Evolution of sociality by natural selection on variances in reproductive fitness: evidence from a social bee

<p>Abstract</p> <p>Background</p> <p>The Central Limit Theorem (CLT) is a statistical principle that states that as the number of repeated samples from any population increase, the variance among sample means will decrease and means will become more normally distributed. It has been conjectured that the CLT has the potential to provide benefits for group living in some animals via greater predictability in food acquisition, if the number of foraging bouts increases with group size. The potential existence of benefits for group living derived from a purely statistical principle is highly intriguing and it has implications for the origins of sociality.</p> <p>Results</p> <p>Here we show that in a social allodapine bee the relationship between cumulative food acquisition (measured as total brood weight) and colony size accords with the CLT. We show that deviations from expected food income decrease with group size, and that brood weights become more normally distributed both over time and with increasing colony size, as predicted by the CLT. Larger colonies are better able to match egg production to expected food intake, and better able to avoid costs associated with producing more brood than can be reared while reducing the risk of under-exploiting the food resources that may be available.</p> <p>Conclusion</p> <p>These benefits to group living derive from a purely statistical principle, rather than from ecological, ergonomic or genetic factors, and could apply to a wide variety of species. This in turn suggests that the CLT may provide benefits at the early evolutionary stages of sociality and that evolution of group size could result from selection on variances in reproductive fitness. In addition, they may help explain why sociality has evolved in some groups and not others.</p

Density, Viscosity, Solubility, and Diffusivity of N2O in Aqueous Amino Acid Salt Solutions

Solubility and diffusivity of N2O in aqueous solutions of potassium taurate are reported over a wide range of concentration and temperature. Also, the solubility of N2O in aqueous potassium glycinate solution is reported at 295 K. The ion specific constants are reported for taurate and glycinate anions. A modified Stokes-Einstein relationship is proposed for the diffusivity of N2O in aqueous potassium taurate solution in the temperature range 293-308 K.

Gas solubility of H2S and CO2 in aqueous solutions of N-methyldiethanolamine

Alkanolamine processes are used in the industry to remove acid gases, like CO2, H2S and other sulphur components, from natural gas and industrial gas streams. In this process the acid components react with the basic alkanolamine solution via an exothermic, reversible reaction in a gas/liquid absorber. The composition of these amine solutions is continuously changed to optimise the (selective) removal of the several acid components. For the design of gas treating equipment accurate mass transfer, reaction kinetics and solubility data of acid gases in aqueous alkanolamine solutions are required. In this paper new solubility data of H2S and CO2 in aqueous MDEA at different conditions encountered in modern gas treating facilities are presented. The experimental pressure and temperature were varied from 6.9 to 69 bar (methane was used as make-up gas) and from 10 to 25 °C respectively. These new solubility data were evaluated and correlated with an Electrolyte Equation of State Model (EOS) as originally proposed by Fürst and Renon [Fürst, W., Renon, H., 1993. Representation of Excess Properties of Electrolyte Solutions Using a New Equation of State. AIChE J., 39 (2), pp. 335.]. The application of Equation of State Models for the prediction of VLE data for reactive, ionic systems is a rather new development in this field.

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Criminal Justice: Legitimacy, accountability, and effectivit

Women in healthcare in Imperial Russia: the contribution of the surgeon Nikolay I. Pirogov

Nikolay Ivanovich Pirogov, one of the greatest Russian surgeons of the 19th Century, was convinced of the importance of deploying nurses to care for the casualties of war. With the support of Grand Duchess Elena Pavlovna, sister-in-law of Tsar Nikolas I, Pirogov realised the idea during the Crimean war when Russia became the first country to send female nurses to the battle front. Later in the 19th century, large numbers of Russian women trained as nurses under the auspices of the Russian Red Cross, founded in 1867. In peacetime, their expertise was extremely valuable.</p