Costly induction of defense reduces plant growth and alters reproductive traits in mixed-mating Datura stramonium

Herbivory shapes plant trait evolution by altering allocation to growth and defense in ways that affect plant reproduction and fitness. Initiation of these trade-offs may be particularly strong in juvenile plants with high phenotypic plasticity. Herbivory costs are often measured in terms of plant size or flower numbers, but other herbivore-induced floral changes can alter interactions with pollinators and have important implications for mating systems. In mixed-mating plants that can both self-fertilize and outcross, herbivory can maintain mating system variation if herbivore damage and defensive induction change a plant’s likelihood of selfing versus outcrossing. Here, I use mixed-mating Datura stramonium to evaluate how early defensive induction and herbivory result in trade-offs among plant defense, growth and reproduction. I used a 2×2 factorial manipulation of early chemical defense induction and season-long insecticide in the field. Growth costs of chemical induction were seen even before plants received damage, indicating an inherent cost of defense. Induction and herbivory changed multiple aspects of floral biology associated with a plant’s selfing or outcrossing rate. This including reduced floral allocation, earlier flowering, and reduced anther-stigma separation (herkogamy). Although these floral changes are associated with decreased attractiveness to pollinators, plants exposed to natural herbivory did not have decreased seed set. This is likely because their floral morphologies became more conducive to selfing (via reduced herkogamy). These vegetative and floral changes following damage and defensive induction can impact interactions among plants (by altering mating environment) and interactions with pollinators (via changes in floral allocation and floral phenology).

Peace with the Planet

This chapter traces the coalescence between pacifist and environmental concerns around the issue of nuclear weapons testing in the 1950s and early 1960s in the West. Scientists, health professionals, educators, and middle-class families grew increasingly concerned about the health hazards of fallout from nuclear testing. They built a grassroots movement that transcended the traditional Cold War divisions and ignored political warnings about the need for nuclear deterrence against the communist threat. Clean soil, clean air, and clean food, as well as the health of current and future generations of children, were at stake, making the cost of defense against an abstract communist enemy too high a price to pay for many. The struggle for peace thus expanded from political-ideological to the medical-environmental realm.

Population and Evolutionary Dynamics based on Predator–Prey Relationships in a 3D Physical Simulation

Recent studies have reported that population dynamics and evolutionary dynamics, occurring at different time scales, can be affected by each other. Our purpose is to explore the interaction between population and evolutionary dynamics using an artificial life approach based on a 3D physically simulated environment in the context of predator–prey and morphology–behavior coevolution. The morphologies and behaviors of virtual prey creatures are evolved using a genetic algorithm based on the predation interactions between predators and prey. Both population sizes are also changed, depending on the fitness. We observe two types of cyclic behaviors, corresponding to short-term and long-term dynamics. The former can be interpreted as a simple population dynamics of Lotka–Volterra type. It is shown that the latter cycle is based on the interaction between the changes in the prey strategy against predators and the long-term change in both population sizes, resulting partly from a tradeoff between their defensive success and the cost of defense.

Auditing procurement contracts for defense material in Spain: In the footsteps of the U.S. model

In Spain contract auditing has been applied since 1988 to determine the final cost of defense procurement contracts. In this respect, the Spanish Department of Defense takes the US methodology as a reference model, and therefore it may be useful to study the degree of convergence between the two models. The main objective of this paper is to analyze the degree to which the US contract auditing model for the procurement of defense materiel has influenced the system applied in Spain. Accordingly, the comparative method is used to highlight the main features of the contract auditing models used by the Spanish and the US Departments of Defense. The results obtained show that the methodology used by Spain is not an original approach, but that there is only a low degree of convergence with the US model.

Costs and benefits of Daphnia defense against Chaoborus in nature

To estimate costs and benefits of antipredator defenses in the Chaoborus–Daphnia system, we employed lake enclosures wherein controls (C) had no predators, the predation (P) treatment had freely swimming Chaoborus, and the kairomone (K) treatment predators were sequestered in a mesh tube apart from the Daphnia. Population growth (r) of two Daphnia pulex clones, one responsive (RC) and the other nonresponsive (NRC) to Chaoborus kairomone, was estimated for each predator treatment. Cost of defense was calculated as r(C,RC) – r(K,RC). Benefit was calculated as r(P,RC) – r(P,NRC). Antipredator defenses of Daphnia towards Chaoborus kairomone led to a 32% reduction in population growth in nature. The benefit of the defense, however, was a short-term 68% enhanced population growth by a responsive over a nonresponsive clone in the presence of the actual predation threat. The benefit of the defense exceeded the cost, but cost was nevertheless substantial. Our results verify that the in situ effects of Chaoborus on Daphnia involve direct and indirect impacts.