DOI: 10.5061/dryad.np5hqc038
title: Data from: An immune challenge induces a decline in parental effort and compensation by the mate

description: Immune defense is fundamental to diminish the negative effects of the
 attack of infectious agents, yet the activation of the immune system
 entails costs and may compromise other life history-traits such as
 reproduction. In reproductive brown booby pairs (Sula leucogaster), we
 experimentally imposed an immune challenge during incubation, by
 intraperitoneally injecting Escherichia coli lipopolysaccharide (LPS), in
 either the male or the female. We aimed to test whether activation of the
 immune response results on: (1) an increase in oxidative stress
 parameters, (2) a decline in post-hatching parental care in the treated
 individual, and (3) a compensation of the post-hatching parental effort by
 the non-treated mate. We found that activation of the immune response
 during incubation did not increase oxidative damage to lipids or total
 antioxidant capacity. However, mounting an immune response compromised
 parental effort during the chick rearing period: compared to controls,
 LPS-treated parents showed roughly a twofold decline in the rate of
 offspring feeding and preening. Interestingly, mates of LPS-treated
 parents increased 58% their feeding rate suggesting parental care
 compensation. According to a scenario of full compensation, the decline in
 parental effort of LPS-treated parents did not result in a poorer
 offspring growth or immune response, or increased levels of oxidative
 stress parameters. These findings suggest that in a long-lived species
 with long-lasting biparental care, an immune challenge compromises
 parental care, favoring parental compensation as a strategy to mitigate
 costs in terms of offspring success.
description: <strong>Summary of Methods</strong>
 The study was conducted in the brown booby breeding colony at
 Isla Larga, Parque Nacional Islas Marietas, Nayarit, México.
 Please note that "N/A" in the database indicates a
 value is not available. <strong>Experimental
 immune challenge</strong> During incubation, 61
 breeding pairs were captured and individually marked with a leg band. We
 randomly assigned pairs to the LPS group (n=41) or the control group
 (n=20). In the LPS group, one member of each pair (i.e. LPS-treated
 parent, females in 20 pairs and males in 21 pairs) was intraperitoneally
 injected with 0.10 mg of <em>E. coli </em>LPS (serotype
 O55:B5, Sigma Aldrich, catalogue L2637, St. Louis, MO, USA) dissolved in 1
 ml of Phosphate Buffered Saline solution (PBS; Sigma Aldrich, catalogue
 P4417, St. Louis, MO, USA). In the control group, one member of each pair
 was sham-treated (i.e. control-treated parent, females in ten pairs and
 males in ten pairs) with an intraperitoneal injection of 1 ml of PBS. Ten
 days later, we applied a second LPS injection to the LPS-treated parents
 to activate a secondary humoral immune response and a second PBS injection
 to control-treated parents. LPS injections were administered on average 28
 ± 12 and 18 ± 12 days before hatching for the first and the second dose,
 respectively. LPS is a conserved pathogen-associated molecular pattern
 (PAMP) with a highly immunogenic component of Gram-negative bacteria cell
 walls that mimics a bacterial infection and has been widely used in
 ecoimmunological studies. To determine oxidative stress
 parameters, we collected three 1.5 ml blood samples from the brachial vein
 of LPS- and control-treated parents: (1) before the first immune challenge
 (during the first capture), (2) ten days (± 2 days) after the first
 challenge, before the second immune challenge (second capture), and (3)
 seven days (± 2 days) after the second immune challenge (third capture).
 Immediately after collection, blood samples were kept on ice, plasma and
 blood cells were separated by centrifuged at 10000 g × 10 min, and plasma
 was stored at -80 ºC until laboratory analyses were performed. To
 determine the hatching date, the nests were checked daily between 14:00
 and 16:00 hrs. This time period was chosen as it is the time of less
 activity, to avoid disturbing the colony. Bird handling took less than 12
 min to minimize stress. <strong>Offspring growth
 and immune response</strong> In the offspring, we
 measured the increase of body mass (± 10 g), tarsus, ulna, and beak length
 (± 0.1 mm) every 5 days from hatching until 30 days post-hatching. For
 oxidative stress analyses, we collected one 1 ml blood sample from
 15-days-old offspring. As an estimate of the immune response of chicks, we
 used the phytohemagglutinin skin test that includes both, adaptive and
 innate components of the immune system. At the age of 30 days, offspring
 were injected subcutaneously in the left wing-web with 0.1 ml of 1 mg
 ml<sup>-1</sup> PHA-P (Sigma Aldrich, catalogue L9016, St.
