DOI: 10.5061/dryad.1rn8pk14w
title: Life-history trade-offs and stress resistance in Drosophila melanogaster populations adapted to pathogenic bacterial infection

description: Evolution of increased immune defence is often limited by costs:
 correlated changes in other traits (viz. life-history traits) that
 otherwise reduce the fitness of the host organisms. Experimental evolution
 studies are useful for understanding the evolution of immune function, and
 correlated changes in other traits. We experimentally evolved
 replicate Drosophila melanogaster populations to better
 survive infection challenge with an entomopathogenic
 bacteria, Enterococcus faecalis. Within 35 generations of
 directional selection, selected populations showed marked increase in
 post-infection survival compared to ancestrally paired controls. We next
 measured various life-history traits of these populations. Our results
 show that the selected populations do not differ from control populations
 for larval development time and body weight at eclosion. No difference is
 also observed in case of fecundity and longevity (following the acute
 phase of infection), either when the flies were subjected to infection or
 when the flies were uninfected; although infected flies from all
 populations die much earlier compared to uninfected flies. Selected
 populations are either equally good, or occasionally better, as the
 control populations at surviving abiotic stressors (starvation and
 desiccation), although infected flies from all populations are more
 susceptible to stress than uninfected flies. Therefore, we conclude that
 (a) D. melanogaster populations can rapidly evolve to be
 more immune to infection with E. faecalis; (b) evolution of
 increased defence against E. faecalis entails no
 life-history cost for the hosts; and (c) evolving defence against a biotic
 threat (pathogen) does not make flies more susceptible to abiotic
 stressors.
description: Life-history traits, and resistance to biotic and abiotic
 stressors, were measured for <em>Drosophila melanogaster</em>
 flies selected for improved post-infection survival against systemic
 infection with an entomopathogenic, Gram-positive bacteria,
 <em>Enterococcus faecalis</em>. The populations were named the
 <em>EPN populations</em>. <em>1.
 </em><em>EPN populations: history and maintenance
 regime</em> The EPN populations was derived from
 ancestral Blue Ridge Baseline (BRB) populations (Singh et al., 2021). The
 BRB populations consist of 4 replicate outbred populations, originally
 established by hybridizing iso-female lines which had themselves been
 established by wild-caught flies, from Blue Ridge, USA, in the laboratory
 of Prof. Daniel Promislow (Singh et al., 2015). These populations are
 maintained in a 14-day discrete generation cycle, with a census size of
 about 2800 adults in every generation. These populations are maintained
 under standard lab conditions (12:12 light: dark cycle, 25 °C, 60%
 relative humidity) on banana-jaggery-yeast food medium. Full details of
 maintenance of BRB populations are described in Singh et al.,
 2015. From each replicate population of
 BRB<sub>1-4 </sub>three populations were derived: (i)
 E<sub>1-4</sub>, infected with <em>Enterococcus
 faecalis</em>; (ii) P<sub>1-4</sub>, procedural control;
 and (iii) N<sub>1-4</sub>, uninfected control. Populations
 having same numeral subscript shared a common recent ancestry and were
 treated as independent blocks (block 1, block 2 and so forth). Individual
 blocks were always handled together during selection and during
 experiments. Eggs were collected at a density of ~70 eggs per vial (25mm
 diameter × 90 mm height) containing 6-8 ml of standard
 banana-jaggery-yeast food. Ten 10 such vials were collected for each
 population. These vials were reared under standard laboratory (12:12
 light: dark cycle, 25 °C, 60% relative humidity) conditions until
 12<sup>th</sup> day post egg collection. By
 10<sup>th</sup> day all flies eclose and had mated at least
 once by 12<sup>th</sup> day (day of infection). Further
 handling depended on the type of population. For E
 populations, on 12<sup>th</sup> day post egg collection, every
 generation 200 females and 200 males were randomly picked out of total 700
 flies. These flies were pricked on the dorsolateral surface of the thorax
 with Minutien pin (0.1mm Fine Scientific Tools, USA) dipped in bacterial
 suspension under light CO<sub>2</sub> anaesthesia (refer
 section 2.2 Bacterial culture, for details). After infection flies were
 placed inside plexiglass cage (14 cm length x 16 cm width x 13 cm height)
 with food in 60 mm Petri plate. About fifty percent of the infected flies
 die within 96 hours of infection (mortality ranged from minimum 40% to
 maximum 55% across different E populations across generations). Post 96
 hours, fly cages were provided with oviposition food plates for 18 hours.
