylis wuhanensis and the copepod crustacean Lernaea cyprinacea in a freshwater ornamental fish farm in Iran. Furthermore, it provides valuable insights into the prevalence and impact of parasitic infections in ornamental fish farms and underscores the need for continued research and the development of effective preventative measures to address this issue. A total of 60 symptomatic freshwater ornamental fish, including 30 guppy (Poecilia reticulata) and 30 sailfin molly (Poecilia latipinna), were packed in polyethylene bags filled with oxygenated pond water and transported to the Ornamental Fish Clinic, Faculty of Veterinary Medicine, University of Tehran, for parasitological analysis. Following the clinical examination, histopathological analysis was performed on 10% NBF (neutral buffered formalin)-fixed samples from affected tissues, including the skin, skeletal muscle, and liver, to identify any pathological changes associated with the parasitic infections. Furthermore, the DNA was extracted from the 99% ethanol-fixed samples using a commercial DNA extraction tissue kit (SinaPure DNA, Iran), and PCR was performed using Peri18S-F1 (5′-ACC TGG TTG ATC CTG CCA GT-3′) and Peri18S-R1 (5′-TGC AGG TTC ACC TAC GGA AA-3′) (first reaction), and Peri18S-F2 (5′-CCG CGG TAA TTC CAG CTC-3′) and Peri18S-R2 (5′-GAT CCC CTA ACT TTC GTT CTT GA-3′) (second round) primers for the identified parasites. Finally, the PCR products were sequenced using Sanger dideoxy sequencing methods, and the resulting sequences were compared to sequences in the BLAST search program to provide a comprehensive picture of the current parasite-based disorder. The crustacean L. cyprinacea and the epibiont sessilid E. wuhanensis were identified in the examined ornamental guppy (6/30) and sailfin molly (6/30), with an overall parasitic prevalence of 20.00% (12/60). Ciliates were found in all tissue lesions but not in fish without lesions. A great number of the ciliated protozoan E. wuhanensis were found attached to the integumentary area of L. cyprinacea. Microscopically, oval to round granulomatous lesions were observed in cutaneous and skeletal muscles. Lymphoplasmacytic dermatitis and myositis were also observed. The crustacean L. cyprinacea serves as a mechanical vector for E. wuhanensis infection and spreads the disease in ornamental fish farming operations. For the first time in Iran, we successfully presented diagnostic morphological and molecular data on sessilids isolated from L. cyprinacea. Based on the findings of the current study, such parasitic infections may cause significant economic losses following invasion of the integument area of fish, eventually leading to death, if treatment is neglected or inadequate. Furthermore, the findings of the analysis were used to develop effective diagnostic approaches for the affected fish, as well as recommendations for improved health conditions to prevent future outbreaks of parasitic infections. However, further research is needed to determine the precise mechanisms of crustacean attachment and host-crustacean-peritrich protozoan interactions. Furthermore, the direct and indirect effects of various environmental factors on the emergence and spread of the current disease should be considered. [ABSTRACT FROM AUTHOR]

Predator–prey interactions are ubiquitous and under strong selection because of the consequences experienced by both predator and prey if they lose the interaction. Biomechanics and behavior play important roles in the outcome of these interactions, but many studies focus on the prey, restrict the range of behaviors considered, and the role of prey boldness in the outcome is not understood. We used high‐speed video to test for effects of multiple measures of performance and kinematics of both the predator and prey, and boldness of prey on the outcome of interactions between Pike Cichlids (Crenicichla sp.) and Guppies (Poecilia reticulata). We found high variation in the behaviors employed during the predator–prey interactions, including in suction versus raptorial feeding, strike accuracy, and guppy responsiveness. We also found that predators moving relatively slower and prey moving relatively faster were more successful at consuming the prey and evading the predator, respectively. Prey that reacted farther from the predator was more likely to escape predation, but boldness of the prey did not affect the interaction. Our work suggests that a high level of variation in predator–prey interactions is widespread, even when strike and escape behaviors are stereotyped. We also showed that what both the predator and the prey do during an interaction are important in determining the outcome. [ABSTRACT FROM AUTHOR]

