Evolution of pathogen-specific improved survivorship post-infection in populations of Drosophila melanogaster adapted to larval crowding

Abstract

The environment experienced by individuals during their juvenile stages has an impact on their adult stages. In holometabolous insects like Drosophila melanogaster, most of the resource acquisition for adult stages happens during the larval stages. Larval-crowding is a stressful environment, which exposes the larvae to scarcity of food and accumulation of toxic waste. Since adult traits are contingent upon larval stages, in larval-crowding like conditions, adult traits are prone to get affected. While the effect of resource limited, poor-developmental environment on adult immune response has been widely studied, the effect of adaptation to resource-limited developmental environment has not been studied, therefore in this study we assayed the evolution of ability to survive infection in adult stages as a correlated response to adaptation to larval crowding environments. Using four populations of Drosophila melanogaster adapted to larval crowding for 240 generations and their respective control populations, we show that populations adapted to larval crowding show an improved and evolved post-infection survivorship against a gram-negative bacteria Pseudomonas entomophila. Whereas, against a gram-positive bacteria Enterococcus faecalis, no difference in post-infection survivorship was observed across control and selected populations. In this study, we report the co-related evolution of pathogen-specific increased survivorship post-infection in populations of Drosophila melanogaster as a result of adaptation to larval crowding environment.

Uric acid metabolism modulates diet-dependent responses to intraspecific competition in Drosophila larvae

“…For instance, larvae developing in crowded conditions have upregulated expression of heat-shock proteins in response to the stress of the developmental environment, 20 , 21 , 22 which may be involved in a hormesis-like response that leads to increased lifespan and fitness benefits in broader ecological contexts. 21 , 23 , 24 , 25 …”

Perception of dead conspecifics increases reproductive investment in fruit flies

“…Female terminal investment in response to dead conspecifics could be favoured in ecological contexts characterized by density booms, where populations are susceptible to infectious outbursts. Firm evidence suggests that D. melanogaster has evolved to cope with such population dynamics (Behrman et al, 2015; Burant et al, 2019; Corbel et al, 2022; Goldschmidt et al, 1955; Paaby et al, 2014), and several drosophilids have evolved adaptations to increased susceptibility of pathogenic and/or parasitic infection during phases of high population density (Fellowes & Godfray, 2000; Kapila et al, 2021; Ye et al, 2009). We hence suggest that D. melanogaster responses to dead conspecifics may have evolved in response to extrinsic mortality cues that are typically encountered at high population densities in the wild.…”

“…At high population density, Drosophila are more susceptible to deadly infectious diseases that can cause mass mortality (Biganski et al, 2021; Ebbert, 1995; Fellowes & Godfray, 2000), and evolutionary adaptations to these types of infections are well documented in this genus (e.g. larval encapsulation in response to parasitoids; Fellowes & Godfray, 2000; Kapila et al, 2021; Ye et al, 2009).…”

Consequences of adaptation to larval crowding on sexual and fecundity selection in Drosophila melanogaster

“…Since larval crowding scenarios are common in nature and are known to affect adult traits (Bierbaum et al, 1989; Kapila, Kashyap, Gulati, et al, 2021; Kapila, Kashyap, Poddar, et al, 2021; Roper et al, 1996; Shenoi, Banerjee, et al, 2016), the effect of larval crowding and evolution under crowded larval environments on sexual selection is an important avenue of research. Crowding is especially important in holometabolous insects such as Drosophila , where adults lay eggs in ephemeral habitats and juveniles are largely restricted to compete at the egg‐laying sites (Atkinson, 1979).…”

“…Often, populations may be subjected to larval crowding over multiple generations. Larval crowding can generate stressful environments (Mueller et al, 1991; Prasad & Joshi, 2003) and impose selection not only on the larval but also the adult stages (Kapila, Kashyap, Gulati, et al, 2021; Kapila, Kashyap, Poddar, et al, 2021; Shenoi, Ali, & Prasad, 2016; Shenoi, Banerjee, et al, 2016). Recent studies show that sexual selection may impede adaptation to novel environments (Chenoweth et al, 2015), or environmental changes leading to maladaptation can disrupt how sexual selection acts (Martinossi‐Allibert et al, 2017, 2018).…”