 Eggs were collected from these oviposition plates at a density of ~70 eggs
 per vial (as mentioned above) to start next generation. This 18-hour
 window, 96 hours after infection, serves as the selection window for the
 EPN populations. The eggs produced by the surviving flies from each
 population during this window is used to set up the next
 generation. Similarly, for P populations, 100 females
 and 100 males out of total 700 flies are pricked every generation with
 Minutien pin dipped in sterile 10 mM MgSO<sub>4 </sub>under
 light CO<sub>2</sub> anaesthesia. For N populations, 100
 females and 100 males out of total 700 flies are sorted every generation
 under light CO<sub>2</sub> anaesthesia and transferred to the
 plexiglass cage. Aside from the infection treatment differences, E, P, and
 N populations were treated the same. Post 96 hours, eggs are collected in
 similar way as for E populations to start the next generation.
 The E populations are initiated every generation with double the
 number of adults compared to P or N populations to account for the fact
 that about 50% of the E populations perish due to infection every
 generation. There is negligible mortality in P (&lt; 2%) and N
 (&lt; 1%) populations. This ensured that the census sizes of the
 populations remain similar on average across generations.
 <em>2. </em><em>Bacterial
 culture</em> The pathogen used in this study was
 the Gram-positive bacterium <em>Enterococcus faecalis</em>
 (Ef, Gram-positive, grown at 37 °C, Lazzaro et al 2006). <em>E.
 faecalis</em> is an entomopathogen commonly used in
 eco-immunological studies in Drosophila melanogaster (Troha and Buchon
 2019) and is known to establish persistent infection in flies (Chambers et
 al., 2019). Natural populations are known to harbour genetic variation for
 resistance against <em>E. faecalis</em> (Lazzaro et al., 2006,
 Chapman et al., 2020), and its virulence mechanisms and the host responses
 it elicits have been described in some detail (Gobert et al., 2003,
 Shirasu-Hiza and Schneider 2007, Ayres and Schneider 2008, Dionne and
 Schneider 2008, Nehme et al., 2011, Hanson et al., 2019). <em>E.
 faecalis</em> is also a common member of natural microflora of
 various insects (Cox and Gilmore 2007), and the pathogen isolate used in
 this study was originally derived from a wild-caught <em>D.
 melanogaster</em> (Lazzaro et al., 2006). The
 bacterial stocks are maintained as 17% glycerol stocks frozen at -80 °C.
 An overnight primary culture of bacteria was set by inoculating a stab of
 bacterial glycerol stock in 10 ml lysogeny broth (Luria-Bertani-Miller,
 HiMedia) and incubating it at appropriate temperature with continuous
 mixing at 150 RPM (revolution per minute). Once this primary culture
 turned confluent (OD<sub>600 </sub>= 1.0-1.2), a secondary
 culture was set up (100 microliters of primary culture in 10 ml fresh
 lysogeny broth) and maintained at appropriate temperature with continuous
 mixing until it turned confluent again. (The OD<sub>600</sub>
 for the primary and secondary cultures were monitored during their growth
 to ensure that the cultures were not overgrown.) This secondary culture
 was centrifuged, and bacterial pellets were resuspended in sterile 10 mM
 MgSO<sub>4</sub> buffer to obtain desired
 OD<sub>600</sub> for infection. This bacterial suspension was
 used to infect flies. Infection was done by dipping needle in the
 bacterial suspension or sterile 10mM MgSO<sub>4</sub> buffer
 and pricking flies on the thorax. The bacterial suspension was vortexed
 both prior to and during infection at regular intervals to prevent
 bacterial cells from settling. For stock maintenance, E
 populations of EPN regime were infected with <em>E.
