Community involvement in management for maintaining coral reef resilience and biodiversity in southern Caribbean marine protected areas

Climate change is posing new challenges to conservation because management policies on protected coral reefs are less effective than they were before the current ecosystem degradation. Coral reefs, the most diverse and complex marine ecosystem provide economic services for millions, but are seriously threatened worldwide because reef-building corals are experiencing bleaching phenomena and a steady decline in abundance. The resources of a Marine Protected Area (MPA) in Cartagena, Colombia, are in constant decline, despite a current management plan and on-site staff, urging new conservation actions. A multidisciplinary team gathered to evaluate management effectiveness including biophysical, socioeconomic and governance indicators. Coral cover and fish diversity and abundance were low both inside and outside the MPA, which suggests a limited efficiency of management. Currently, the MPA is a reef with low coral cover and high algae cover as well as large dead coral areas, which are generally signs of highly degraded reef habitats. Live coral cover in the MPA was represented by pioneer coral species such as Agaricia tenuifolia and Porites astreoides. Nonetheless, 35% of the scleractinian species sampled in the area harbored more than one zooxanthellae symbiont, which suggests potential resistance and resilience against coral bleaching. Maintenance of trophic structure and functional diversity is an important endeavor that should be a priority for management in order to allow ecosystem resilience. Social and governance indicators showed low-income levels and few opportunities for communities living in and around the park, low governability, weak communication among stakeholders and with authorities at different levels. As a result, problems related to over exploitation of resources were commonplace in the MPA. These results reflect low adaptive capacity of communities to comply with restrictive conservation rules, showing that establishment of a protected area is a necessary but insufficient condition to guarantee conservation goals. Ignoring the role of local communities only will exacerbate the problems associated with natural resources. Involvement of communities in strategic ecosystems management appears to be a requisite to improve effectiveness of protected areas, and participatory strategies, such as co-management, offer opportunities to improve governability while letting communities adapt to MPA needs.     

Effect of food deprivation on dominance status in blue-footed booby (Sula nebouxii) broods

A pecking hierarchy is normally established in the usual two-chickbrood of the blue-footed booby (Sula nebouxii). The senior (first-hatched)chick dominates its smaller sibling and receives a greater shareof parentally provided food. Experimental broods were createdby putting together two unrelated junior chicks of die sameage in a vacated foster nest The state of the chicks was manipulatedby a period of controlled artificial feeding so that each chickunderwent a different level of food deprivation. The resultingdominance relationship depended on the relative food deprivationlevel of the chicks: the hungrier chick normally became dominant.However, die effect of hunger was occasionally overruled bysize difference: when die hungrier chick was much smaller thanits foster sibling, it was unable to gain dominance over itslarger companion. Dominance status is likely to have greatervalue for die hungrier chick, while die cost of fighting shouldbe lower for die larger chick. These results conform to dieevolutionarily stable strategy predicted for games widi asymmetricpayoff and differences in resource holding power.     

Spatial invasion of cooperation

The evolutionary puzzle of cooperation describes situations where cooperators provide a fitness benefit to other individuals at some cost to themselves. Under Darwinian selection, the evolution of cooperation is a conundrum, whereas non-cooperation (or defection) is not. In the absence of supporting mechanisms, cooperators perform poorly and decrease in abundance. Evolutionary game theory provides a powerful mathematical framework to address the problem of cooperation using the prisoner's dilemma. One well-studied possibility to maintain cooperation is to consider structured populations, where each individual interacts only with a limited subset of the population. This enables cooperators to form clusters such that they are more likely to interact with other cooperators instead of being exploited by defectors. Here we present a detailed analysis of how a few cooperators invade and expand in a world of defectors. If the invasion succeeds, the expansion process takes place in two stages: first, cooperators and defectors quickly establish a local equilibrium and then they uniformly expand in space. The second stage provides good estimates for the global equilibrium frequencies of cooperators and defectors. Under hospitable conditions, cooperators typically form a single, ever growing cluster interspersed with specks of defectors, whereas under more hostile conditions, cooperators form isolated, compact clusters that minimize exploitation by defectors. We provide the first quantitative assessment of the way cooperators arrange in space during invasion and find that the macroscopic properties and the emerging spatial patterns reveal information about the characteristics of the underlying microscopic interactions.     