Life‐history theory suggests that ageing is one of the costs of reproduction. Accordingly, a higher reproductive allocation is expected to increase the deterioration of both the somatic and the germinal lines through enhanced telomere attrition. In most species, males' reproductive allocation mainly regards traits that increase mating and fertilization success, that is sexually selected traits. In this study, we tested the hypothesis that a higher investment in sexually selected traits is associated with a reduced relative telomere length (RTL) in the guppy (Poecilia reticulata), an ectotherm species characterized by strong pre‐ and postcopulatory sexual selection. We first measured telomere length in both the soma and the sperm over guppies' lifespan to see whether there was any variation in telomere length associated with age. Second, we investigated whether a greater investment in pre‐ and postcopulatory sexually selected traits is linked to shorter telomere length in both the somatic and the sperm germinal lines, and in young and old males. We found that telomeres lengthened with age in the somatic tissue, but there was no age‐dependent variation in telomere length in the sperm cells. Telomere length in guppies was significantly and negatively correlated with sperm production in both tissues and life stages considered in this study. Our findings indicate that telomere length in male guppies is strongly associated with their reproductive investment (sperm production), suggesting that a trade‐off between reproduction and maintenance is occurring at each stage of males' life in this species. [ABSTRACT FROM AUTHOR]

The blackstripe livebearer Poeciliopsis prolifica is a live-bearing fish belonging to the family Poeciliidae with high level of postfertilization maternal investment (matrotrophy). This viviparous matrotrophic species has evolved a structure similarly to the mammalian placenta. Placentas have independently evolved multiple times in Poeciliidae from nonplacental ancestors, which provide an opportunity to study the placental evolution. However, there is a lack of high-quality reference genomes for the placental species in Poeciliidae. In this study, we present a 674 Mb assembly of P. prolifica in 504 contigs with excellent continuity (contig N50 7.7 Mb) and completeness (97.2% Benchmarking Universal Single-Copy Orthologs [BUSCO] completeness score, including 92.6% single-copy and 4.6% duplicated BUSCO score). A total of 27,227 protein-coding genes were annotated from the merged datasets based on bioinformatic prediction, RNA sequencing and homology evidence. Phylogenomic analyses revealed that P. prolifica diverged from the guppy (Poecilia reticulata) ∼19 Ma. Our research provides the necessary resources and the genomic toolkit for investigating the genetic underpinning of placentation. [ABSTRACT FROM AUTHOR]

Most studies on developmental variation in cognition have suggested that individuals are born with reduced or absent cognitive abilities, and thereafter, cognitive performance increases with age during early development. However, these studies have been mainly performed in altricial species, such as humans, in which offspring are extremely immature at birth. In this work, we tested the hypothesis that species with other developmental modes might show different patterns of cognitive development. To this end, we analysed inhibitory control performance in two teleost species with different developmental modes, the zebrafish Danio rerio and the guppy Poecilia reticulata, exploiting a simple paradigm based on spontaneous behaviour and therefore applicable to subjects of different ages. Zebrafish hatch as larvae 3 days after fertilisation, and have an immature nervous system, a situation that mirrors extreme altriciality. We found that at the early stages of development, zebrafish displayed no evidence of inhibitory control, which only begun to emerge after one month of life. Conversely, guppies, which are born after approximately one month of gestation as fully developed and independent individuals, solved the inhibitory control task since their first days of life, although performance increased with sexual maturation. Our study suggests that the typical progression described during early ontogeny in humans and other species might not be the only developmental trend for animals' cognition and that a species' developmental mode might determine variation in cognition across subjects of different age. [ABSTRACT FROM AUTHOR]