 faecalis</em>. Throughout the selection history of EPN, the pathogen
 infection dose was modulated to induce fifty percent mortality in E
 populations. This ensured a constant, directional selection process. The
 dose for fifty-percent mortality was originally determined for the
 ancestral BRB populations by infecting them with different doses, where we
 found that OD<sub>600</sub> = 0.8 reproducibly led to 50%
 (±5%) mortality. Hence, E populations were initiated by infecting the
 flies at this dose. During regular maintenance, the exact mortality in E
 populations were monitored every 3-4 generations. By generation 20, the
 mortality in these populations had come down to 40%, and hence the
 infection dose was increased to OD<sub>600</sub> = 1.0 from
 generations 21 onwards. <em>3.
 </em><em>Fly standardization</em>
 Experimental eggs were collected from flies that were cultured
 under common environmental conditions for one generation. This was done to
 account for any non-genetic parental effects (Rose 1984) and flies thus
 generated were called standardized flies. Experimental
 eggs were collected from all three populations (E, P, and N) at a density
 of ~70 eggs per vial and 10 such vials were established per population.
 The eggs were reared in the same development vials into adults, until day
 12 PEL. These adults were then transferred to plexiglass cages (14x16x13
 cm<sup>3</sup>) with food in Petri plates (60 mm diameter).
 Experimental eggs were collected from these population cages.
 <em>4. Post-infection survival and longevity
 </em> Standardized fly cages for each population
 (E<sub>i</sub>, P<sub>i</sub>, and
 N<sub>i</sub>, where ‘i’ represents blocks 1-4) were provided
 with <em>ad libitum</em> yeast paste smeared on the top of the
 standard banana-jaggery-yeast food plate, three days prior to the egg
 collection. After two days, these yeasted food plates were replaced with
 oviposition plates for 18 hours. Eggs were collected from these
 oviposition plates at the density of approximately 70 eggs per vial, into
 25 vials per population (E<sub>i</sub>,
 P<sub>i</sub>, and N<sub>i</sub>), with each vial
 containing 8 ml of banana-jaggery-yeast food. These
 <em>rearing</em> vials were incubated at standard maintenance
 conditions for next 12 days. Flies generally eclose by
 10<sup>th</sup>-11<sup>th</sup> day
 post-egg-laying (PEL) in the rearing vials, and mate at least once by
 12<sup>th</sup> day PEL. On
 12<sup>th</sup> day PEL, flies from each of the
 E<sub>i</sub>, P<sub>i</sub>, and
 N<sub>i</sub> populations were randomly assigned to one of the
 three treatments: (a)   <em>infected</em>
 treatment: 200 females and 200 males were randomly sampled from each
 population and were infected with <em>E. faecalis</em> at
 OD<sub>600 </sub>= 0.8 under light CO<sub>2</sub>
 anaesthesia; (b)  <em>sham-infected</em>
 treatment: 100 females and 100 males were randomly sampled from each
 population, and sham-infected with sterile needle dipped in sterile 10 mM
 MgSO<sub>4</sub> solution; and, (c)  
 <em>uninfected</em> treatment: 100 females and 100 males were
 just randomly sampled under light CO<sub>2</sub> anaesthesia,
 and not subjected to any further manipulation. After
 being subjected to different treatments, the flies were housed in
 plexiglass cages (14 cm × 16 cm × 13 cm) having <em>ad
 libitum</em> access to banana-jaggery-yeast food provided in Petri
 plates (60 mm diameter). Individual blocks were experimented upon on
 separate days. Survivorship of the flies was monitored
 every 4-6 hours for the first 96 hours after infection, and after this
 period, mortality in the cages was recorded once a day until the last fly
 died in all cages. About fifty percent of the infected fly and almost all
 sham-infected and uninfected flies survived post 96-hours window. Fresh
 food plates were provided on alternate days. Altogether, 200
 flies/sex/population/block were infected with <em>E.