Is there a role for amplifiers in sexual selection?

The amplifier hypothesis states that selection could favour the evolution of traits in signallers that improve the ability of receivers to extract honest information from other signals or cues. We provide a formal definition of amplifiers based on the receiver's mechanisms of signal perception and we present a game-theoretical model in which males advertise their quality and females use sequential-sampling tactics to choose among prospective mates. The main effect of an amplifier on the female mating strategy is to increase her mating threshold, making the female more selective as the effectiveness of the amplifier increases. The effects of the amplifier on male advertising strategy depends both on the context and on the types of the amplifier involved. We consider two different contexts for the evolution of amplifiers (when the effect of amplifiers is on signals and when it is on cues) and two types of amplifiers (the ‘neutral amplifier’, when it improves quality assessment without altering male attractiveness, and the ‘attractive amplifier’, when it improves both quality assessment and male attractiveness). The game-theoretical model provides two main results. First, neutral and attractive amplifiers represent, respectively, a conditional and an unconditional signalling strategy. In fact, at the equilibrium, neutral amplifiers are displayed only by males whose advertising level lays above the female acceptance threshold, whereas attractive amplifiers are displayed by all signalling males, independent of their quality. Second, amplifiers of signals increase the differences in advertising levels between amplifying and not-amplifying males, but they decrease the differences within each group, so that the system converges towards an ‘all-or-nothing’ signalling strategy. By applying concepts from information theory, we show that the increase in information transfer at the perception level due to the amplifier of signals is contrasted by a decrease in information transfer at the emitter level due to the increased stereotypy of male advertising strategy.     

A stochastic model of evolutionary dynamics with deterministic large-population asymptotics

An evolutionary birth-death process is proposed as a model of evolutionary dynamics. Agents residing in a continuous spatial environment X, play a game G, with a continuous strategy set S, against other agents in the environment. The agents’ positions and strategies continuously change in response to other agents and to random effects. Agents spawn asexually at rates that depend on their current fitness, and agents die at rates that depend on their local population density. Agents’ individual evolutionary trajectories in X and S are governed by a system of stochastic ODEs. When the number of agents is large and distributed in a smooth density on (X,S), the collective dynamics of the entire population is governed by a certain (deterministic) PDE, which we call a fitness-diffusion equation.     

A platform for evolving intelligently interactive adversaries

Entertainment software developers face significant challenges in designing games with broad appeal. One of the challenges concerns creating nonplayer (computer-controlled) characters that can adapt their behavior in light of the current and prospective situation, possibly emulating human behaviors. This adaptation should be inherently novel, unrepeatable, yet within the bounds of realism. Evolutionary algorithms provide a suitable method for generating such behaviors. This paper provides background on the entertainment software industry, and details a prior and current effort to create a platform for evolving nonplayer characters with genetic and behavioral traits within a World War I combat flight simulator.     

Natural selection and veridical perceptions

Does natural selection favor veridical perceptions, those that more accurately depict the objective environment? Students of perception often claim that it does. But this claim, though influential, has not been adequately tested. Here we formalize the claim and a few alternatives. To test them, we introduce “interface games,” a class of evolutionary games in which perceptual strategies compete. We explore, in closed-form solutions and Monte Carlo simulations, some simpler games that assume frequency-dependent selection and complete mixing in infinite populations. We find that veridical perceptions can be driven to extinction by non-veridical strategies that are tuned to utility rather than objective reality. This suggests that natural selection need not favor veridical perceptions, and that the effects of selection on sensory perception deserve further study.     

