Posts Tagged ‘Exponent’

Academy of Social Sciences Names 83 New Fellows

The Academy of Social Sciences has conferred the award of fellow on 83 leading social scientists, including such luminaries as Lord Stern, Nudge Unit founder David Halpern and Madeleine Atkins of HEFCE.

The post Academy of Social Sciences Names 83 New Fellows appeared first on Social Science Space.

Metabolic allometric scaling model. Combining cellular transportation and heat dissipation constraints [RESEARCH ARTICLE]

Yuri K. ShestopaloffLiving organisms need energy to be “alive”. Energy is produced by biochemical processing of nutrients. The rate of energy production is called metabolic rate. Metabolism is very important from evolutionary, ecological perspectives, …

Take-off speed in jumping mantises depends on body size and a power limited mechanism [RESEARCH ARTICLE]

G.P. Sutton, M. Doroshenko, D.A. Cullen, and M. BurrowsMany insects such as fleas, froghoppers and grasshoppers use a catapult mechanism to jump and a direct consequence of this is that their take-off velocities are independent of their mass. In contr…

Pawar et al. reply

replying to H. C. Giacomini, B. Shuter, D. T. de Kerckhove & P. A. Abrams Nature 493, (2012)
Current studies assume that per-capita consumption rates always scale with body mass to an exponent of 0.75. We showed that, contrary to this assumption, consumption rates scale sublinearly (exponent of approximately 0.85) when organisms forage in two dimensions (2D), and superlinearly (exponent of approximately 1.06) when they forage in 3D. Giacomini et al. argue that the superlinear scaling in 3D interactions we observed cannot be reconciled with life-history theory for maximal body size. Consequently, they search for biases in our study that might cause this superlinear scaling. However, their comments do not challenge our central result that consumption rates scale superlinearly in 3D, and significantly more steeply than in 2D. We propose instead that life-history theory may need revision to include interaction dimensionality.

Dimensionality of consumer search space drives trophic interaction strengths

Trophic interactions govern biomass fluxes in ecosystems, and stability in food webs. Knowledge of how trophic interaction strengths are affected by differences among habitats is crucial for understanding variation in ecological systems. Here we show how substantial variation in consumption-rate data, and hence trophic interaction strengths, arises because consumers tend to encounter resources more frequently in three dimensions (3D) (for example, arboreal and pelagic zones) than two dimensions (2D) (for example, terrestrial and benthic zones). By combining new theory with extensive data (376 species, with body masses ranging from 5.24 × 10−14 kg to 800 kg), we find that consumption rates scale sublinearly with consumer body mass (exponent of approximately 0.85) for 2D interactions, but superlinearly (exponent of approximately 1.06) for 3D interactions. These results contradict the currently widespread assumption of a single exponent (of approximately 0.75) in consumer–resource and food-web research. Further analysis of 2,929 consumer–resource interactions shows that dimensionality of consumer search space is probably a major driver of species coexistence, and the stability and abundance of populations.

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