Coevolution can stabilize a mutualistic interaction

Interspecific mutualisms are ubiquitous in nature, despite their ecological and evolutionary instability. Recent studies have developed coevolutionary theory of mutualisms, which coupled population and evolutionary dynamics, to resolve the longstanding puzzle. However, earlier studies assumed a time-scale separation between these dynamics, leaving an unanswered question of how a relaxation in the time-scale separation affects the coevolutionary dynamics of mutualism. Here I relax the strong assumption to theoretically show that ecological and evolutionary dynamics occurring in a similar time scale can stabilize an otherwise unstable mutualism. I show that the coevolutionary dynamics can cause a stable limit cycle or stable equilibrium in the population sizes, even if the population sizes increase unbounded in the absence of evolutionary adaptation. In contrast, coevolution can also cause stable limit cycle even if the population dynamics is stable in the absence of evolutionary adaptation. Furthermore, the model predicts that the population dynamics is likely to converge to equilibrium when the evolutionary speed of two species is similar and fast or highly dissimilar. The results suggest that the ease of the evolutionary ‘arms race’ is of crucial importance to maintain mutualism.     

Toward a Marxian anthropology? Bare,abstract, mobile,global

Anthropology has conventionally taken as some of its most cherished foundational categories the precise opposites of the key concepts that animate this inquiry: rather than “bare life,” anthropology has tended always to emphasize the fullness and complexity of social and political life; instead of labor in the abstract, which we recognize in its commodified form as “labor-power,” anthropology has produced exquisite inventories of concrete laboring activities and the “cultural” content of productive work; against the impermanence and mutability of lives characterized by their mobility, the ethnographic enterprise has been deeply attached to the sedentarist presuppositions of lasting settlement, dwelling, and “community”; and contrary to the task of apprehending space on a global scale, ethnographic study has been overwhelmingly localized and place-bound. Rethinking these elementary premises of the ethnographic endeavor and situating these critical concepts at the center of our epistemological frameworks are crucial theoretical and practical tasks for any meaningful social inquiry today. In this regard, the Marxian theoretical arsenal is simply indispensable. But, in the derisive words of so many disciplinary forebears and overseers, is this properly “anthropological”? The prospective convergence of genuinely critical sociopolitical inquiry with the techniques and insights of anthropology must remain for us the locus of an urgent problem—an open question on an open horizon.