DOI: 10.5061/dryad.sn02v6xjz
title: Data from: Desert lizards modulate their nutritional responses to match seasonal biological needs

description: Animals in extreme environments, such as deserts, experience severe
 seasonal fluctuations in abiotic conditions and resources. Under these
 conditions, they must obtain macronutrients in optimal amounts and ratios
 to meet their nutritional requirements, which themselves vary with
 seasonal changes in physiological and life-history processes. To
 understand whether nutritional intakes and retention align with key
 life-history events across seasons, we examined the nutritional ecology of
 the desert-dwelling lizard Saara hardwickii. We first measured seasonal
 variation in the quantity and quality of plants available for these
 herbivorous lizards. By combining field observations of foraging behaviour
 with elemental analysis, we determined carbon (C) and nitrogen (N) levels
 in dietary intakes and faecal matter across seasons. Intake C: N was
 lowest and faecal C: N highest in June, reflecting greater proportional
 consumption and retention of N, likely meeting increased protein demands
 during breeding. Conversely, dietary C: N and faecal %N were highest in
 October, indicating greater consumption and retention of C prior to
 hibernation. Surprisingly, these putative herbivores consumed insects only
 around the breeding season, despite their year-round availability.
 Overall, we show that S. hardwickii employs both behavioural diet choice
 and post-ingestive physiology to match seasonal nutritional needs by
 differentially consuming and retaining nutrients in an extreme
 environment.
description: We sampled <em>S. hardwickii</em> from April to
 October 2022 in Jorbeer-Gadhwala Conservation Reserve, Rajasthan, India.
 All measurements were repeated in the same 20 plots of 20x20m across four
 seasons - April, June, August, and October. Since these desert lizards are
 known to be herbivorous, we estimated the plant species composition and
 wet biomass by setting up 20 smaller quadrats of 1x1m in each of the
 larger sampling plots. We carried out behavioural focal observations in a
 separate sampling plot each day and recorded all the items and their
 amounts consumed by these lizards throughout the day. At the end of focal
 observations, we collected samples of all the consumed food items from the
 same plot to measure the nutritional composition of each dietary
 component. We also collected fresh faecal pellets from each plot to
 estimate their elemental composition and infer about retained nutrients.
 Elemental composition was measured for all the dietary components and
 faecal matter, and this information was combined with behavioural data to
 estimate the nutritional composition of diets across seasons (N =
 20/season). 
description: # Data from: Desert lizards modulate their nutritional responses to match
 seasonal biological needs Dataset DOI:
 [10.5061/dryad.sn02v6xjz](https://doi.org/10.5061/dryad.sn02v6xjz) ##
 Description of the data and file structure **Research permission and
 ethical approval:** *Saara hardwickii* is protected under Indian Wildlife
 Protection Act (1972), so we acquired the Rajasthan Forest Department
 permit to work in Jorbeer Gadhwala Conservation Reserve and collect plant
 and faecal samples. Since all our data on this species was observational,
 we did not need any ethical approval for this study. 
 
 ### Files and variables #### File:
 datasets_seasonal_nutritional_responses_in_desert_lizards.xlsx
 **Description of data and file structure (Sheet1):** This datasheet
 contains raw measurements of %C, %N, and C:N of all the components in
 *S.hardwickii* diets across seasons. ##### Variables * season: four
 sampling seasons - April, June, August, and October * Diet component: all
 the plant species available for the lizards to eat in their habitat, and
 the insects they consumed across the four seasons * C: N: carbon to
 nitrogen ratios for each dietary component * %C: proportion of elemental
 carbon in the dietary component *  %N: proportion of elemental nitrogen in
 the dietary component **Description of data and file structure (Sheet2):**
 This datasheet contains data on wet biomass, species composition, and
 relative abundance of all the plant species consumed by *S.
