Social tagging, guppy effect and the role of interference : a quantum-inspired model for tags combination

Social tagging systems are shown to evidence a well known cognitive heuristic, the guppy effect, which arises from the combination of different concepts. We present some empirical evidence of this effect, drawn from a popular social tagging Web service. The guppy effect is then described using a quantum inspired formalism that has been already successfully applied to model conjunction fallacy and probability judgement errors. Key to the formalism is the concept of interference, which is able to capture and quantify the strength of the guppy effect.

Studies on fecundity, sex ratio and crossbreeding in different strains of Guppy

Studies on the fecundity, sex ratio and crossbreeding in different strains of the guppy Poecilia reticulata such as Butterfly I, Butterfly II and Cobra strains was carried out. The highest fecundity among Butterfly I strain was at the 5th breed while it was highest at the 6th and 8th breed among Butterfly II and Cobra strain respectively. The average male percentage was 39.88%, 43.39% and 45.02% among Butterfly I, Butterfly II and Cobra strains respectively. The crossbreeding of strains showed good results among crossbreeds of Butterfly II (♀) X Cobra (♂) and Butterfly I (♀) X Cobra (♂). The crossbreed among the Butterfly I (♀) X Cobra (♂) proved to be excellent from the point of view of more percentage, rapid growth, and brilliant body and finnage colouration.

In vitro culture of embryonic hearts from guppy fish (Poecilia reticulata)

Forty embryonic hearts were taken out by anatomical needle from denuded embryos of the ovoviviparity guppy fish that were dechorioned by mechanic method or by trypsin digestion, and were in vitro cultured. In the cultured hearts, 80% have maintained beating in vitro for 4 weeks, and the longest record for beating was 142 d. Owing to fish embryo transparency, beating frequency and blood color changes are easily viewed from the embryonic hearts under a dissecting microscope. The current study established the in vitro culture method of embryonic hearts in guppy fish, which can be used as a model for the study of heart and cardiovascular system in vertebrates.

Length-weight relationship and reproduction of the guppy Poecilia reticulata (Cyprinodontiformes: Poeciliidae) in urban drainage channels in the Brazilian city of Belém

O presente trabalho tem por objetivo descrever aspectos populacionais relacionados ao estabelecimento da relação peso/comprimento, estimativa de tamanho de primeira maturação (L) e período reprodutivo de Poecilia reticulata encontrados em sistemas de coleta residual no campus da Universidade Federal do Pará, região metropolitana de Belém – PA (Brasil). Foram realizadas coletas mensais no período de junho de 2006 a março de 2007, utilizando um puçá, que resultou na captura de 1.936 exemplares, sendo 942 machos e 994 fêmeas. As fêmeas apresentaram-se maiores e mais pesadas que os machos. A relação peso/comprimento para machos foi estabelecida pela equação Pt = 5 × 10^-5× Ct^2,397 e para fêmeas esta foi dada pela fórmula Pt = 3 × 10^-6 × Ct3,419. Os valores estimados para L foi 17,5 mm para machos 20,4 mm para fêmeas, sugerindo que os machos iniciam atividades reprodutivas em tamanhos menores que as fêmeas. A frequência mensal de fêmeas maduras não variou significativamente. Além disso, também não foram encontradas diferenças na proporção sexual durante os períodos investigados, sendo no geral, a proporção de fêmeas iguais as de machos. Desta forma, verificamos que, apesar das condições presentes nos sistemas de coleta residual da UFPA, a espécie P. reticulata parece ter adaptado seus processos biológicos.

Female mating preference for bold males in the guppy, Poecilia reticulata.

Although females prefer to mate with brightly colored males in numerous species, the benefits accruing to such females are virtually unknown. According to one hypothesis of sexual selection theory, if the expression of costly preferred traits in males (such as conspicuous colors) is proportional to the male's overall quality or reveals his quality, a well-developed trait should indicate good condition and/or viability for example. A female choosing such a male would therefore stand to gain direct or indirect fitness benefits, or both. Among potential phenotypic indicators of an individual's quality are the amount and brightness of its carotenoid-based colors and its boldness, as measured by its willingness to risk approaching predators without being killed. Here, we show experimentally that in the Trinidadian guppy (Poecilia reticulata) the visual conspicuousness of the color pattern of males correlates positively with boldness toward, and with escape distance from, a cichlid fish predator. Bold individuals are thus more informed about nearby predators and more likely to survive encounters with them. Mate-choice experiments showed that females prefer colorful males as mates, but prefer bolder males irrespective of their coloration when given the opportunity to observe their behavior toward a potential fish predator. By preferentially mating with colorful males, female guppies are thus choosing on average, relatively bold, and perhaps more viable, individuals. In doing so, and to the extent that viability is heritable, they potentially gain indirect fitness benefits by producing more viable offspring than otherwise.