 faecalis,</em> 100 flies/sex/population/block were sham-infected,
 and 100 flies/sex/population/block were maintained as uninfected
 controls. <em>5. Fecundity and hatchability
 </em> We measured the number of eggs produced by
 the females (fecundity) from the EPN populations, and what proportion of
 these eggs produced viable larva (hatchability), to test for the effect of
 selection history and infection status on fecundity and hatchability. The
 same experimental cages that were used for assaying post-infection
 survival was used here for measuring fecundity and hatchability.
 Fecundity was assayed after 96 hours of infection treatment
 (identical to the time when eggs are collected for the next generation
 during maintenance of the selection regime). Each of the population cages
 (E<sub>i</sub>, P<sub>i</sub>, and
 N<sub>i</sub> flies either infected, sham-infected, or
 uninfected) were provided with an oviposition plate (60 mm diameter),
 containing standard banana-jaggery-yeast food, for the female flies to lay
 eggs on for 18 hours. After 18 hours, these plates were withdrawn,
 labelled with the cage identity, and stored at -20˚C for eggs to be
 counted later. Eggs on the surface of the food plates were counted
 visually using a light stereo microscope (Zeiss Stemi 2000) under 2.5X ×
 10X magnification. Per-female fecundity was calculated by dividing the
 number of eggs laid by the females during 18-hour window by the number of
 females alive in the respective cages at the start of the oviposition
 period. Hatchability was assayed after 114 hours of
 infection. Following withdrawal of the oviposition plates, each of the
 above cages were provided with a fresh food plate (60 mm diameter) for 8
 hours. From each of these plates (each coming from a single cage), three
 samples of 100 eggs each was picked using a moist paint brush and arranged
 onto the surface of three separate agar plates (90 mm Petri plates, 1.5%
 agar). These plates were incubated under standard laboratory maintenance
 conditions, and 48 hours later, the number of eggs on each agar plate that
 had hatched were visually counted using a light stereo microscope (Zeiss
 Stemi 2000) under 2.5X × 10X magnification. Hatchability was determined
 for each agar plate by dividing the number of eggs that hatched by the
 total number of eggs that were placed on the surface of that plate and was
 used as unit of replication. Altogether from each cage 3 × 100
 eggs/treatment/population/block were scanned for hatchability.
 <em>6. Egg-to-adult development time and viability, and dry
 body weight</em> Fresh food plates with excess
 live yeast paste were provided to the standardised population cages
 (E<sub>i</sub>, P<sub>i</sub>, an
 N<sub>i</sub>) for 48 hours. Following this, a fresh food
 plate with live yeast paste (yeast paste placed at the centre of the plate
 and with space around the circumference for females to lay eggs) was
 provided to each cage for 6 hours. This plate was followed up with two
 more similarly yeasted food plates, each for a 1-hour window. This was
 done to encourage the females to lay any stored eggs. After this a fresh
 food plate was provided to each cage for females to lay eggs on for an
 hour, and eggs were collected using a light stereo microscope (Zeiss Stemi
 2000) under 2.5X × 10X magnification and distributed into food vials (with
 8 ml of banana-jaggery-yeast food) at an exact density of 70 eggs per
 vial. 10 vials were set up for each population (E<sub>i</sub>,
 P<sub>i</sub>, an N<sub>i</sub>), and blocks were
 handled on separate days. These vials were incubated under standard
 maintenance conditions, and when flies started eclosing, freshly eclosed
 flies were transferred to empty glass vials every 4 hours, and frozen at
 -20 °C for further processing; this was done till the very last pupae had
 eclosed. The storage vials were labelled so as to preserve parent vial,
 population, and block identities. The flies eclosed at each time window
 from each vial was later scored visually using a light stereo microscope
 (Zeiss Stemi 2000) under 2.5X × 10X magnification to enumerate the total
