Interaction rates,vital rates,background fitness and replicator dynamics: how to embed evolutionary game structure into realistic population dynamics

In this paper we are concerned with how aggregated outcomes of individual behaviours, during interactions with other individuals (games) or with environmental factors, determine the vital rates constituting the growth rate of the population. This approach needs additional elements, namely the rates of event occurrence (interaction rates). Interaction rates describe the distribution of the interaction events in time, which seriously affects the population dynamics, as is shown in this paper. This leads to the model of a population of individuals playing different games, where focal game affected by the considered trait can be extracted from the general model, and the impact on the dynamics of other events (which is not neutral) can be described by an average background fertility and mortality. This leads to a distinction between two types of background fitness, strategically neutral elements of the focal games (correlated with the focal game events) and the aggregated outcomes of other interactions (independent of the focal game). The new approach is useful for clarification of the biological meaning of concepts such as weak selection. Results are illustrated by a Hawk–Dove example.     

Design and synthesis of multisubstrate analog inhibitors of one-carbon transfer reactions

The design and synthesis of multisubstrate analog enzyme inhibitors offer new opportunities in the creation of potent, highly specific drug molecules. Selected examples of inhibitors of 1-carbon transfer serve to illustrate the potential of this approach. Inhibitors of indole-N-methyltransferase, L-aspartyl transcarbamoylase, and thymidylate synthase are illustrative of many compounds that have demonstrated considerable specificity and potency. Several of these inhibitors and the rationale for their syntheses are described.     

A method for assessing sustainability,with beef production as an example

A comprehensive approach to decisions about the use of land and other world resources, taking full account of biological and other scientific information, is crucial for good decisions to be made now and in future. The sustainability of systems for producing food and other products is sometimes assessed using too narrow a range of component factors. A production system might be unsustainable because of adverse effects on a wide range of aspects of human welfare, animal welfare, or the environment. All factors should be included in sustainability evaluation, otherwise products or actions might be avoided without adequate consideration of key factors or of the diversity of production systems. A scoring method that is based on scientific information and potentially of general relevance is presented here, using beef production as a example with a review of each of its sustainability components. This includes an overall combined score and specific factors that make the system unacceptable for some consumers. The results show that, in this example, the sustainability of the best systems is very much better than that of the worst systems. By taking account of scores for a wide range of components of sustainability in comparing beef-production systems, better quality policies about beef use can be formulated than when statements referring only to one system are considered. The least sustainable beef-production systems are extensive grazing that causes land degradation and the use of feedlots or indoor housing with grain feeding. Semi-intensive silvopastoral systems are the most sustainable beef-production systems, and well-managed pasture-fed beef from areas where crop production is uneconomic is also sustainable. This simple, scientifically based scoring system could be modified to use positive as well as negative scores and is of value for policy makers, researchers, producers, organisations aiming to improve sustainability, and the general public.     

Small-scale field mapping of lichen distribution in three dimensions with a computer-based position-tracking system

A trial was undertaken with an electromagnetic position-tracking (Tracker) system by mapping a small section of a lichen habitat near Cape Royds, Ross Island, Antarctica. This method facilitated the simultaneous collection of precise information about both the topography of the site and the distribution of lichen species. These data were used to produce accurate maps and three-dimensional reconstructions of the mapped area. The technique offers considerable savings in time over conventional methods used in plant and lichen surveys, and has potential to enhance the information collected from broader-scale transect surveys. Received: 6 January 1999 / Accepted: 23 January 1999     

The stochastic modelling of kleptoparasitism using a Markov process

Kleptoparasitism, the stealing of food items from other animals, is a common behaviour observed across a huge variety of species, and has been subjected to significant modelling effort. Most such modelling has been deterministic, effectively assuming an infinite population, although recently some important stochastic models have been developed. In particular the model of Yates and Broom (Stochastic models of kleptoparasitism. J. Theor. Biol. 248 (2007), 480-489) introduced a stochastic version following the original model of Ruxton and Moody (The ideal free distribution with kleptoparasitism. J. Theor. Biol. 186 (1997), 449-458), and whilst they generated results of interest, they did not solve the model explicitly. In this paper, building on methods used already by van der Meer and Smallegange (A stochastic version of the Beddington-DeAngelis functional response: Modelling interference for a finite number of predators. J. Animal Ecol. 78 (2009) 134-142) we give an exact solution to the distribution of the population over the states for the Yates and Broom model and investigate the effects of some key biological parameters, especially for small populations where stochastic models can be expected to differ most from their deterministic equivalents.     

You can run--or you can hide: optimal strategies for cryptic prey against pursuit predators

We consider the optimal behavior of a cryptic prey individualas it is approached by a predator searching for prey. Althoughthe predator has not yet discovered the prey, it has an increasinglikelihood of doing so as it gets closer to the prey. Further,the closer the predator is to the prey when it discovers it,the more likely the predator will be to capture the prey. Thesearguments suggest that the prey should flee before the predatordiscovers it. However, the act of fleeing will alert the predatorto the presence of the prey and trigger an attack that mightnot have occurred otherwise. We capture these conflicting outcomesin a mathematical model, which we then use to predict the optimalbehavior of the prey and predator. We argue that the optimalstrategy for the prey is either to run as soon as they detecta predator approaching or to only flee in response to havingbeen detected by the predator. Running as soon as the predatoris detected is associated with low predator search speeds, alow nonpredation cost to running, a large advantage to the preyin initiating chases rather than reacting, limited ability tospot the predator at distance, a high ability to spot prey bythe predator, and a high probability that chases will be successful.The optimal strategy for the predator depends on whether itscurrent trajectory is taking it closer to or further from theprey. In the latter case, the predator should attack immediatelyon discovering the prey; in the former case, it should delayits attack until it reaches the point on its current trajectorywhere distance to the prey is minimized.