Clade diversification dynamics and the biotic andabiotic controls of speciation and extinction rates

Robin Aguilée, Fanny Gascuel, Amaury Lambert, Regis Ferriere, Nature Communications August 2018

How ecological interactions, genetic processes, and environmental variability jointly shape the evolution of species diversity remains a challenging problem in biology. We developed an individual-based model of clade diversification to predict macroevolutionary dynamics when resource competition, genetic differentiation, and landscape fluctuations interact. Diversification begins with a phase of geographic adaptive radiation. Extinction rates rise sharply at the onset of the next phase. In this phase of niche self-structuring, speciation and extinctionprocesses, albeit driven by biotic mechanisms (competition and hybridization), have essentially constant rates, determined primarily by the abiotic pace of landscape dynamics. The final phase of diversification begins when intense competition prevents dispersing individuals from  establishing  new  populations.  Species’ ranges  shrink,  causing  negative  diversity-dependence of speciation rates. These results show how ecological and microevolutionary processes shape macroevolutionary dynamics and rates; they caution against the notion of ecological limits to diversity, and suggest new directions for the phylogenetic analysis of diversification.

Open access to article licensed under a Creative Commons Attribution 4.0 Internatinal License

Using Small Spatial Units to Refine Our Perception of Rural America

François-Michel Le Tourneau, GeoJournal August 2018 Vol. 82 n° 4 p. 803–817

More than half of the US rural population lives inside metro or micropolitan areas and even at more disaggregated scales, such as the census tracts, most spatial units mix rural and urban population. At a national scale, only 30% of the country are inhabited by 100% urban or 100% rural population, implying that more than two third of the US territory are somewhere in between both situations. As the rural/urban dichotomy appears today to be blurred by the emergence of new phenomena like rurbanization or exurbanization, our perception of rural America may be somewhat twisted and the reality of rural areas underplayed. This paper focuses on using finer-grade spatial units such as the census blocks and block groups, in order to provide new elements about the extension, localization and characteristics of rural America as well as about its inner dynamics. To that end, we analyze and process geographical and social data at these two levels of information, and use population density as a main factor of analysis. This allows us not only to propose new measurement of the extent of rural space in the USA but also to propose a new vision of its spatial dynamics by studying how several social indicators such as income, median age or sex ratio reveal regional and micro-regional variations and situations in the rural part of the US.

The “Common-Pool Resources” Put to the Test of Mining Activity: The Case of the Constancia Project in Peru

Claude Le Gouill, Critique Internationale 2017/4 N° 77

The article draws upon the natural resources management model developed by economist Elinor Ostrom to examine the Constancia (Peru) mining project. It's a study of local communities’ capacity for decentralized and adaptive management within the new rhetoric of sustainable mining advanced by the companies. In what ways does this new mode of regulation allow local communities to provide for their self-organization? Do they have any influence in the very hierarchical power relations characteristic of the mining context? At issue is their ability to maintain sovereignty over their territories and manage the “Common-Pool Resources”. By taking into account the mediating role played by new professionals in the participatory process institutionalized by the state, the Peruvian legal framework offers a relevant example for analyzing the relationships of these communities with the mining companies.

Environmental Conflict and Public Participation in the Semi-arid Southwestern United States: The Rosemont Mining Proposal, Pima County, Arizona

Anne-Lise Boyer, Claude Le Gouill, Franck Poupeau, Lala Razafimahefa, Participations 2017/3 N° 19 p. 189-217

The study focuses on the public participation process that was implemented in the United States by the National Environmental Protection Act. It analyzes the stakeholders’ discourses, which were produced within institutional forums of participation in the case of the Rosemont mine proposal. Our results show that this kind of public participation reaches a socio-economically large and diverse public. However, the public is strongly controlled by interest groups, therefore the participation process can be defined in terms of “quantity” rather than “quality.” This article reveals that analyzing public participation helps to assess environmental controversies.