 number and sex of the flies eclosed in that time window. Therefore, for
 each vial, the data was available for the number of males and females that
 eclosed at each time window, and the total number of flies that eclosed
 out of the vial. The median development time was calculated as the time
 taken by half of flies of each sex to eclose (starting for the time of
 oviposition), and viability was calculated by dividing the total number of
 flies eclosed by the number of eggs seeded in the vial (which was 70
 eggs). After enumeration, the flies were put back into -20 ˚C storage for
 further use. Flies preserved from the development time
 assay were used for measuring dry body weight at eclosion. All flies
 eclosing out of a single parent vial were pooled together; hence there
 were 10 pools of flies per population per block. From each pool, 5 females
 and 5 males were randomly sampled and placed in 1.5 ml micro-centrifuge
 tubes (MCTs); females and males were placed in separate MCTs. Therefore,
 each vial used in the development time assay yielded one MCT with 5 males
 and one MCT with 5 females. These MCTs were dry heated in a hot air oven
 for 48 hours at 60 ˚C to eliminate all moisture. The flies were then
 weighed using Sartorius weighing balance (model CPA225D, least count
 0.01mg).  Individual blocks were handled on separate days. Dry body weight
 was measured for only 3 blocks because samples of block 2 was lost in
 handling. <em>7. Starvation resistance 
 </em> Eggs were collected from standardised
 population cages at an approximate density of 70 eggs per vial. 20 such
 vials were collected for each population (E<sub>i</sub>,
 P<sub>i</sub>, an N<sub>i</sub>), and reared under
 standard maintenance conditions. Adults were housed in the rearing vials
 until 12<sup>th</sup> day PEL. By this time all flies were
 sexually mature and have mated at least once inside the rearing vials
 itself. On 12<sup>th</sup> day PEL, flies from each population
 (E<sub>i</sub>, P<sub>i</sub>, an
 N<sub>i</sub>) were randomly assigned to three
 treatments: (a)   <em>infected</em>
 treatment: 50 females and 50 males were randomly sampled from each
 population, and were infected with <em>E. faecalis</em> at
 OD<sub>600 </sub>= 0.8 under light CO<sub>2</sub>
 anaesthesia; (b)  <em>sham-infected</em>
 treatment: 50 females and 50 males were randomly sampled from each
 population, and sham-infected with sterile needle dipped in sterile 10 mM
 MgSO<sub>4</sub> solution; and, (c)  
 <em>uninfected</em> treatment: 50 females and 50 males were
 just randomly sampled under light CO<sub>2</sub> anaesthesia,
 and not subjected to any further manipulation. After
 being subjected to treatments, the flies were housed in vials containing 2
 ml 1.5% non-nutritive agar gel, at a density of 10 females (or, males) per
 vial. The sexes were housed separately. The presence of agar gel in the
 vials ensured that the flies had <em>ad libitum</em> access to
 water during the course of the starvation assay. Individual blocks were
 assayed upon on separate days. In total, 5
 vials/sex/treatment/population/block were set up for this assay. The vials
 were monitored every 6-8 hours to record the number of dead flies, until
 the last fly perished. Surviving flies were transferred to fresh agar
 vials every 48 hours. <em>8. Desiccation
 resistance</em> A set-up identical to the
 starvation resistance assay was utilised to test for desiccation
 resistance; the only difference was that the flies, after being subjected
 to their respective treatments, were housed in empty vials (no food or
 agar gel). Additionally, 5 gm silica beads were placed in each vial (above
 the cotton plug; no direct contact between flies and silica), and the
 mouth of the vial was sealed off with parafilm tape, to eliminate moisture
 from the vials. Individual blocks were assayed upon on separate days. In
 total, 5 vials/sex/treatment/population/block were set up for this assay.
 The vials were monitored every 1.5 hours to record the number of dead
 flies, until the very last fly perished. <em>9.