 hardwickii* across seasons. **Variables** * seasons: four sampling seasons
 -April, June, August, and October * biomass (g/sqm): total mass of all the
 grasses and herbs present in 1a  square meter area under the quadrat *
 total biomass (g/400sqm): calculated biomass for the entire sampling plot
 of 20 x 20 meters * dact: mean percentage area of the quadrat covered by
 *Dactyloctenium* sp. * euph: mean percentage area of the quadrat covered
 by *Euphorbia* sp. * helio: mean percentage area of the quadrat covered by
 *Heliotropium* sp. * aerva: mean percentage area of the quadrat covered by
 *Aerva* sp. * sum: total percentage area covered by all the plants * %d:
 proportion of the total biomass constituted by *Dactyloctenium* sp. * %e:
 proportion of the total biomass constituted by *Euphorbia* sp. - %h:
 proportion of the total biomass constituted by *Heliotropium* sp. - %a:
 proportion of the total biomass constituted by *Aerva* sp. - d: absolute
 biomass of *Dactyloctenium* sp. in the plot - e: absolute biomass of
 *Euphorbia* sp. in the plot - h: absolute biomass of *Heliotropium* sp. in
 the plot - a: absolute biomass of *Aerva* sp. in the plot **Description of
 data and file structure (Sheet3):** This datasheet contains raw data for
 bite counts of all food items consumed by *S. hardwickii* across seasons.
 **Variables** * plot: plot IDs for all the plots marked for sampling
 across seasons * season: four sampling seasons - April, June, August, and
 October * dact_bc: absolute number of bite counts of *Dactyloctenium* per
 day * euph_bc: absolute number of bite counts of *Euphorbia* per day *
 helio_bc: absolute number of bite counts of *Heliotropium* per day *
 aerva_bc: absolute number of bite counts of *Aerva* per day * insects_bc:
 absolute number of bite counts of insects per day **Description of data
 and file structure (Sheet 4):** This datasheet contains data on diet
 composition and the contribution of each food item to the diet of *S.
 hardwickii* across seasons. **Variables** * plot: plot IDs for all the
 plots marked for sampling across seasons * season: four sampling seasons
 -April, June, August, and October * dact_g: amount of *Dactyloctenium*
 consumed per day in grams * euph_g: amount of *Euphorbia* consumed per day
 in grams * helio_g: amount of *Heliotropium* consumed per day in grams *
 aerva_g: amount of *Aerva* consumed per day in grams * insects_g: amount
 of insects consumed per day in grams * total (g): total biomass consumed
 per day in grams * dact_%m: proportion of the total biomass constituted by
 *Dactyloctenium* * euph_%m: proportion of the total biomass constituted by
 *Euphorbia* * helio_%m: proportion of the total biomass constituted by
 *Heliotropium* * aerva_%m: proportion of the total biomass constituted by
 *Aerva* * insects_%m: proportion of the total biomass constituted by
 insects * dact_%c: proportion of the total consumed carbon constituted by
 *Dactyloctenium* * euph_%c: proportion of the total consumed carbon
 constituted by *Euphorbia* * helio_%c: proportion of the total consumed
 carbon constituted by *Heliotropium* * aerva_%c: proportion of the total
 consumed carbon constituted by *Aerva* * insects_%c: proportion of the
 total consumed carbon constituted by insects * dact_%n: proportion of the
 total consumed nitrogen constituted by *Dactyloctenium* * euph_%n:
 proportion of the total consumed nitrogen constituted by *Euphorbia* *
 helio_%n: proportion of the total consumed nitrogen constituted by
 *Heliotropium* * aerva_%n: proportion of the total consumed nitrogen
 constituted by *Aerva* * insects_%n: proportion of the total consumed
 nitrogen constituted by insects **Description of data and file structure
 (Sheet5):** This datasheet contains data on the elemental composition of
 *S. hardwickii* diets across seasons. **Variables** * plot: plot IDs for
 all the plots marked for sampling across seasons * season: four sampling
 seasons - April, June, August, and October * intake_cn: C: N ratio of
 total daily dietary intake * total_c: total daily consumption of carbon in
 grams * total_n: total daily consumption of nitrogen in grams *
 total_mass: total biomass consumed per day in grams * prop_c: proportion
 of the dietary mass constituted by carbon * prop_n: proportion of the
 dietary mass constituted by nitrogen **Description of data and file
 structure (Sheet6):** This datasheet contains data on the elemental
 composition of *S. hardwickii* faecal matter across seasons. **Variables**
 * plot: plot IDs for all the plots marked for sampling across seasons *
 season: four sampling seasons - April, June, August, and October *
 faecal_cn: C: N ratio of the faecal matter collected from each plot *
 faecal_c%: proportion of the faecal matter constituted by carbon *
 faecal_n%: proportion of the faecal matter constituted by nitrogen