John Maynard Smith and the importance of consistency in evolutionary game theory

John Maynard Smith was the founder of evolutionary game theory. He has also been the major influence on the direction of this field, which now pervades behavioural ecology and evolutionary biology. In its original formulation the theory had three components: a set of strategies, a payoff structure, and a concept of evolutionary stability. These three key components are still the basis of the theory, but what is assumed about each component is often different to the original assumptions. We review modern approaches to these components. We emphasis that if a game is considered in isolation, and arbitrary payoffs are assumed, then the payoffs may not be consistent with other components of the system which are not modelled. Modelling the whole system, including not only the focal game, but also the future behaviour of the players and the behaviour of other population members, allows a consistent model to be constructed. We illustrate this in the case of two models of parental care, showing how linking a focal game to other aspects of the system alters what is predicted.     

Specific sensing between inositol epimers by a bis(boronate)

Bis(boronates) that utilize internal photoinduced electron transfer (PET) quenching mechanisms can specifically signal the binding of chiro-inositol without responding to its epimer, myo-inositol.     

Synaptic protein UNC-13 interacts with an F-box protein that may target it for degradation by proteasomes

UNC-13 protein participates in regulating neurotransmitter release. In Drosophila melanogaster, proteasomal degradation controls UNC-13 levels at synapses. Function of the amino-terminal region of a 207 kDa form of Caenorhabditis elegans UNC-13 is unknown. Yeast two-hybrid and secondary yeast assays identified an F-box protein that interacts with this amino-terminal region. As F-box proteins bind proteins targeted for proteasomal degradation, this protein may participate in degrading a subset of UNC-13 proteins, suggesting that different forms of UNC-13 are regulated differently. Yeast assays also identified an exonuclease, a predicted splicing factor, and a protein with coiled-coil domains, indicating that UNC-13 may affect RNA function.     

The cholecystokinin type A receptor g.179A>G polymorphism affects feeding rate

A polymorphism within the 5' untranslated region of the cholecystokinin type A receptor ( CCKAR ) gene has been shown to affect feed intake and growth in commercial pig lines. To further investigate the phenotype of animals carrying alternative alleles at this polymorphism, we genotyped animals from a distinct segregating commercial line and an experimental cross F₂ population, both with electronically recorded feeding pattern data. The data indicate that the daily feed intake increasing effect of the DQ496228:g.179G allele is mediated through a faster rate of feed intake, without evidence for an effect on other feeding behaviour traits.     

The behavioural ecology of personality: consistent individual differences from an adaptive perspective

Individual humans, and members of diverse other species, show consistent differences in aggressiveness, shyness, sociability and activity. Such intraspecific differences in behaviour have been widely assumed to be non‐adaptive variation surrounding (possibly) adaptive population‐average behaviour. Nevertheless, in keeping with recent calls to apply Darwinian reasoning to ever‐finer scales of biological variation, we sketch the fundamentals of an adaptive theory of consistent individual differences in behaviour. Our thesis is based on the notion that such ‘personality differences’ can be selected for if fitness payoffs are dependent on both the frequencies with which competing strategies are played and an individual's behavioural history. To this end, we review existing models that illustrate this and propose a game theoretic approach to analyzing personality differences that is both dynamic and state‐dependent. Our motivation is to provide insights into the evolution and maintenance of an apparently common animal trait: personality, which has far reaching ecological and evolutionary implications.     

The effect of thermoregulatory substitution on optimal energy reserves of small birds in winter

Previous models have predicted the body mass of small birds in winter on the basis of a trade-off between starvation and predation. Many of these models have assumed that energy expenditure while active increases with body mass. The implications of the fact that the metabolic cost of activity can substitute for internal heat production and help keep the bird warm have not been investigated. In this paper we show that if thermoregulatory substitution occurs then there is a critical level of energy reserves above which an active bird is thermoneutral. This critical level increases as temperature decreases. Below this level, substitution of energy results in higher optimal levels of reserves than would be predicted in the absence of substitution. Our model thus predicts that at low temperatures body mass will be higher when thermoregulatory substitution occurs.     

Sperm allocation strategies and female resistance: a unifying perspective

The classical viewpoint in sperm competition theory, which holds that males evolve sperm allocation strategies in response to a given degree of sperm competition, has recently been challenged by an alternative viewpoint, which holds that the degree of sperm competition is itself a consequence of these same strategies. Here, we present a game theory model that unites these alternative views as the endpoints of a continuum. Based on the recognition that female control over mating may limit the extent to which male strategies affect the degree of sperm competition, we investigate sperm allocation strategies in a setting where females can resist excessive matings more or less successfully. We discuss how conflicting predictions made by previous theory relate to implicit assumptions about female resistance behavior. Moreover, we show that female resistance, while being highly relevant to the predicted relationship between ejaculate size and the degree of sperm competition, has little effect on the predicted positive correlation between relative testis size and the degree of sperm competition. This result strengthens one of the central predictions of sperm competition theory and is in accordance with empirical findings from a wide range of taxa.     

The antihyperglycemic effect of estrone sulfate in genetically obese-diabetic (ob/ob) mice is associated with reduced hepatic glucose-6-phosphatase.

Excessive glucose production by the liver contributes significantly to diabetic hyperglycemia. The enzyme system glucose-6-phosphatase plays a key role in regulating hepatic glucose production and therefore its inhibition is a potential therapeutic target for the correction of hyperglycemia. It has previously been shown that sulfated steroids, such as estrone sulfate and dehydroepiandrosterone sulfate, inhibit the glucose-6-phosphatase system in vitro, principally through inhibition of endoplasmic reticulum glucose-6-phosphate transport. We report here that in the obese/diabetic ob/ob mouse model, orally administered estrone sulfate reduces the abnormally elevated hepatic glucose-6-phosphatase enzyme activity and enzyme protein levels that are characteristic in the ob/ob mouse, and that this reduction is associated with normalization of blood glucose levels. Other sulfated and non-sulfated steroids also reduced, to a lesser extent, glucose-6-phosphatase enzyme activity - with the exception of dehydroepiandrosterone sulfate, which had no apparent effect on this system in ob/ob mice. Estrone sulfate is therefore an effective antihyperglycemic agent in ob/ob mice, and the glucose-6-phosphatase system can be successfully targeted for the therapeutic management of hyperglycemia in this animal model of non-insulin-dependent diabetes mellitus.     

Studies on thermophilic cellulolytic fungi

Three thermophilic cellulolytic fungi, Chaetomium thermophile var. coprophile, Sporotrichum thermophile, and Thermoascus aurantiacus were studied to determine the conditions for a high rate of cellulose degradation. The range of temperature over which good growth occurred was determined first in a temperature gradient incubator; the optimum temperature was then established in shake flask cultures. T. aurantiacus had the highest optimum growth temperature range (46 to 51 C), whereas S. thermophile had the broadest range over which good growth occurred (36 to 43 C). Optimum temperatures for the three organisms, T. aurantiacus, S. Thermophile, and C. thermophile were 48, 40, and 40 C, respectively. It was found that the addition of an organic carbon and nitrogen source to a cellulose mineral solution medium markedly increased the rate of cellulose degradation. The surfactant, Tween 80, which has been reported to be of value in the production and recovery of the enzyme, cellulase, was shown to be detrimental to the degradation of cellulose in culture. In the medium used, S. thermophile gave the highest rate of substrate utilization; 56% of the cellulose was hydrolyzed in 72 h. The average degree of polymerization of cellulose decreased from 745 to 575.