Theoretical and empirical investigations on population stability and dispersal evolution using laboratory populations of drosophila melanogaster

Abstract

Global climate is changing rapidly and is accompanied by large scale fragmentation and destruction of habitats These environmental adversities not only affecting the life history and behaviour of organisms but also compromise the stability of local population dynamics Although a number of control methods for stabilizing the dynamics had been proposed there were no comparisons of the relative efficiencies of these methods More critically majority of these methods had not yet been validated empirically Therefore I undertook theoretical study that compared six such control methods in terms of attaining a given level of stability over four different life history environment combinations This analysis showed that although no single method was unambiguously superior to others the methods that involved culling reduce the risk of extinction more efficiently whereas methods that involve only restocking are better in reducing temporal fluctuations in population sizes Subsequently using a series of experiments I validated the efficiency of four well known control methods in enhancing the stability of widely fluctuating extinction prone populations of Drosophila melanogaster These experiment showed that methods which incorporate both culling and restocking can simultaneously achieve multiple kinds of stability and therefore are strong candidates for field applications I also showed that the choice of methods under a given condition would depend critically upon what kind of stability needs to be attained Non Drosophila specific biologically realistic simulations suggested the generalizability of these results over a wide range of taxa Subsequently in order to obtain mechanistic insights about the determinants of dynamics and stability I built an individual based stage structured model of Drosophila dynamics This model included parameters that are common to the life history of several holometabolus insects I calibrated this model using data from laboratory populations of Drosophila melanogaster The calibrated mo