Invasive fish can profoundly affect communities they invade. In Hawai'i, invasive fishes have become established in many anchialine pools, threatening the persistence of resident invertebrates, including several endangered species. Tools to eradicate invasive fishes from these pools are lacking. This study tested the efficacy of carbon dioxide (CO2) gas diffused into anchialine pool water as a method to eradicate invasive Mozambique tilapia (Oreochromis mossambicus), guppies (Poecilia reticulata), and western mosquitofish (Gambusia affinis). We first conducted aquarium trials to identify how these fishes were affected by elevated CO2 and the concomitant reduction in pH. We then carried out field trials in pools containing these fish in one pool each at two national historical parks on the Island of Hawai'i during July 2021-January 2022. We also developed environmental DNA (eDNA) protocols to detect fish that may have survived CO2 treatments. The effect of CO2 on fish behavior varied among species; at pH 5.3 (CO2 = 255 mg/L) for tilapia and 5.0 (CO2 = 488 mg/L) for tilapia, guppies, and mosquitofish, all generally lost their ability to swim, showed slow or no gill movement, and altered their position in the water column. No tilapia survived the trials (n = 4 and 6 individuals at pH 5.3 and 5.0, respectively). In contrast, 41.7% (n = 12) of adult guppies and 66.7% (n = 12) of adult mosquitofish survived treatment at pH 5.0. In the field we were unable to reduce anchialine pool water pH below 5.7. Regardless, we were able to eradicate tilapia from one pool over four sequential treatments. Post-treatment eDNA assessments supported visual surveys, confirming our results. We were not able to eradicate guppies and mosquitofish. Results from this study show that CO2 can be an effective tool for eradicating invasive tilapia from anchialine pools, and post-treatment eDNA assessments can provide managers with a method for evaluating the success of eradication efforts. [ABSTRACT FROM AUTHOR]

Mutations are the primary source of all genetic variation. Knowledge about their rates is critical for any evolutionary genetic analyses, but for a long time, that knowledge has remained elusive and indirectly inferred. In recent years, parent–offspring comparisons have yielded the first direct mutation rate estimates. The analyses are, however, challenging due to high rate of false positives and no consensus regarding standardized filtering of candidate de novo mutations. Here, we validate the application of a machine learning approach for such a task and estimate the mutation rate for the guppy (Poecilia reticulata), a model species in eco‐evolutionary studies. We sequenced 4 parents and 20 offspring, followed by screening their genomes for de novo mutations. The initial large number of candidate de novo mutations was hard‐filtered to remove false‐positive results. These results were compared with mutation rate estimated with a supervised machine learning approach. Both approaches were followed by molecular validation of all candidate de novo mutations and yielded similar results. The ML method uniquely identified three mutations, but overall required more hands‐on curation and had higher rates of false positives and false negatives. Both methods concordantly showed no difference in mutation rates between families. Estimated here the guppy mutation rate is among the lowest directly estimated mutation rates in vertebrates; however, previous research has also found low estimated rates in other teleost fishes. We discuss potential explanations for such a pattern, as well as future utility and limitations of machine learning approaches. [ABSTRACT FROM AUTHOR]

Over recent decades, substantial research has focused on fish cognitive evolution to increase our understanding of the evolution of the enormous diversity of cognitive abilities that exists in fishes. One important but understudied aspect of cognitive evolution is sexual dimorphism in cognitive abilities. Sex-specific variation in brain region morphology has been proposed to be an important mechanism in this context. However, it is also common to find sex-specific variation in behavior and cognition without associated differences in brain morphology among the sexes. The telencephalon is the major cognitive center in the vertebrate brain and variation in telencephalon size has been associated with variation in cognition. Here, we utilize recently developed guppy artificial selection lines with ca. 10% differences in relative telencephalon size to investigate whether similar responses to selection of the size of this region may affect cognitive abilities differently in males and females. To that end, we compared two ecologically relevant aspects of cognition, detour learning and binary spatial discrimination. We tested the significance of the interaction between telencephalon size and sex, and we found no sex-specific effects of evolutionary increases in telencephalon size in the cognitive abilities tested. This study indicates that no clear cognitive sex-specific effects occur in response to rapid selection of telencephalon size. We suggest that future research on sexual dimorphism in cognitive abilities in fish could use various cognitive tests and examine telencephalic sub-regions to gain a more comprehensive understanding of their evolution. [ABSTRACT FROM AUTHOR]

