DOI: 10.5061/dryad.3n5tb2rtq
title: Mate desertion affects offspring survival, development and physiology in a songbird with multiple parental strategies

description: Sexual conflict affects the amount and duration of offspring care each
 parent invests, resulting in multiple parental care strategies sometimes
 coexisting within a single population. Understanding the persistence of
 multiple parental care strategies requires a precise estimate of the
 benefits and costs associated with parental decisions. Even though the
 benefits of brood desertion are well known, the reproductive costs of
 desertion (i.e., nestlings’ physiological conditions and survival) are
 less explored. We use rock sparrows, Petronia petronia, a species in which
 both uniparental and biparental care occur in the same population, to
 investigate the costs of brood desertion. Specifically, we continuously
 monitored breeding attempts to explore the behavioral mechanisms
 (desertion decision and compensatory responses) and the reproductive and
 physiological consequences (offspring corticosterone concentrations,
 oxidative stress, telomere attrition; mechanistic) of parental care
 strategies. We show that male desertion was not related to the initial
 value of the brood (clutch size, brood size) but was associated with a
 reduction in the survival probability of the nestlings. Females caring
 alone increased their per capita feeding rate, partially compensating for
 the lack of male care. Nestlings deserted earlier also experienced higher
 oxidative stress and had higher corticosterone concentrations during the
 early stages of development, but these effects did not persist to
 fledging, and there were no differences in telomere attrition. Our
 findings indicate combined reproductive and physiological costs associated
 with brood desertion. Considering these costs is essential to
 understanding the evolution and persistence of polymorphic patterns of
 care.
description: <strong>Experimental Design</strong>:
 We conducted our study from May to July 2021 and 2022 on a wild
 rock sparrow population breeding in nest boxes on the grassland slopes of
 Valsaín (Segovia, central Spain, 40°53′74″N, 4°01′W, 1200 m above sea
 level). This population has been monitored since 2013 (Cantarero et al.
 2019; Corregidor-Castro et al. 2022). We routinely checked nest boxes for
 clutch initiation and determined the onset of egg laying, incubation, and
 hatching. After hatching (day 1), we recorded videos of all nests to
 quantify provisioning and desertion behavior on days 3, 6, 8, 11, and 14,
 for 1.5 hours each (Figure S1). Digital video cameras (Sony Handcam CX405)
 were placed approximately 20 m away from the nest boxes such that they
 would capture a ~ 2 m radius surrounding the nest box. To minimize
 observer bias, blinded methods were used when all behavioral data were
 recorded and analyzed. During each filming session, we recorded hourly
 provisioning rates (visits to the nest per hour) by the male and female,
 individually. We determined a nest to be deserted by the male when the
 male was not present during the entire duration of the video (Griggio,
 Matessi & Pilastro 2005), and did not reappear in any subsequent
 videos throughout the development period. The time of desertion was
 estimated as the midpoint between the two consecutive recordings in which
 a male was present and then not present (Griggio, Matessi &
 Pilastro 2005). During the two years of study, only male desertion was
 observed (no occurrences of female desertion). All uniparental nests in
 the present study, therefore, represent female-only care.
 <strong>Corticosterone</strong>:
 We measured offspring plasma corticosterone level using
 enzyme-linked immunosorbent assays (Enzo Life Sciences; Farmingdale, NY,
 USA) following manufacturer instructions, and read optical density on a
 plate reader at 405 nm. We first validated this assay for rock sparrows by
 using serial dilutions of plasma with two different concentrations of
 steroid displacement reagent (SDR; 0.5% and 1% of plasma volume) and a
 standard curve. From this, we determined an optimal plasma dilution of
 1:10 with 0.5% concentrated SDR for subsequent assays. The Samples order
 was randomized across plates. Intra- and inter-plate CV, calculated from
 plasma run in triplicate, were <em>17.6%</em> and
 <em>16.8%,</em> respectively.
 <strong>Oxidative Stress</strong>:
 To measure reactive oxygen metabolites (dROMs), we used a kit for
 detecting hydroperoxides (MC003, Diacron, Grosseto, Italy), which signal
 both protein and lipid oxidative damage (Consantini and Dell’Omo, 2006).
