Biology subjects

Malwade, A.

Publications and source records attributed to Malwade, A..

4 recordsLinked to original sources

bioRxiv2024

Costs of dispersal evolution under larval malnutrition

Dispersal is a key eco-evolutionary process, and the causes and consequences of its evolution have been well-studied. However, although dispersal depends critically on the nutritional status of organisms, it is unclear how malnutrition affects the evolution of life history and the behavior of organisms under selection for increased dispersal. To address this issue, we used four replicate laboratory populations of Drosophila melanogaster previously selected for increased dispersal for 66-67 generations on a protein-poor larval diet. Compared to the unselected controls, the selected populations had lower female body weight, fecundity, male desiccation resistance and mating propensity, but greater male locomotor activity and mating latency. There were no significant differences in aggression. We also compared our results qualitatively with those from a previous study on dispersal selection under a standard larval diet. Barring desiccation resistance, locomotor activity, and rest duration, all other traits investigated responded differently to dispersal selection between the poor and the standard larval nutritional regimes. These results show that the evolution of traits associated with dispersal can differ markedly depending on the nutrition available for the dispersing populations.

evolutionary biology↗

bioRxiv2024

Experimental evolution of Drosophila without its microbiome

In single-generation experiments, microbiome removal often affects multiple host traits. However, relatively little is understood about the long-term implications of living in a microbe-free environment. To address this question, we evolved four replicate laboratory populations of Drosophila melanogaster without microbes and compared their traits with corresponding control populations that were reared with microbiota. This comparison was done under two assay environments: with-microbes and microbe-free. Prior single-generation experiments on our populations had revealed that microbiota removal significantly affects multiple traits, which suggested that the flies were under strong selection pressure to adapt to the absence of microbes. However, contrary to our expectations, the selected populations underwent very modest changes even after 54-57 generations of selection. Moreover, the magnitude of change in trait values across the with- and without- microbe environments was less for the selected populations than for the controls. RNA-Seq on one of the evolutionary replicates revealed that compared to the control, some anti-microbial peptides (AMPs) in the selected population were up-regulated, while several heat shock proteins (HSPs) were down-regulated. These results suggest that robust host-microbiome integrations on short timescales can nevertheless be labile on longer timescales. We situate these results in the context of the "evolutionary addiction hypothesis" and the "hygiene hypothesis".

evolutionary biology↗

bioRxiv2023

Selection for dispersal under larval malnutrition results in a non-monotonic kernel in Drosophila melanogaster

Dispersal is a key strategy for organisms to track favorable conditions and a shifting global climate has necessitated its closer investigation. While the distribution of dispersal distances (i.e. dispersal kernel) influences several aspects of population ecology, it remains unclear how kernel features are themselves affected by environmental factors. The current study addresses this question using laboratory populations of Drosophila melanogaster selected for greater dispersal under a protein-deficient larval diet. Our results reveal that dispersal-selected populations initiate dispersal more often and travel further on average than unselected controls. Although there is a significant change in the overall kernel shape, selection has not led to a greater tendency for long-distance dispersal (LDD). This is contrary to the results from a previous study on dispersal evolution under standard nutrition. We also find that dispersal evolution under larval malnutrition leads to a non-monotonic dispersal kernel, with the highest frequencies at intermediate distances. The evolved shape of the dispersal kernel and the limited LDD phenotype therefore point to significant qualitative shifts in the evolution of the dispersal kernel due to a change in larval nutrition. Our results thus provide a starting point for further investigation of such context dependence in dispersal evolution.

evolutionary biology↗

bioRxiv2019

Adult crowding induces sexual dimorphism in chronic stress-response in Drosophila melanogaster

Stress-induced mood disorders such as depression and anxiety are sexually dimorphic in human beings. Studying behavioural stress-responses in non-human animal models can help better understand the behavioural manifestations of these disorders and the dimorphism in their prevalence. Here we explore how sexes show differential behavioural responses to different chronic stressors, both abiotic and biotic, by using outbred populations of Drosophila melanogaster. The behaviours studied - namely, anhedonia, motivation to explore a novel habitat, locomotor activity and sleep levels - have been well-investigated in human and rodent-based models of stress disorders. These behaviours were studied in the context of two different stressors - mechanical perturbation and adult crowding. Responses to stress were found to be sexually dimorphic, and stressed females showed more behavioural changes, such as a reduced motivation to explore a novel habitat. Furthermore, adult crowding caused a greater number of sexually dimorphic behavioural changes than mechanical perturbation. For instance, while mechanical perturbation caused anhedonia across sexes, only females were anhedonic after crowding. We thus make a case for Drosophila melanogaster as a model system for studying sexual dimorphism in stress-induced mood disorders in humans.\n\nSUMMARY STATEMENTFemale fruit flies, like their human counterparts, are more prone to chronic stress-induced mood disorders like anhedonia or reduced activity. This sexual dimorphism was more evident in a biotic stress.

ecology↗