 Louis, MO, USA) dissolved in PBS. The point of injection was marked with
 an indelible marker and wing-web thickness was measured (three times to
 yield an average) before injection and 24 hours later with a Mitutoyo
 micrometer (± 0.001 mm). We estimated the immune response to PHA as the
 wing-web swelling 24 hours after the injection. The repeatability of
 swelling measures was high (intraclass correlation coefficient ± SE:
 before injection, <em>r </em>=0.96 ± 0.008, <em>P
 </em>&lt; 0.001; after injection <em>r </em>= 0.99 ±
 0.001, <em>P </em>&lt;0.001).
 <strong>Behavioral observations</strong>
 Observations of parental care started when the chicks were
 roughly 4 days old and lasted until the chicks reached an age of 30 days.
 Nests were observed every five days (± 3 days), from 7:00 - 9:30 hours and
 18:30 - 21:00 hours, the periods of greater diurnal parental activity at
 the colony. Behavioral records were conducted by seven observers from
 roughly 3 - 6 m of distance from the focal nests. Observers were blind
 about which experimental treatment focal nests belonged. All nests
 recorded had only one chick after the second observation. Parental
 behaviors recorded were: (1) time that each parent spends near the chick
 (hereafter offspring attendance; recorded as the minute and hour a parent
 arrived and left the nest), (2) absolute number of feedings by each
 parent, (3) number of bouts of preening behavior from each parent to
 chick. From the focal offspring, we recorded (4) the number of begging
 bouts (when the chick raises the head and vocalizes with a “tac-tac”
 sound; a new begging bout was considered after a period of &gt;10
 seconds of no begging). We pooled all observations from each nest and
 calculated the time each parent spent with the offspring, and the rate per
 hour of each parental behavior (preening rate = absolute number of
 preenings by each parent / total time the nest was observed; feeding rate
 = absolute number of feedings by each parent / total offspring attendance
 by the male or the female). We independently calculated begging rates for
 the mother and father (number of begging bouts to the male or the female /
 total offspring attendance by the male or the female). We started
 behavioral recordings after a period of observers training, when
 inter-observer reliability was high (<em>r </em>= 0.97± 0.02,
 <em>P </em>= 0.02).
description: # An immune challenge induces a decline in parental effort and
 compensation by the mate
 [https://doi.org/10.5061/dryad.np5hqc038](https://doi.org/10.5061/dryad.np5hqc038) ## Description of the data and file structure The study was conducted in the brown booby breeding colony at Isla Larga, Parque Nacional Islas Marietas, Nayarit, México.  Please note that "N/A" in database file indicates a value not available. #### File: Bdd\_Martinez\_Flores2024.xlsx | **Variable** | **Description** | | :---------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------ | | Nest | Nest number | | Parent | If parent was treated (LPS or Control) or not treated (mate) | | Sex | Sex of parent (male/female) | | Treatment | LPS or Control | | 1Oxidative\_damage\_lipids | Estimate of oxidative damage to lipids (ln MDA) at first capture | | 2Oxidative\_damage\_lipids | Estimate of oxidative damage to lipids (ln MDA) at second capture | | 3Oxidative\_damage\_lipids | Estimate of oxidative damage to lipids (ln MDA) at third capture | | 1Total\_antioxidant\_capacity | Estimates of total antioxidant capacity (Trolox) at first capture | | 2Total\_antioxidant\_capacity | Estimates of total antioxidant capacity (Trolox) at second capture | | 3Total\_antioxidant\_capacity | Estimates of total antioxidant capacity (Trolox) at third capture | | Time\_in\_nest | Time that each parent (h) spent in the nest | | Preening\_chick\_h | Preening rate (h) of parents to chicks | | Feeding\_h | Feeding rate (h) of each parent to chicks | | Begging\_h | Begging rate (h) of each parent to chicks | | PairBeggingDifference | Difference in begging rate to the mate and the treated parent | | PairFeedingDifferences | Difference in feeding rate by the mate and the treated parent | | Total\_pair\_begging | Total begging rate to both parents (h) | | Total\_pair\_feeding | Total feeding rate to both parents (h) | | ChickOxiDamageLipids | Estimate of oxidative damage to lipids (ln MDA) of chicks | | ChickTotal antioxidants | Estimates of total antioxidant capacity (Trolox) of chicks | | Chick\_growth | The first PC, from a Principal Component Analysis that included the daily rates of increase of mass, beak, and ulna from ages 1 to 30 days. | | ChickPHA\_response | Inflammatory response (mm) after 24 hrs to an immune challenge with PHA |