 Briefly, we diluted 2µl of blood plasma in the provided acidic buffered
 solution (1:50) and followed the end-point mode protocol from the
 manufacturer (with modifications for use on 96-well microplate) and read
 optical density on a plate reader at 546nm. Samples were run in duplicate,
 and intra- and inter-assay variation was <em>4.8%</em> and
 <em>15.9%</em>, respectively. To measure antioxidant capacity
 (oxy), we used an OXY-adsorbent test (MC 435; Diacron, Grosseto, Italy),
 which measures blood antioxidant barrier by quantifying the oxidant action
 of hypochlorous acid (HClO; Vassalle et, 2008). Briefly, we diluted 2µl of
 blood plasma in distilled water (1:100) and followed the
 manufacturer's protocol (with modifications for use on a 96-well
 microplate). We then mixed a 5µl subsample of diluted plasma with 195µl of
 proved HClO solution. All samples were run in triplicate, with calibrators
 distributed vertically and horizontally across the plate. Intra- and
 inter-assay variation was <em>8.1%</em>% and
 <em>5.3%</em>, respectively. A biologically
 relevant assessment of oxidative stress includes both the levels of
 circulating dROMs and the absorbance capacity of the blood (Oxy) within
 individuals. So, we used an integrative index of oxidative stress to
 combine these measures (Vassalle et al. 2008). We standardized dROM and
 oxy using the function ‘scale’ and then calculated the difference between
 scaled values for each individual, such that higher values of the
 oxidative stress index correspond to a greater differential between dROM
 and oxy.
 <strong>Telomeres</strong>:
 Genomic DNA was extracted from erythrocytes using the Qiagen
 DNeasy Blood and Tissue Kit, following the manufacturer's protocol
 with a modification: the wash with buffer 2 was repeated twice. Sample
 elution from the column was also performed twice with 30 µl of AE buffer
 provided in the kit. DNA quality of each elution was assessed using a
 Nanodrop ND-2000 C spectrophotometer (Thermo Scientific, USA), with
 260/280 and 260/230 ratios greater than 1.8 considered acceptable. DNA
 quantification was performed using Qubit (Invitrogen) with the AccuGreen
 Broad Range dsDNA quantification kit (Biotium). Samples were diluted to a
 concentration of 3 ng/µl.  Relative telomere length (RTL) was measured
 using quantitative real-time PCR (qPCR) (Cawthon, 2002), calculating the
 ratio between telomeric DNA and the single-copy reference gene
 Glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Telomeric primers Tel1b
 and Tel2b, and GAPDH primers GAPDH-F and R were employed (Criscuolo et
 al., 2009). Amplifications were performed on a BioRad CFX384 Touch
 Real-Time PCR System. Each reaction was conducted in a 10 µl volume,
 containing 2 µl of 5× HOT FIREPol® EvaGreen® qPCR Mix Plus (without ROX)
 (Solis BioDyne), 6 ng of genomic DNA, and 200 nM of each forward and
 reverse primer. The qPCR profile consisted of an initial step at 95°C for
 12 minutes, followed by 40 cycles of 95°C for 20 seconds, 58°C for 18
 seconds, and 72°C for 1 minute. Upon completion of each run, a melt curve
 (65 to 95°C, with 0.5°C increments for 5 seconds) was generated to confirm
 qPCR specificity. Each plate contained samples collected from nestlings at
 8 and 14 days after hatching, two interplate calibrators, and a negative
 control for both telomere and GAPDH, all run in triplicate. Baseline and
 cycle quantification (Cq) values were corrected using LinRegPCR software
 ver. 2017.1 (Ruijter et al., 2009). Between-run variation was removed
 using Factor qPCR (Ruijter et al., 2015). Relative telomere length was
 calculated following the equation proposed by Pfaffl (Pfaffl, 2001), as
 reported in Morbiato et al. (2023) and in Monteforte et al. (2020). An
 acceptance threshold for amplification efficiency was set at 100 ± 20%.
 Interassay coefficients of variation (CV) were 3.7% for telomere and 1.3%
 for GAPDH, while intraassay CVs were 1.3% for telomere and 1.4% for
 GAPDH.
