Declining metabolic scaling parallels an ontogenetic change from elongate to deep-bodied shapes in juvenile Brown trout

Body shape and metabolic rate can be important determinants of animal performance,yet often their effects on influential traits are evaluated in a non-integrated way.This creates an important gap because the integration between shape and metabolism may be crucial to evaluate metabolic scaling theories.Here,we measured standard metabolic rate in 1-and 2-years old juvenile brown trout Salmo trutta,and used a geometric morphometrics approach to extricate the effects of ontogeny and size on the link between shape and metabolic scaling.We evidenced near-isometric ontogenetic scaling of metabolic rate with size,but also a biphasic pattern driven by a significant change in metabolic scaling,from positive to negative allometry.Moreover,the change in metabolic allometry parallels an ontogenetic change from elongate to deep-bodied shapes.This is consistent with the dynamic energy budget(DEB)and surface area(SA)theories,but not with the resource transport network theory which predicts increasing allometric exponents for trends towards more robust,three-dimensional bodies.In addition,we found a relationship between body shape and size independent metabolic rate,with a positive correlation between robustness and metabolic rate,which fits well within the view of Pace-of-Life Syndromes(POLS).Finally,our results align with previous studies that question the universality of metabolic scaling exponents and propose other mechanistic models explaining the diversity of metabolic scaling relationships or emphasizing the potential contribution of ecological factors.

Quantifying the Influence of Websites Based on Online Collective Attention Flow

The availability of network big data, such as those from online users＇ surfing records, communication records, and e-commerce records, makes it possible for us to probe into and quantify the regular patterns of users＇ long-range and complex interactions between websites. If we see the Web as a virtual living organism, according to the metabolic theory, the websites must absorb ＂energy＂ to grow, reproduce, and develop. We are interested in the following two questions： 1） where does the ＂energy＂ come from？ 2） will the websites generate macro influence on the whole Web based on the ＂energy＂？ Our data consist of more than 30 000 online users＇ surfing log data from China Internet Network Information Center. We would consider the influence as metabolism and users＇ attention flow as the energy for the websites. We study how collective attention distributes and flows among different websites by the empirical attention flow network. Different from traditional studies which focused on information flow, we study users＇ attention flow, which is not only a ＂reversed＂ way to study Web structure and transmission mode, but also the first step to understand the underlying dynamics of the World Wide Web. We find that the macro influence of websites scales sub-linearly against the collective attention flow dwelling time, which is not consistent with the heuristics that the more users＇ dwelling time is, the greater influence a website will have. Further analysis finds a supper-linear scaling relationship between the influence of websites and the attention flow intensity. This is a websites version of Kleiber＇s law. We further notice that the development cycle of the websites can be split into three phases： the uncertain growth phase, the partially accelerating growth phase, and the fully accelerating growth phase. We also find that compared with the widespread hyperlinks analysis models, the attention flow network is an effective theoretical tool to estimate and rank websites.

Elevational patterns of carbon,nitrogen and phosphorus in understory bryophytes on the eastern slope of Gongga Mountain,China

Aims The nutrient uptake,requirement and releasing rates of bryophytes are very different from those of tracheophytes.However,it is diffi-cult to make a quantitative evaluation of bryophytes’roles in nu-trient cycling and their specific eco-physiological adaptations due to lack of knowledge of their concentrations and stoichiometric ratios of carbon(C),nitrogen(N)and phosphorus(P).To fill this gap,the present study aims to investigate:(i)what are the elevational trends of C,N and P concentrations and stoichiometric ratios of bryophytes?(ii)whether C,N and P concentrations and stoichio-metric ratios of bryophytes differ between different bryophyte types(in terms of the growth form and living substrate)?and(iii)how do the exponent scalings of N and P of bryophytes change along the elevational gradient?Methods We measured and calculated the C,N,P concentrations and stoi-chiometric ratios of bryophytes from four elevations on the eastern slope of Gongga Mountain(22 species in total).Differences in these traits among elevations,and between different bryophyte types were compared.The log-log allometric regression parameters of N and P at each elevation were also determined and compared.Important Findings The C,N and P concentrations of bryophytes showed decreasing trends with increasing elevations.More specifically,erect bryo-phytes possessed higher C and N concentrations than those of pros-trate species,and terricolous species had higher P concentration than that of corticolous and saxicolous species.Bryophytes from different elevations had an invariant allometric regression slope for P versus N.Future research at a larger scale is in need for a more generalized law of bryophytes.