6 research outputs found

    Data: Ecological niche conservatism spurs diversification in response to climate change

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    The dataset contains the configuration and data used to perform the simulations and generate the figures for the paper titled "Ecological niche conservatism spurs diversification in response to climate change", which is going to be online on Nature Ecology & Evolution soon.AbstractA longstanding debate has focused on the relationship between evolutionary innovation in ecological niches of species and rates of biological diversification of those species. As such questions across broad scales of time and space, short-term experiments or scattered fossil evidences are not feasible, and contrasting opinions have emerged: niche innovation might allow species to explore and colonize new geographic areas across which they could speciate, or niche conservatism might augment isolation of populations that could then undergo allopatric speciation. Here, we used an in silico, “virtual world” simulation approach to address these questions. First, we created biological worlds on global scale in which different types of niche evolution could and could not occur, and then examined the resulting virtual species assemblages in terms of levels and patterns of diversity. The outcome was clear: niche conservatism promotes biological diversification, whereas labile niches—whether adapting to conditions available or changing randomly—led to slower diversification rates. This outcome, in the context of burgeoning theoretical and empirical evidence for niche conservatism, provides a framework for understanding how Earth-life interactions produced such a diverse biota.</p

    Levels of Salivary Enzymes of <i>Apolygus Lucorum</i> (Hemiptera: Miridae), From 1<sup>st</sup> Instar Nymph to Adult, and Their Potential Relation to Bug Feeding

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    <div><p>In recent years, <i>Apolygus lucorum</i> has caused increasing damage to cotton and fruit trees in China. The salivary enzymes secreted by <i>A</i>. <i>lucorum</i> when sucking on host plants induce a series of biochemical reactions in plants, and the pre-oral digestion benefits the bug feeding. In this study, the food intake of <i>A</i>. <i>lucorum</i> from 1<sup>st</sup> instar nymphs to adults was measured, and the corresponding salivary activity of pectinase, amylase, cellulase, protease, polyphenol oxidase and peroxidase was determined. Daily food intake varied with developmental stage, peaking in 3<sup>rd</sup> and 4<sup>th</sup> instar nymphs. Pectinase, amylase, cellulase and protease were detected in both nymphal and adult saliva of <i>A</i>. <i>lucorum</i>, while neither polyphenol oxidase nor peroxidase was detected. Protease activity varied with food intake peaking at the 3<sup>rd</sup>-4<sup>th</sup> instar, and then slightly decreasing at the 5<sup>th</sup> instar. Levels of pectinase, amylase and cellulase increased significantly with the daily feeding level until the 3<sup>rd</sup> instar, corresponding with increasing damage to host plants. The activity of both cellulase and protease had a significant linear relationship with the average daily food intake. The increasing activity of enzymes in saliva explain stage-specific impacts of <i>A</i>. <i>lucorum</i> on the host plants, and suggest that optimal management of <i>A</i>. <i>lucorum</i> would be confined to its control threshold prior to the peak of daily feeding in the 3<sup>rd</sup> instar.</p></div

    Adapted finite difference schemes advection-reaction-diffusion problems generating periodic wavefronts

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    The talk is focused on the numerical integration of advection-reaction-diffusion problems by finite difference schemes adapted to problem. In other terms, the numerical scheme, exploiting the a-priori knowledge of the qualitative behaviour of the solution, gains ad- vantages in terms of efficiency and accuracy with respect to classic schemes already known in literature. The adaptation is here carried out through the so-called trigonometrical fitting technique for the discretization in space, giving rise to a system of ODEs whose vector field contains both stiff and non-stiff terms. Due to this mixed nature of the vector field, an Implicit-Explicit (IMEX) method is here employed for the integration in time, based on the first order forward-backward Euler method. The coefficients of the method introduced rely on unknown parameters which have to be properly estimated: such an estimate is performed by minimizing the leading term of the local truncation error in an efficient way. The effectiveness of this problem-oriented approach is shown through a rigorous theoretical analysis and some numerical experiments. References [1] R. D’Ambrosio, M. Moccaldi and B. Paternoster, Adapted numerical schemes for advection-reaction-diffusion problems generating periodic wavefronts, Comp. Math. Appl. (2017). [2] A.J. Perumpanani, J.A. Sherratt, P.K. Maini, Phase differences in reac- tion–diffusion–advection systems and applications to morphogenesis, J. Appl. Math. 55, 19-33 (1995)
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