description: # Mate desertion affects offspring survival, development and physiology in
 a songbird with multiple parental strategies
 [https://doi.org/10.5061/dryad.3n5tb2rtq](https://doi.org/10.5061/dryad.3n5tb2rtq) ## Description of the data and file structure Nest and offspring level data measured from wild Rock Sparrow (*Petronia petronia*) population breeding in nest boxes on the grassland slopes of Valsaín (Segovia, central Spain). Parental care decisions (if and when desertion occurs), offspring growth and physiology, and offspring survival were recorded from hatching to fledging. All NA values represent data that are not available. ### Files and variables #### File: alldata.csv **Description:**  ##### Variables * nest_year: combined nest identifier and year of observation so that nest boxes used in multiple years by different pairs will be distinct * chickID: individual offspring identifier * age: age of offspring (days post-hatch) * cort: corticosterone levels measured in blood plasma using enzyme-linked immunoassay (pg/mL) * oxy: measurement of blood antioxidant barrier in blood plasma, quantified oxidant action of hypochlorous acid (uMol HClO/mL) * drom: hydroperoxides concentration in blood plasma (mg H2O2/dL) * Telomere: delta relative telomere length (change in telomere length within individual between day 8 and 14 of development.  * broodsize: number of live offspring in nest * tarsus: length of tarsus (mm) * weight: mass (g) * wing: length of wing (mm) * NEST: Nest ID * YEAR: Year of data collection * hatch_succ: Number of offspring successfully hatched out of number of eggs (proportion) * fledge_succ: Number of offspring successfully fledged out of number of offspring hatched (proportion) * num_c_fledged: Number of offspring successfully fledged (assumed if observed alive at day 14 of development) * Day_Deserted: Day after hatching at which male was assumed to have deserted the nest, based on the observation that the male was no longer seen provisioning offspring for the remainder of the nesting period.   * strategy: Parental care strategy as initially recorded (biparental care, uniparental care, or day of desertion if intermediate) * prop_deserted: The day male was assumed to have deserted as a proportion of the total number of days of nesting.  * CS: clutch size; number of eggs in nest at beginning of nesting period * HD: hatch date; date eggs were observed to have hatched * LD: lay date; date of eggs first observed in the nest * F_RING: female ID * strategy_trinom: Categories of parental care strategy (biparental, uniparental, or partial desertion) * NestID: Nest identifier  * year: year of data collection * Chick_Age: Age of offspring post-hatch * tot_visits: visits observed of any parent feeding at the nest within observation period  * m_visit_rate: visits observed of male feeding at the nest within observation period  * f_visit_rate: visits observed of female feeding at the nest within observation period  * obs_alt_visits: alternation score * obs_nonalt_visits: non-alternation score * obs_prop_alternation: * Alt_score: alternation score * feedrate: visits observed of any parent feeding at the nest within observation period, divided by number of offspring (proportion).  * strategy_binom: parental care strategy at each day of observation (uniparental or biparental). Nests that were deserted mid-way through the nesting period were considered biparental before desertion, and uniparental after desertion.  * mass_3: mass of offspring at day 3 (g) * mass_14: mass of offspring at day 14 (g) #### File: nests.csv **Description:**  ##### Variables * NEST: Nest identifier * YEAR: year of study * CS: clutch size; number of eggs in nest at beginning of nesting period * HD: hatch date; date eggs were observed to have hatched * LD: lay date; date of eggs first observed in the nest * BS D3: Brood size on day 3 (number of offspring observed in nest) * BS D14: Brood size on day 14 (number of offspring observed in nest) * Hatching Suc: Number of offspring successfully hatched out of number of eggs (proportion) * Fledging Suc: Number of offspring successfully fledged out of number of offspring hatched (proportion) * Parental strategy: Parental care strategy as initially recorded (biparental care, uniparental care, or day of desertion if intermediate) * Day_Deserted: Day after hatching at which male was assumed to have deserted the nest, based on the observation that the male was no longer seen provisioning offspring for the remainder of the nesting period.   * F_RING: Female identifier  * F_RING L/R: location of band * F_COLOUR L/R: color of band * F_AGE: age of female if known  * F_TARSUS: tarsus length of female (mm) * F_WEIGHT: mass of female (g)  * M_RING: Male identifier * M_RING L/R: location of band * M_COLOUR L/R: color of band * C_TARSUS: Average tarsus length of offspring in nest (mm) * C_WEIGHT: Average mass of offspring in nest (g) at hatching * C_BODCOND: Average body condition of offspring in nest at hatching * C_WING: Average wing length of offspring in nest (mm) * P1: offspring identifier * P2:  offspring identifier * P3:  offspring identifier * P4:  offspring identifier * P5:  offspring identifier * P6:  offspring identifier ## Code/software R version 4.3.2 (2023-10-31) Packages loaded: library(readr) library(readxl) library(tidyverse) library(lme4) library(betareg) library(AICcmodavg) library(rjags) library(zoib) library(coda) library(DHARMa) library(tidyverse) library(brms) library(tidybayes) library(broom) library(broom.mixed)  library(betareg) library(extraDistr) library(ggdist) library(gghalves) library(ggbeeswarm) library(ggrepel) library(patchwork) library(scales) library(marginaleffects) library(modelsummary) library(cmdstanr) library(knitr) library(car) library(ggpubr) library(survminer) library(survival) library(ggsurvfit) library(coxme) library(sjPlot) library(wesanderson)