 Statistical analysis </em> All analysis was
 performed using R statistical software, version 4.1.0 (R Core Team 2021).
 For survival analysis, mixed-effect Cox-proportional hazard models were
 fitted to the survival data (from post-infection survival, longevity,
 starvation resistance, and desiccation resistance assays) using the
 <em>coxme</em> function of the “coxme” package (Therneau
 2020), and the confidence intervals for these models were calculated using
 <em>confint</em> function of the base R package. These models
 were subjected to Analysis of Deviance using <em>Anova
 </em>function from the “car” package. Survival curves were plotted
 using the <em>ggsurvplot</em> function of the “survminer”
 package (Kassambara et al 2021) after modelling the data using
 <em>survfit</em> function from the “survival” package
 (Therneau 2021). <em>Post-infection survival
 assay (first 96 hours following infection):</em> We first modelled
 survival of all flies with a Cox model with <em>infection
 treatment</em> (uninfected, sham-infected, infected),
 <em>selection history</em> (populations N, P, and E),
 <em>sex</em> (females and males), and their pair-wise
 interactions as fixed factor and <em>block </em>as a random
 factor. Thereafter, we stratified the data by <em>infection
 treatment</em>, fitted a model with <em>selection
 history</em>, <em>sex</em>, and their interaction as
 fixed factor, and <em>block</em> as a random factor.
 Significance testing of all models were done using Analysis of
 Deviance. Longevity assay (survival from 96 hours
 post-infection and onwards), starvation resistance assay, and desiccation
 resistance assay: We first modelled survival of all flies with a Cox model
 with <em>infection treatment</em> (uninfected, sham-infected,
 infected), <em>selection history</em> (populations N, P, and
 E), <em>sex</em> (females and males), and their pair-wise
 interactions as fixed factor and <em>block </em>as a random
 factor. Thereafter, we stratified the data by <em>sex</em>,
 fitted a model with <em>selection history</em>,
 <em>infection treatment</em>, and their interaction, and
 <em>block</em> as a random factor. Further stratifications
 were done wherever any interaction term had a significant effect.
 Significance testing of all models were done using Analysis of
 Deviance.  Data from life-history traits were modelled
 using mixed-effects general linear models (<em>lmer</em>
 function from “lmerTest” package; Kuznetsova et al 2017) and then
 subjected to type-III Analysis of Variance (ANOVA;
 <em>anova</em> function from base R package) for significance
 tests. Pairwise comparisons wherever necessary was done using Tukey’s HSD
 (<em>lsmeans</em> function from “emmeans” package; Lenth
 2021). The mixed-effects general linear models used were:
 Fecundity ~ selection history + infection treatment + selection
 history:infection treatment + (1|block), Hatchability ~
 selection history + infection treatment + selection history:infection
 treatment + (1|block), Development time ~ selection
 history + sex + selection history:sex + (1|block),
 Viability ~ selection history + (1|block), 
 Body weight ~ selection history + sex + selection history:sex +
 (1|block).
