Dusky groupers (Epinephelus marginatus) are characterized by a complex sex allocation strategies and overexploitation of bigger individuals. We developed an individual based model to investigate the long-term effects of density dependence on grouper population dynamics and to analyze the variabilities of extinction probabilities as a result of interacting mortalities at different life stages. We conduct several simulations with different forms of sex allocation functions and different combinations of mortality rates. The model was parametrized using data on dusky grouper populations from (...) the literature. The most important insights produced by this simulation study are that density dependence of sex allocation is an evolutionarily stable strategy, increases the population biomass, mitigates the effect of the removal of large male and indicates a need for protection of females and flexible stages. (shrink)

Dusky groupers ( Epinephelus marginatus ) are characterized by a complex sex allocation strategies and overexploitation of bigger individuals. We developed an individual based model to investigate the long-term effects of density dependence on grouper population dynamics and to analyze the variabilities of extinction probabilities as a result of interacting mortalities at different life stages. We conduct several simulations with different forms of sex allocation functions and different combinations of mortality rates. The model was parametrized using data on dusky grouper (...) populations from the literature. The most important insights produced by this simulation study are that density dependence of sex allocation is an evolutionarily stable strategy, increases the population biomass, mitigates the effect of the removal of large male and indicates a need for protection of females and flexible stages. (shrink)

COVID-19 has crowned1 a number of other disasters (wildfires in Australia, Desert Locusts in Kenya, an imminent WWIII merging Iran and the US), causing panic to click into place and horror to become our global predicament, making us realize that we live in the illusion of the permanence of things, of mastery, and of immortality. People’s turning to social media for trans-local news on COVID-19 has stirred great ire in the world. This led to the proliferation of dark images that (...) associate the viral catastrophe with the end as we know it. To problematize the idea of the apocalypse (or the end) this paper speaks of three moments of survival in human existence: the beneath, the behind and the beyond. We argue that the apocalyptic nature of the pandemic and its global horrorism are part of a congeries of apocalyptic simulations that have always been part of the narrative with which we try to define ourexistence on earth. This paper masks itself against perfunctory examinations of the term apocalypse, and offers instead an understanding that runs along the lines of its Greek etymological sense as apokalyptein (revelation). It offers what Foucault calls an ontology of the present, that interrogates the history of COVID -19 with an emphasis neither on its origin nor on its telos. As beyondists, the COVID-19 catastrophe has revealed to us that 1) we have ‘access to knowledge beyond knowledge’ (see Gumpert Citation2012), and therefore that 2) our modern predicament is not very modern. The end, (not) to be sure, has been lived and relived in the boundary between reality and simulation. After all, the end of something comprises the beginning (in reverse) of that which “endeth”, throwing the beyond, behind and beneath in the Ferris wheel of epistemological and existential entanglement. (shrink)

We consider a two-patch epidemiological system where individuals can move from one patch to another, and local interactions between the individuals within a patch are governed by the classical SIRS model. When the time-scale associated with migration is much smaller than the time-scale associated with infection, aggregation methods can be used to simplify the initial complete model formulated as a system of ordinary differential equations. Analysis of the aggregated model then shows that the two-patch basic reproduction rate is smaller than (...) the 1 patch one. We extend this result to a linear chain of P patches . These results are illustrated by some examples for which numerical integration of the system of ordinary differential equations is performed. Simulations of an individual based model implemented with a multi-agent system are also carried out. (shrink)