53 research outputs found
Community-based management induces rapid recovery of a high-value tropical freshwater fishery
Tropical wetlands are highly threatened socio-ecological systems, where local communities rely heavily on aquatic animal protein, such as fish, to meet food security. Here, we quantify how a ‘win-win’ community-based resource management program induced stock recovery of the world’s largest scaled freshwater fish (Arapaima gigas), providing both food and income. We analyzed stock assessment data over eight years and examined the effects of protected areas, community-based management, and landscape and limnological variables across 83 oxbow lakes monitored along a ~500-km section of the Juruá River of Western Brazilian Amazonia. Patterns of community management explained 71.8% of the variation in arapaima population sizes. Annual population counts showed that protected lakes on average contained 304.8 (±332.5) arapaimas, compared to only 9.2 (±9.8) in open-access lakes. Protected lakes have become analogous to a high-interest savings account, ensuring an average annual revenue of US1046.6 per household, greatly improving socioeconomic welfare. Arapaima management is a superb window of opportunity in harmonizing the co-delivery of sustainable resource management and poverty alleviation. We show that arapaima management deserves greater attention from policy makers across Amazonian countries, and highlight the need to include local stakeholders in conservation planning of Amazonian floodplains
Cooperation, Norms, and Revolutions: A Unified Game-Theoretical Approach
Cooperation is of utmost importance to society as a whole, but is often
challenged by individual self-interests. While game theory has studied this
problem extensively, there is little work on interactions within and across
groups with different preferences or beliefs. Yet, people from different social
or cultural backgrounds often meet and interact. This can yield conflict, since
behavior that is considered cooperative by one population might be perceived as
non-cooperative from the viewpoint of another.
To understand the dynamics and outcome of the competitive interactions within
and between groups, we study game-dynamical replicator equations for multiple
populations with incompatible interests and different power (be this due to
different population sizes, material resources, social capital, or other
factors). These equations allow us to address various important questions: For
example, can cooperation in the prisoner's dilemma be promoted, when two
interacting groups have different preferences? Under what conditions can costly
punishment, or other mechanisms, foster the evolution of norms? When does
cooperation fail, leading to antagonistic behavior, conflict, or even
revolutions? And what incentives are needed to reach peaceful agreements
between groups with conflicting interests?
Our detailed quantitative analysis reveals a large variety of interesting
results, which are relevant for society, law and economics, and have
implications for the evolution of language and culture as well
Differential Expressions of Adhesive Molecules and Proteases Define Mechanisms of Ovarian Tumor Cell Matrix Penetration/Invasion
Epithelial ovarian cancer is an aggressive and deadly disease and understanding its invasion mechanisms is critical for its treatment. We sought to study the penetration/invasion of ovarian tumor cells into extracellular matrices (ECMs) using a fibroblast-derived three-dimensional (3D) culture model and time-lapse and confocal imaging. Twelve ovarian tumor cells were evaluated and classified into distinct groups based on their ECM remodeling phenotypes; those that degraded the ECM (represented by OVCAR5 cells) and those that did not (represented by OVCAR10 cells). Cells exhibiting a distinct ECM modifying behavior were also segregated by epithelial- or mesenchymal-like phenotypes and uPA or MMP-2/MMP-9 expression. The cells, which presented epithelial-like phenotypes, penetrated the ECM using proteases and maintained intact cell-cell interactions, while cells exhibiting mesenchymal phenotypes modified the matrices via Rho-associated serine/threonine kinase (ROCK) in the absence of apparent cell-cell interactions. Overall, this study demonstrates that different mechanisms of modifying matrices by ovarian tumor cells may reflect heterogeneity among tumors and emphasize the need to systematically assess these mechanisms to better design effective therapies
Expanding the Paradigms of Plant Pathogen Life History and Evolution of Parasitic Fitness beyond Agricultural Boundaries
International audienc
Long-Term Seasonal and Interannual Patterns of Marine Mammal Strandings in Subtropical Western South Atlantic
Understanding temporal patterns of marine mammal occurrence is useful for establishing
conservation strategies. We used a 38 yr-long dataset spanning 1976 to 2013 to describe
temporal patterns and trends in marine mammal strandings along a subtropical stretch of
the east coast of South America. This region is influenced by a transitional zone between
tropical and temperate waters and is considered an important fishing ground off Brazil. Generalized
Additive Models were used to evaluate the temporal stranding patterns of the most
frequently stranded species. Forty species were documented in 12,540 stranding events.
Franciscana (n = 4,574), South American fur seal, (n = 3,419), South American sea lion (n =
2,049), bottlenose dolphins (n = 293) and subantarctic fur seal (n = 219) were the most frequently
stranded marine mammals. The seasonality of strandings of franciscana and bottlenose
dolphin coincided with periods of higher fishing effort and strandings of South
American and subantarctic fur seals with post-reproductive dispersal. For South American
sea lion the seasonality of strandings is associated with both fishing effort and post-reproductive
dispersal. Some clear seasonal patterns were associated with occurrence of cold-
(e.g. subantarctic fur seal) and warm-water (e.g. rough-toothed dolphin) species in winter
and summer, respectively. Inter-annual increases in stranding rate were observed for franciscana
and South American fur seal and these are likely related to increased fishing effort
and population growth, respectively. For subantarctic fur seal the stranding rate showed a
slight decline while for bottlenose dolphin it remained steady. No significant year to year variation
in stranding rate was observed for South American sea lion. The slight decrease in
frequency of temperate/polar marine mammals and the increased occurrence of subtropical/tropical
species since the late 1990s might be associated with environmental changes
linked to climate change. This long-term study indicates that temporal stranding patterns of
marine mammals might be explained by either fishing-related or environmental factors
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