description: # Life-history trade-offs and stress resistance in Drosophila melanogaster
 populations adapted to pathogenic bacterial infection
 [https://doi.org/10.5061/dryad.1rn8pk14w](https://doi.org/10.5061/dryad.1rn8pk14w) ## Description of the data and file structure **GENERAL INFORMATION** 1\. Title of Dataset: "Life-history trade-offs and stress resistance in Drosophila melanogaster populations adapted to pathogenic bacterial infection" 2\. Author Information A. Principal Investigator Contact Information Name: Prof. N. G. Prasad Institution: Indian Institute of Science Education and Research, Mohali Address: IISER Mohali, Sector 81, Knowledge City, SAS Nagar, Punjab - 140306, India. Email: [prasad@iisermohali.ac.in](mailto:prasad@iisermohali.ac.in) B. Associate or Co-investigator Contact Information Name: Aparajita Singh Institution: Indian Institute of Science Education and Research, Mohali Address: IISER Mohali, Sector 81, Knowledge City, SAS Nagar, Punjab - 140306, India. Email: [aparajita08@gmail.com](mailto:aparajita08@gmail.com) C. Associate or Co-investigator Contact Information Name: Aabeer Basu Institution: Indian Institute of Science Education and Research, Mohali Address: IISER Mohali, Sector 81, Knowledge City, SAS Nagar, Punjab - 140306, India. Email: [aabeerkbasu@gmail.com](mailto:aabeerkbasu@gmail.com) 3\. Duration of data collection: 2018-2019 4\. Geographic location of data collection: Mohali, Punjab, India 5\. Information about funding sources that supported the collection of the data: IISER Mohali, Govt. of India, and research grant no. BT/PR14278/BRB/10/1417/2015 from Dept. of Biotechnology, Govt. of India. ### Files and variables #### File 1: epnDevTime.csv **Description:** This file ("epnDevTime.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnDevTime.csv" Note: This file contains data for egg-to-adult development time for females and males from the E, P, and N populations (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 5 2\. Number of cases/rows: 237 3\. Variable List: Block (Block identity of the host.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) Sex (Sex of the host: “Male”, “Female”.) VialID (Vial identity; also, the unit of replication.) MedianTime (Median time to eclosion for flies of each sex in each vial, expressed in hours.) ##### Variables * Selection: * Block: * VialID: * Sex: * MedianTime: #### File 2: epnBodyWeight.csv **Description:** This file ("epnBodyWeight.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnBodyWeight.csv" Note: This file contains data for dry body weight of adult females and males from the E, P, and N populations (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 5 2\. Number of cases/rows: 181 3\. Variable List: Block (Block identity of the host.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) Sex (Sex of the host: “Male”, “Female”.) VialID (Vial identity; also, the unit of replication.) DryBodyWt (Dry body weight of adult flies expressed in mg.) ##### Variables * Selection : * Block: * VialID: * Sex: * DryBodyWt: #### File 3: epnDesiccation.csv **Description:** This file ("epnDesiccation.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnDesiccation.csv" Note: This file contains data for post-infection survival of E, P, and N populations when flies are subjected to concurrent desiccation from the point of infection onwards (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 6 2\. Number of cases/rows: 3601 3\. Variable List: Treatment (Infection treatments: “Infected” denotes flies infected with Enterococcus faecalis, “Sham” denotes flies subjected to sham-infection, “Uninfected” denotes flies that were not subjected to any infection treatment.) Block (Block identity of the host.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) Sex (Sex of the host: “Male”, “Female”.) Time (Time in hours at which the event (death/censor) was recorded.) Status (Status of the fly at the time the event was recorded: "1" denotes mortality, "0" denotes right-censored data.) ##### Variables * Selection: * Block: * Treatment: * Sex: * Time: * Status: #### File 4: epnFecundity.csv **Description:** his file ("epnFecundity.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnFecundity.csv" Note: This file contains data for fecundity of females from E, P, and N populations when they are subjected to different infection treatments (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 4 2\. Number of cases/rows: 37 3\. Variable List: Treatment (Infection treatments: “Infected” denotes flies infected with Enterococcus faecalis, “Sham” denotes flies subjected to sham-infection, “Uninfected” denotes flies that were not subjected to any infection treatment.) Block (Block identity of the host.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) Fecundity (Eggs per female: total number of eggs laid in a cage in the fecundity window divided by the number of females surviving in the cage at the start of the fecundity window.) ##### Variables * Selection: * Treatment: * Block: * Fecundity: #### File 5: epnE2AViability.csv **Description:** This file ("epnE2AViability.