The Durability of Public Goods Changes the Dynamics and Nature of Social Dilemmas

An implicit assumption underpins basic models of the evolution of cooperation, mutualism and altruism: The benefits (or pay-offs) of cooperation and defection are defined by the current frequency or distribution of cooperators. In social dilemmas involving durable public goods (group resources that can persist in the environment–ubiquitous from microbes to humans) this assumption is violated. Here, we examine the consequences of relaxing this assumption, allowing pay-offs to depend on both current and past numbers of cooperators. We explicitly trace the dynamic of a public good created by cooperators, and define pay-offs in terms of the current public good. By raising the importance of cooperative history in determining the current fate of cooperators, durable public goods cause novel dynamics (e.g., transient increases in cooperation in Prisoner's Dilemmas, oscillations in Snowdrift Games, or shifts in invasion thresholds in Stag-hunt Games), while changes in durability can transform one game into another, by moving invasion thresholds for cooperation or conditions for coexistence with defectors. This enlarged view challenges our understanding of social cheats. For instance, groups of cooperators can do worse than groups of defectors, if they inherit fewer public goods, while a rise in defectors no longer entails a loss of social benefits, at least not in the present moment (as highlighted by concerns over environmental lags). Wherever durable public goods have yet to reach a steady state (for instance due to external perturbations), the history of cooperation will define the ongoing dynamics of cooperators

Herpetological observations from field expeditions to North Karnataka and Southwest Maharashtra, India

The Western Ghats of India are one of the 34 global hotspots of biodiversity. They are one of the most important large natural areas in the world and are fast becoming recognised for their biological importance. The herpetofauna of the Western Ghats is hugely diverse, with many species exhibiting rare, endemic styles of autecology and niche preference that could equal that of countries such as Borneo and Madagascar. In this report we detail 18 amphibian and 37 reptile species from eight sites following three expeditions to the Western Ghats from 2007-2009. The report details species descriptions, habitat, ecology and conservation to alert the herpetological community to the importance of future research to address the lack of knowledge in species ecology. It also presents newinformation on species distribution and behaviour

Multilocus Bayesian Estimates of Intra-Oceanic Genetic Differentiation, Connectivity, and Admixture in Atlantic Swordfish (Xiphias gladius L.)

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Some environmental factors influencing phytoplankton in the Southern Ocean around South Georgia

Data on phytoplankton and zooplankton biomass, and physical and chemical variables, are combined with a published multivariate description of diatom species composition to interpret variation within an area around South Georgia surveyed during an austral summer. Large-scale species distributions could be equated to the different water masses which reflected the interaction of the Antarctic Circumpolar Current with the island and the Scotia Ridge. Small-scale factors were found to act at an interstation scale and imposed local variation on the biogeographic pattern. Nutrient depletion could be related to phytoplankton biomass but no single inorganic nutrient of those measured (NO 3 −N, PO 4 −P and silica) could be identified as important. The ratio Si:P appeared to be more important as an ecological factor. The impact of grazing by krill and other zooplankton could only be resolved as differences in phytoplankton biomass and phaeopigment content. Diatom species composition showed a relation to local krill abundance very different from that suggested by published studies, but could be explained as the effect of earlier grazing outside the study area. The effects of vertical mixing could not account for interstation differences as pycnocline depth was uniformly greater than euphotic depth, and vertical stability very low. Some comparison was made with data collected in 1926–31 by the Discovery Investigations. Significant differences in the distribution of certain taxa such as Chaetoceros criophilum and C. socialis were traced to major differences in hydrology.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46983/1/300_2004_Article_BF00443379.pd

Measuring plot scale woodland structure using terrestrial laser scanning

Terrestrial laser scanning (TLS) can be used to characterize a woodland site by measuring structural attributes of the vegetation community. In Australia, government funded programs monitor vegetation structure using manual field surveys to assess change and ecological condition. In this study, we examined whether structural attributes commonly assessed in woodland ecology surveys can be extracted from a single TLS scan. Attributes of the ground, shrub and overstory vegetation layers were evaluated at nine open woodland sites in central Western Queensland. We used 0.1\ua0m voxels to aggregate returns. Our results show that, compared with field assessment by highly experienced ecologists, TLS can rapidly characterize structural attributes for tree canopy cover, maximum tree height, average tree height (R\ua0>\ua00.9) and average diameter at breast height (R\ua0=\ua00.77). However, we could not accurately determine shrub height, shrub canopy cover, shrub average height, ground cover (grass, litter and coarse woody debris) or the number of trees per hectare (R\ua