The global rise of pharmaceutical contaminants in the aquatic environment poses a serious threat to ecological and evolutionary processes. Studies have traditionally focused on the collateral (average) effects of psychoactive pollutants on ecologically relevant behaviors of wildlife, often neglecting effects among and within individuals, and whether they differ between males and females. We tested whether psychoactive pollutants have sex-specific effects on behavioral individuality and plasticity in guppies (Poecilia reticulata), a freshwater species that inhabits contaminated waterways in the wild. Fish were exposed to fluoxetine (Prozac) for 2 years across multiple generations before their activity and stress-related behavior were repeatedly assayed. Using a Bayesian statistical approach that partitions the effects among and within individuals, we found that males—but not females—in fluoxetine-exposed populations differed less from each other in their behavior (lower behavioral individuality) than unexposed males. In sharp contrast, effects on behavioral plasticity were observed in females—but not in males—whereby exposure to even low levels of fluoxetine resulted in a substantial decrease (activity) and increase (freezing behavior) in the behavioral plasticity of females. Our evidence reveals that psychoactive pollution has sex-specific effects on the individual behavior of fish, suggesting that males and females might not be equally vulnerable to global pollutants. [ABSTRACT FROM AUTHOR]

This article explores the effects of human disturbance on predator inspection behavior in Trinidadian guppies. The study found that guppies exhibited higher inspection activity in disturbed locations compared to undisturbed locations. The increased uncertainty caused by anthropogenic disturbances may lead to guppies gathering more information about predation threats. The findings suggest that exposure to human disturbance increases uncertainty for guppies and that they may compensate for this uncertainty by increasing their reliance on information acquisition. Further research is needed to understand the precise ecological mechanisms at play. [Extracted from the article]

Background and Aim: Malaysia has more than 630 culturists who are involved in the ornamental fish industry and culture 250 species, including local and exotic species. Among these viruses, megalocytiviruses have been associated with severe systemic diseases and economic losses in ornamental fish. The intensity of Megalocytivirus infection in Pterophyllum scalare in Malaysia remains unknown. Thus, this study aimed to investigate the occurrence of Megalocytivirus while discovering its associated risk factors and the genotypes of its causative agents in an ornamental fish farm in Malaysia. Materials and Methods: Seven broodstock pairs of P. scalare were used in this study to follow the life stages of fish, from egg to market size. Water samples and other samples, such as mucus swabs, gill swabs, P. scalare eggs, fries, juveniles, snails, snail eggs, live feed (Tubifex worms and Moina spp.), sediment samples, and wild fish, were collected periodically for initial environmental sampling from day 0 to day 60. Nested polymerase chain reaction amplifications were performed for megalocytivirus-related sequences. The phylogenetic tree, including the sampled causative agents of megalocytiviruses, was inferred from the major capsid protein genes of all known Iridoviridae species. Pearson's correlation coefficients were calculated to determine the strength of the correlation between the presence of megalocytiviruses in P. scalare samples and the associated risk factors. Results: A total of 312 out of 935 pooled and individual samples tested positive for the presence of Megalocytivirus-related sequences, except snail eggs and wild fish (Poecilia reticulata). No clinical symptoms were observed in any fish samples. Megalocytivirus-associated viruses detected in water samples indicate horizontal transmission of the virus. All the nucleotide sequences found in this study had high nucleotide identities of 95%-99 % and were closely related to Megalocytivirus genotype I infectious spleen and kidney necrosis virus. Risk factors associated with Megalocytivirus include water temperature, dissolved oxygen (DO), pH, ammonia, nitrate, nitrite, and the life stages of P. scalare. High Megalocytivirus infection was detected when the water temperature, DO, and pH were high in P. scalare, high water temperature and nitrate in the water samples, and the same rate of Megalocytivirus infection in P. scalare fry and juveniles. Conclusion: This is the first study to confirm the existence of different possible routes of megalocytivirus distribution in ornamental fish farms in Malaysia. Nevertheless, the connection between the mode of transmission and the risk factors for this virus needs to be explored further to recognize the evolution and potential new host species. [ABSTRACT FROM AUTHOR]