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnE2AViability.csv" Note: This file contains data for egg-to-adult viability for flies from the E, P, and N populations (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 4 2\. Number of cases/rows: 119 3\. Variable List: Block (Block identity of the host.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) VialID (Vial identity; also, the unit of replication.) ProportionViability (Proportion of eggs in each vial that successfully developed into adults.) ##### Variables * Selection: * Block: * VialID: * ProportionViability: #### File 6: epnHatchability.csv **Description:** This file ("epnHatchability.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnHatchability.csv" Note: This file contains data for hatchability of eggs produced by females from E, P, and N populations when they are subjected to different infection treatments (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 5 2\. Number of cases/rows: 109 3\. Variable List: Treatment (Infection treatments: “Infected” denotes flies infected with Enterococcus faecalis, “Sham” denotes flies subjected to sham-infection, “Uninfected” denotes flies that were not subjected to any infection treatment.) Block (Block identity of the host.) Replicate (Replicate number; unit of replication. Represents identity of agar plates used for assaying hatchability.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) Hatchability (Proportion of eggs that hatched within 48 hours of eggs being collected from females.) ##### Variables * Selection: * Block: * Treatment: * Replicate: * Hatchability: #### File 7: epnStarvation.csv **Description:** This file ("epnStarvation.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnStarvation.csv" Note: This file contains data for post-infection survival of E, P, and N populations when flies are subjected to concurrent starvation from the point of infection onwards (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 6 2\. Number of cases/rows: 3563 3\. Variable List: Treatment (Infection treatments: “Infected” denotes flies infected with Enterococcus faecalis, “Sham” denotes flies subjected to sham-infection, “Uninfected” denotes flies that were not subjected to any infection treatment.) Block (Block identity of the host.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) Sex (Sex of the host: “Male”, “Female”.) Time (Time in hours at which the event (death/censor) was recorded.) Status (Status of the fly at the time the event was recorded: "1" denotes mortality, "0" denotes right-censored data.) ##### Variables * Selection: * Block: * Treatment: * Sex: * Time: * Status: #### File 8: epnLongevity.csv **Description:** This file ("epnLongevity.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnLongevity.csv" Note: This file contains data for post-infection survival of E, P, and N populations from 96-hours post-infection onwards till the very last fly survived (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 6 2\. Number of cases/rows: 6782 3\. Variable List: Treatment (Infection treatments: “Infected” denotes flies infected with Enterococcus faecalis, “Sham” denotes flies subjected to sham-infection, “Uninfected” denotes flies that were not subjected to any infection treatment.) Block (Block identity of the host.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) Sex (Sex of the host: “Male”, “Female”.) Time (Time in days at which the event (death/censor) was recorded.) Status (Status of the fly at the time the event was recorded: "1" denotes mortality, "0" denotes right-censored data.) ##### Variables * Selection: * Block: * Treatment: * Sex: * Time: * Status: #### File 9: epnSurvival.csv **Description:** This file ("epnSurvival.csv") was generated in 2018-2019 by Aparajita Singh and others at the Evolutionary Biology Lab, Department of Biological Sciences, IISER Mohali. DATA & FILE OVERVIEW File Name: "epnSurvival.csv" Note: This file contains data for post-infection survival of E, P, and N populations for first 96 hours following infection (as described in the above cited bioRxiv pre-print). 1\. Number of variables: 6 2\. Number of cases/rows: 9601 3\. Variable List: Treatment (Infection treatments: “Infected” denotes flies infected with Enterococcus faecalis, “Sham” denotes flies subjected to sham-infection, “Uninfected” denotes flies that were not subjected to any infection treatment.) Block (Block identity of the host.) Selection (Selection history of the host: “E” denotes flies from the selected populations, “P” denotes flies from the sham-infected control populations, “N” denotes flies from the uninfected control populations.) Sex (Sex of the host: “Males”, “Females”.) Time (Time in hours at which the event (death/censor) was recorded.) Status (Status of the fly at the time the event was recorded: "1" denotes mortality, "0" denotes right-censored data.) ##### Variables * Treatment: * Block: * Selection: * Sex: * Time: * Status: ## Code/software Not Applicable Other publicly accessible locations of the data: * Not Applicable Data was derived from the following sources: * Not Applicable