Does 2-wheeler experience affect behaviours and attitudes to 2-wheelers as a car driver?

• Car-bicycle and car-motorcycle crashes often serious • Car driver mostly at fault, often because of failure to see (Schramm et al, 2010) • Car drivers with motorcycling experience less likely to be involved in motorcycle crashes or be at fault (Brooks & Guppy, 1990; Magazzu et al., 2006) and hold more positive beliefs about motorcyclists (Crundall et al., 2008) • Does bicycle riding experience have the same benefits?

Use of phosphorus fertiliser for increased productivity of legume-based sown pastures in the Brigalow Belt region – a review

The Brigalow Belt bioregion of southern and central Queensland supports a large percentage of northern Australia's sown pastures and beef herd. The Brigalow soils were widely thought to have adequate phosphorus (P) for cropping, sown pastures and grazing animals, which has led to almost no use of P fertiliser on sown pastures. The majority of pastures established in the region were sown with tropical grasses only (i.e. no legumes were sown). Under grass-only pastures, nitrogen (N) mineralisation rates decline with time since establishment as N is 'tied-up' in soil organic matter. This process leads to a significant decline in pasture and animal productivity and is commonly called 'pasture rundown'. Incorporating pasture legumes has been identified as the best long-term solution to improve the productivity of rundown sown grass pastures. Pasture legumes require adequate P to grow well and fix large amounts of N to increase the productivity of rundown sown grass pastures. Producers and farm advisors have traditionally thought that P fertiliser is not cost-effective for legume-based improved pastures growing on inland areas of Queensland despite there being little, if any, data on production responses or their economic outcomes. Recent studies show large and increasing areas of low plant available soil P and large responses by pasture legumes to P fertiliser on Brigalow soils. The economic analysis in this scoping study indicates potential returns of 9–15% on extra funds invested from the application of P fertiliser, when establishing legumes into grass pastures on low P soils (i.e. lower than the critical P requirement of the legume grown). Higher returns of 12–24% may be possible when adding P fertiliser to already established grass/legume pastures on such soils. As these results suggest potential for significant returns from applying P fertiliser on legume pastures, it is recommended that research be conducted to better quantify the impacts of P fertiliser on productivity and profit. Research priorities include: quantifying the animal production and economic impact of fertilising legume-based pastures in the sub-tropics for currently used legumes; quantifying the comparative P requirements and responses of available legume varieties; understanding clay soil responses to applied P fertiliser; testing the P status of herds grazing in the Brigalow Belt; and quantifying the extent of other nutrient deficiencies (e.g. sulphur and potassium) for legume based pastures. Development and extension activities are required to demonstrate the commercial impacts of applying P fertiliser to legume based pastures.

Influence of size, station time and satiation amount on prey handling time in Anabas testudineus (Bloch)

Satiation amount, satiation time and handling time of Anabas testudineus (Bloch), an air breathing predatory fish was experimentally estimated using guppy (Lebistes reticulatus) as prey. Weight of the fish and satiation time influenced prey handling time. As satiation time is related to the level of hunger, level of hunger was found to influence handling time of prey.

Development of a rapid, sensitive and specific diagnostic assay for fish Aquareovirus based on RT-PCR

A rapid, sensitive and highly specific detection method for Aquareovirus based on reverse-transcription polymerase chain reaction (RT-PCR) was developed. Based on multiple sequence alignment of the cloned sequences of a local isolates, the Threadfin reovirus (TFV) and Guppy reovirus (GPV) with Grass carp reovirus (GCRV), a pair of degenerate primers was selected carefully and synthesized. Using this primer combination, only one specific product, approximately 450 bp in length was obtained when RT-PCR was carried out using the genomic double-stranded RNA (dsRNA) of TFV, GPV and GCRV. Similar results were also obtained when Chum salmon reovirus (CSRV) and Striped bass reovirus (SBRV) dsRNA were used as templates. No products were observed when nucleic acids other than the dsRNA of the aquareoviruses described above were used as RT-PCR templates. This technique could detect not only TFV but also GPV and GCRV in low titer virus-infected cell cultured cells. Furthermore, this method has also been shown to be able to diagnose GPV-infected guppy (Poecilia reticulata) that exhibit clinical symptoms as well as GPV-carrier guppy. Collectively, these results showed that the RT-PCR amplification method using specific degenerate primers described below is very useful for rapid and accurate detection of a variety of aquareovirus strains isolated from different host species and origin. (C) 2004 Elsevier B.V. All rights reserved.

Experimental evaluation of evolution and coevolution as agents of ecosystem change in Trinidadian streams.