Postcopulatory sexual selection (PCSS), namely sperm competition and cryptic female choice, is typically investigated in benign environments, with a fixed number of partners, which mate at the same time intervals; all conditions that are rarely met in natural populations.Although there is increasing evidence that environmental fluctuations affect sexual selection before mating, whether and to which extent they influence postcopulatory trajectories is still little explored.PCSS was investigated in replicate populations of guppies (Poecilia reticulata) in which males and females mated after maintained for 2 weeks on either restricted (RE) or ad libitum (AL) diet and the paternity of the offspring produced by multiply mated females was assigned using microsatellite markers.Compared to AL fish, RE females (i) had fewer mating partners, but the time interval between the first and the last mating was not affected; (ii) produced broods with a lower variance in male fertilization success (a measure of the opportunity for PCSS); and (iii) produced broods with a paternity bias towards the first mate (reversing the last sperm precedence observed in AL populations), and associated more towards males with higher courtship rate.Our results demonstrate that short‐term limitation in food availability significantly influence PCSS by modifying both fertilization success variance and sperm precedence pattern. Environmental variation should therefore become part of the research paradigm to improve our understanding of postcopulatory evolutionary dynamics. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

There are various mosquitos borne diseases playing major role of transmission as vector; these include dengue, malaria, filariasis and yellow fever. Various places around us everywhere act as breeding sites for different developmental stages of mosquitoes. Variety of chemicals are being used to control breeding and spread of mosquitoes which include mercuric chloride, phenols, Paris green cresols, naphthalene, Bordeaux mixture, calcium arsenate, rosin-fish oil soap, and nicotine sulfate which are prone to various risks on environment and biodiversity. In present study an alternative approach of control through insectivore fish Poecilia reticulata and Poecilia sphenops was used against mosquitoe's larvae as an alternative approach. The predation effect of insectivore fish on mosquito larvae (200) of culex and aedes was observed at different temperatures including 20°C, 25°C and 30°C for one hour duration and observation was recorded at 5 minutes interval. At 20°C the maximum consumption of larvae was observed at 35 minutes while for 25°C the maximum consumption was observed at 55 minutes similar results are observed at 30°C with increase of time for Poecilia reticulate. Poecilia sphenops also showed significant results at recorded temperatures. Also the morphometric parameters of mosquito's larvae are shown in results which gave significant results. This study gave a useful alternate for control of breeding sites of mosquitoes which can save mankind from various serious mosquitoes' related diseases. [ABSTRACT FROM AUTHOR]

Classic theory for density-dependent selection for delayed maturation requires that a population be regulated through some combination of adult fecundity and/or juvenile survival. We tested whether those demographic conditions were met in four experimental populations of Trinidadian guppies in which delayed maturation of males evolved when the densities of those populations became high. We used monthly mark-recapture data to examine population dynamics and demography in these populations. Three of the four populations displayed clear evidence of regulation. In all four populations, monthly adult survival rates were independent of biomass density or actually increased with increased biomass density. Juvenile recruitment, which is a combination of adult fecundity and juvenile survival, decreased as biomass density increased in all four populations. Demography showed marked seasonality, with greater survival and higher recruitment in the dry season than the wet season. Population regulation via juvenile recruitment supports the hypothesis that density-dependent selection was responsible for the evolution of delayed maturity in males. This body of work represents one of the few complete tests of density-dependent selection theory. [ABSTRACT FROM AUTHOR]

The 'good genes' hypothesis for the evolution of male secondary sexual traits poses that female preferences for such traits are driven by indirect genetic benefits. However, support for the hypothesis remains ambiguous, and, in particular, the genetic basis for the benefits has rarely been investigated. Here, we use seminatural populations of Trinidadian guppies to investigate whether sexually selected traits (orange, black and iridescent colouration, gonopodium length and body size) predict fitness measured as the number of grandoffspring, a metric that integrates across fitness components and sexes. Furthermore, we tested whether two potential sources of genetic benefits—major histocompatibility complex (MHC) genotypes and multilocus heterozygosity (MLH)—are significant predictors of fitness and of the size of sexually selected traits. We found a significant, nonlinear effect of the area of black pigmentation and male body size on the number of grandoffspring, suggesting stabilizing selection on black area, and nonlinear selection favouring small body size. MLH was heritable (h2 = 0.14) and significantly predicted the number of grandoffspring, indicating the potential for genetic benefits based on heterozygosity. We also found support for local heterozygosity effects, which may reflect a noneven distribution of genetic load across the genome. MHC genotype was not significantly associated with any tested fitness component, or with the load of Gyrodactylus parasites. Neither MHC nor MLH was significant predictor of sexually selected traits. Overall, our results highlight the role of heterozygosity in determining fitness, but do not provide support for male sexually selected traits being indicators of genetic quality. [ABSTRACT FROM AUTHOR]

