An individual-based model for simulating the ecological and evolutionary dynamics of drosophila cultures under different scenarios of larval crowding

Abstract

The motivation for this simulation study is the realization in our laboratory over the past several years that experimental populations of Drosophila subjected to larval crowding every generation can actually evolve greater competitive ability via fairly different sets of phenotypes, depending on the ecological details of how exactly the larval crowding was imposed (Sarangi 2013; Nagarajan et al. 2016; Sarangi et al. 2016; M. Sarangi and A. Joshi, unpubl. data). Earlier work on multiple sets of selected and control Drosophila melanogaster populations had suggested that populations subjected to larval crowding evolve greater competitive ability largely through an increased larval feeding rate and greater tolerance to metabolic wastes (Mueller 1997; Joshi et al. 2001; Prasad and Joshi 2003; Mueller and Cabral 2012). The more recent studies, however, indicate that which suite of traits evolves in crowding-adapted Drosophila populations is likely dependent on the total volume of food available in the crowded cultures, and not just the density in terms of egg per unit volume of food (Sarangi 2013; Nagarajan et al. 2016; Sarangi et al. 2016; M. Sarangi and A. Joshi, unpubl. data). In this context, it will be important to be able to examine the effects of different ecological scenarios of larval crowding implemented through differing protocols in selection experiments using Drosophila. Due to logistical constraints, large numbers of selection experiments cannot be carried out. Therefore, computer simulations that enable a systematic examination of the evolutionary dynamics of different suites of fitness-related phenotypes in Drosophila populations subjected to larval crowding in different ways can be very useful in narrowing down the list of possible selection experiments to identify those that will offer the greatest understanding for the effort put in.