Evolution has been shown to be a critical determinant of ecological processes in some systems, but its importance relative to traditional ecological effects is not well known. In addition, almost nothing is known about the role of coevolution in shaping ecosystem function. Here, we experimentally evaluated the relative effects of species invasion (a traditional ecological effect), evolution and coevolution on ecosystem processes in Trinidadian streams. We manipulated the presence and population-of-origin of two common fish species, the guppy (Poecilia reticulata) and the killifish (Rivulus hartii). We measured epilithic algal biomass and accrual, aquatic invertebrate biomass, and detrital decomposition. Our results show that, for some ecosystem responses, the effects of evolution and coevolution were larger than the effects of species invasion. Guppy evolution in response to alternative predation regimes significantly influenced algal biomass and accrual rates. Guppies from a high-predation site caused an increase in algae relative to guppies from a low-predation site; algae effects were probably shaped by observed divergence in rates of nutrient excretion and algae consumption. Rivulus-guppy coevolution significantly influenced the biomass of aquatic invertebrates. Locally coevolved populations reduced invertebrate biomass relative to non-coevolved populations. These results challenge the general assumption that intraspecific diversity is a less critical determinant of ecosystem function than is interspecific diversity. Given existing evidence for contemporary evolution in these fish species, our findings suggest considerable potential for eco-evolutionary feedbacks to operate as populations adapt to natural or anthropogenic perturbations.

Eco-evolutionary trophic dynamics: loss of top predators drives trophic evolution and ecology of prey.

Ecosystems are being altered on a global scale by the extirpation of top predators. The ecological effects of predator removal have been investigated widely; however, predator removal can also change natural selection acting on prey, resulting in contemporary evolution. Here we tested the role of predator removal on the contemporary evolution of trophic traits in prey. We utilized a historical introduction experiment where Trinidadian guppies (Poecilia reticulata) were relocated from a site with predatory fishes to a site lacking predators. To assess the trophic consequences of predator release, we linked individual morphology (cranial, jaw, and body) to foraging performance. Our results show that predator release caused an increase in guppy density and a "sharpening" of guppy trophic traits, which enhanced food consumption rates. Predator release appears to have shifted natural selection away from predator escape ability and towards resource acquisition ability. Related diet and mesocosm studies suggest that this shift enhances the impact of guppies on lower trophic levels in a fashion nuanced by the omnivorous feeding ecology of the species. We conclude that extirpation of top predators may commonly select for enhanced feeding performance in prey, with important cascading consequences for communities and ecosystems.

Eco-evolutionary feedbacks in community and ecosystem ecology: interactions between the ecological theatre and the evolutionary play.

Interactions between natural selection and environmental change are well recognized and sit at the core of ecology and evolutionary biology. Reciprocal interactions between ecology and evolution, eco-evolutionary feedbacks, are less well studied, even though they may be critical for understanding the evolution of biological diversity, the structure of communities and the function of ecosystems. Eco-evolutionary feedbacks require that populations alter their environment (niche construction) and that those changes in the environment feed back to influence the subsequent evolution of the population. There is strong evidence that organisms influence their environment through predation, nutrient excretion and habitat modification, and that populations evolve in response to changes in their environment at time-scales congruent with ecological change (contemporary evolution). Here, we outline how the niche construction and contemporary evolution interact to alter the direction of evolution and the structure and function of communities and ecosystems. We then present five empirical systems that highlight important characteristics of eco-evolutionary feedbacks: rotifer-algae chemostats; alewife-zooplankton interactions in lakes; guppy life-history evolution and nutrient cycling in streams; avian seed predators and plants; and tree leaf chemistry and soil processes. The alewife-zooplankton system provides the most complete evidence for eco-evolutionary feedbacks, but other systems highlight the potential for eco-evolutionary feedbacks in a wide variety of natural systems.

Habitat simplification increases the impact of a freshwater invasive fish

Biodiversity continues to decline at a range of spatial scales and there is an urgent requirement to understand how multiple drivers interact in causing such declines. Further, we require methodologies that can facilitate predictions of the effects of such drivers in the future. Habitat degradation and biological invasions are two of the most important threats to biodiversity and here we investigate their combined effects, both in terms of understanding and predicting impacts on native species. The predatory largemouth bass Micropterus salmoides is one of the World’s Worst Invaders, causing declines in native prey species, and its introduction often coincides with habitat simplification. We investigated the predatory functional response, as a measure of ecological impact, of juvenile largemouth bass in artificial vegetation over a range of habitat complexities (high, intermediate, low and zero). Prey, the female guppy Poecilia reticulata, were representative of native fish. As habitats became less complex, significantly more prey were consumed, since, even although attack rates declined, reduced handling times resulted in higher maximum feeding rates by bass. At all levels of habitat complexity, bass exhibited potentially population destabilising Type II functional responses, with no emergence of more stabilising Type III functional responses as often occurs in predator-prey relationships in complex habitats. Thus, habitat degradation and simplification potentially exacerbate the impact of this invasive species, but even highly complex habitats may ultimately not protect native species. The utilisation of functional responses under varying environmental contexts provides a method for the understanding and prediction of invasive species impacts.