In response to uncertain risks, prey may rely on neophobic phenotypes to reduce the costs associated with the lack of information regarding local conditions. Neophobia has been shown to be driven by information reliability, ambient risk and predator diversity, all of which shape uncertainty of risk. We similarly expect environmental conditions to shape uncertainty by interfering with information availability. In order to test how environmental variables might shape neophobic responses in Trinidadian guppies (Poecilia reticulata), we conducted an in situ field experiment of two high‐predation risk guppy populations designed to determine how the 'average' and 'variance' of several environmental factors might influence the neophobic response to novel predator models and/or novel foraging patches. Our results suggest neophobia is shaped by water velocity, microhabitat complexity, pool width and depth, as well as substrate diversity and heterogeneity. Moreover, we found differential effects of the 'average' and 'variance' environmental variables on food‐ and predator‐related neophobia. Our study highlights that assessment of neophobic drivers should consider predation risk, various microhabitat conditions and neophobia being tested. Neophobic phenotypes are expected to increase the probability of prey survival and reproductive success (i.e. fitness), and are therefore likely linked to population health and species survival. Understanding the drivers and consequences of uncertainty of risk is an increasingly pressing issue, as ecological uncertainty increases with the combined effects of climate change, anthropogenic disturbances and invasive species. [ABSTRACT FROM AUTHOR]

Intraspecific sex differences in morphology, physiology, and behavior are widespread among taxa. However, despite their fundamental importance, they have been relatively understudied in the context of risk assessment. For instance, with Trinidadian guppies (Poecilia reticulata), there has been a bias toward the exclusive use of females, as males are thought to be less responsive to acute predation threats. However, there is little empirical evidence supporting this assumption. Moreover, the antipredator behavior of male guppies has been unexplored, perhaps resulting in the over-generalization of female behavior to both sexes in previous studies. Here, we conducted laboratory experiments involving wild-caught and laboratory-reared guppies. In Experiment 1, shoals of either male or female guppies from a high-predation population were tested for their response to alarm cues, novel odor, or a water control. We found that while female shoals exhibited strong antipredator responses to alarm cues and neophobic responses to novel odor, male shoals exhibited only a weak response to alarm cues and no evidence of neophobia. In Experiment 2, we exposed male and female guppies to high- or low-predation risk and then tested individuals for their responses to alarm cues, novel odor, or water control. Regardless of background risk, males did not respond to any stimulus. In contrast, low-risk females exhibited antipredator responses toward alarm cues and those from high background risk displayed neophobia. Our results suggest that females are more cautious when encountering an acute predation risk, highlighting the importance of accounting for both sexes in studies on predation. [ABSTRACT FROM AUTHOR]

Discovery of two novel tilapia lake virus-like virus isolates in the transcriptomic data of guppy fish (Poecilia reticulata) Keywords: amnoonvirus; guppy fish; tilapia lake virus; TiLV; transcriptomic data reanalysis EN amnoonvirus guppy fish tilapia lake virus TiLV transcriptomic data reanalysis 1015 1019 5 08/11/23 20230901 NES 230901 INTRODUCTION Next-generation sequencing technology has revolutionized the era of modern microbiology by identifying novel viruses without prior knowledge of the nucleotide sequences present in the clinical samples (Bassi et al., [7]). However, given that tilapia populations may be susceptible to these two viruses due to its sequence resemblance to the TiLVs identified so far, further analyses are required to evaluate the clinical relevance of the two TiLV-like viruses and investigate their geographic distribution and virus-host interactions. Since there is currently only one approved virus species within the I Amnoonviridae i , no species demarcation criterion is available now, to the best of the author's knowledge, to determine whether the two isolates are qualified enough to constitute a new virus species or in fact represent a distinct lineage of TiLV based on the sequence identity values and host ranges. [Extracted from the article]