Electronic Games and Environmental Factors Associated with Childhood Obesity in Switzerland

Objective: Environmental factors and behaviors associated with obesity have not been well described in children living in Europe. Although television watching has been repeatedly associated with obesity, it is unclear whether other sedentary activities, such as use of electronic games, are independently associated with obesity in children. The hypothesis was that various types of sedentary activities are associated with obesity in children living in Switzerland. Research Methods and Procedures: This was a cross‐sectional study of children (grades one to three) from four communities in the Greater Zurich Area (Switzerland). Obesity was defined as a combination of overweight (BMI) and overfat (skinfold thicknesses). Environmental factors were assessed by questionnaire. The children's physical activity was estimated by their teacher (scale 0 to 10). Results: Of 922 eligible subjects, 872 (94.6%) took part in the study. Use of electronic games [odds ratio (OR) = 2.03 per hour per day, 95% confidence interval (CI): 1.57 to 2.61, p < 0.001], television (OR = 2.83 per hour per day, 95% CI: 2.08 to 3.86, p < 0.001), physical activity (OR = 0.80 per unit, 95% CI: 0.72 to 0.88, p < 0.001), maternal work (OR = 1.93, 95% CI: 1.13 to 3.29, p = 0.02), and paternal smoking (OR = 1.78, 95% CI: 1.07 to 2.96, p = 0.03) were independently associated with obesity. Further adjustment for socioeconomic status, when available, did not change these results. Discussion: In this sample of children living in Switzerland, the use of electronic games was significantly associated with obesity, independently of confounding factors. The association of obesity with television use and lack of physical activity confirms results from other populations and points to potential strategies for obesity prevention.     

A game theoretical approach to the evolution of structured communication codes

Structured meaning-signal mappings, i.e., mappings that preserve neighborhood relationships by associating similar signals with similar meanings, are advantageous in an environment where signals are corrupted by noise and sub-optimal meaning inferences are rewarded as well. The evolution of these mappings, however, cannot be explained within a traditional language evolutionary game scenario in which individuals meet randomly because the evolutionary dynamics is trapped in local maxima that do not reflect the structure of the meaning and signal spaces. Here we use a simple game theoretical model to show analytically that when individuals adopting the same communication code meet more frequently than individuals using different codes—a result of the spatial organization of the population—then advantageous linguistic innovations can spread and take over the population. In addition, we report results of simulations in which an individual can communicate only with its K nearest neighbors and show that the probability that the lineage of a mutant that uses a more efficient communication code becomes fixed decreases exponentially with increasing K. These findings support the mother tongue hypothesis that human language evolved as a communication system used among kin, especially between mothers and offspring.     

Wild Carib grackles play a producer scrounger game

Producer–scrounger (PS) game-theoretical foraging modelsmake predictions about the decision of group-feeding animalseither to look for food (produce) or for opportunities to exploitthe discoveries of other foragers (scrounge). We report themost complete demonstration to date of the applicability ofthe PS foraging game in a free-living animal, the Carib grackle(Quiscalus lugubris) of Barbados. As assumed by PS games, thepayoffs obtained by scroungers were negatively frequency dependent.Experimentally, increasing the cost of scrounging led to a decreasein the observed proportion of scroungers, whereas raising thecost of producing increased the proportion of scroungers. Observationsof marked birds revealed that group-level changes could be broughtabout by individual flexibility in tactic use. Despite consistentindividual differences in tactic use, most birds used both tacticsand could alter their use of producing and scrounging when conditionschanged. We found no difference in the payoffs obtained by producersand scroungers, suggesting a symmetrical game equilibrium. Ourresults call for testing the PS foraging game in a broader rangeof biological systems that include different types of scroungingbehavior (e.g., scramble, stealthful, or aggressive scrounging)as well as the exploitation of different phases of food production(e.g., searching, handling).