A model of the evolution of larval feeding rate in Drosophila driven by conflicting energy demands

Abstract

Energy allocation is believed to drive trade-offs in life history evolution. We develop a physiological and genetic model of energy allocation that drives evolution of feeding rate in a well-studied model system. In a variety of stressful environments Drosophila larvae adapt by altering their rate of feeding. Drosophila larvae adapted to high levels of ammonia, urea, and the presence of parasitoids evolve lower feeding rates. Larvae adapted to crowded conditions evolve higher feeding rates. Feeding rates should affect gross food intake, metabolic rates, and efficiency of food utilization. We develop a model of larval net energy intake as a function of feeding rates. We show that when there are toxic compounds in the larval food that require energy for detoxification, larvae can maximize their energy intake by slowing their feeding rates. While the reduction in feeding rates may increase development time and decrease competitive ability, we show that genotypes with lower feeding rates can be favored by natural selection if they have a sufficiently elevated viability in the toxic environment. This work shows how a simple phenotype, larval feeding rates, may be of central importance in adaptation to a wide variety of stressful environments via its role in energy allocation.

Atrazine exposure affects longevity, development time and body size in Drosophila melanogaster

“…This could be mediated be through an alteration in food intake since Drosophila larvae will alter their food intake in response to a variety of toxins in their environment. (Mueller and Barter, 2015; Perkhulyn et al, 2015; Weiner et al, 2014). It is also possible that the gut microbiota is being affected (Broderick and Lemaitre, 2012; Han et al, 2014).…”

Evolution of increased larval competitive ability inDrosophila melanogasterwithout increased larval feeding rate

“…At the same time, since feeding is restricted to a 1 cm deep band, effective competition for access to food, especially in early stages of a crowded culture, will be higher in vials with a greater absolute number of larvae (as in the CU populations), because the volume of food in the 1 cm deep feeding band is constant, but the number of larvae feeding in that zone is higher in the CU cultures compared to the MCU, D. ananassae and D. n. nasuta crowded cultures. As it has been shown theoretically that optimal feeding rates are likely to decline as the concentration of nitrogenous waste in the food increases (Mueller et al 2005;Mueller and Barter 2015), it is likely that the optimal feeding rates in the 1.5 mL crowded cultures are lower than if there is 5-6 mL food per vial. Additionally, since food runs out very fast over time in crowded vials with only 1.5 mL of food, it might not permit better survival of individuals with a high waste tolerance, unlike the case in crowded vials with 5-6 mL of food.…”

“…It is, therefore, possible that the time course of food depletion and nitrogenous waste build-up in the D. ananassae and D. n. nasuta crowded cultures is different from that in the K-and 10 CU populations. It has been shown theoretically that optimal feeding rates are likely to decline as the concentration of nitrogenous waste in the food increases (Mueller et al 2005;Mueller and Barter 2015). Thus, at least in principle, it is possible that the optimal feeding rates in the D. ananassae and D. n. nasuta crowded populations were actually less than they were for the K-and CU populations, and that is why increased feeding rates did not evolve in the former (Nagarajan et al 2014).…”

AyurvedicAmalaki Rasayanapromotes improved stress tolerance and thus has anti-aging effects inDrosophila melanogaster

“…In this study we have examined if rearing of wild type flies on AR supplemented food affects their tolerance to applied stressors like crowding, severe hyperthermia and increased reactive oxygen species (ROS) production. Growth under crowded conditions limits the resources due to decreased availability of food and consequent increases metabolic waste levels which have detrimental effects on survival of the organism (Borash and Ho, 2001;Mueller and Barter, 2015). Crowding stress resulting from rearing of Drosophila larvae at high density causes smaller adult size, reduced fecundity and life span, besides causing increased larval and pupal mortality (Borash and Ho, 2001;Chippindale et al 1993;Mueller and Barter, 2015).…”

“…Growth under crowded conditions limits the resources due to decreased availability of food and consequent increases metabolic waste levels which have detrimental effects on survival of the organism (Borash and Ho, 2001;Mueller and Barter, 2015). Crowding stress resulting from rearing of Drosophila larvae at high density causes smaller adult size, reduced fecundity and life span, besides causing increased larval and pupal mortality (Borash and Ho, 2001;Chippindale et al 1993;Mueller and Barter, 2015). Thermal stress affects many important cellular processes like DNA replication, transcription, posttranscriptional processing, transport and translation in diverse organisms (Arya et al 2007;Feder and Hoffmann, 1999;Lindquist, 1986).…”