DOI: 10.5061/dryad.mr5c0vs
title: Data from: Immune challenge induces terminal investment at an early breeding stage in female zebra finches

description: The ‘terminal investment’ hypothesis proposes that individuals with low
 future survival prospects will gain from increasing investment in the
 current reproductive event even though it will reduce the chances of
 future reproduction even further. Such investments have previously been
 found to occur mainly during the late stages of the breeding event, i.e.,
 encompassing a short period of elevated parental care close to offspring
 independence. Our aim was to study if a simulated mild bacterial infection
 can induce a terminal investment already at egg laying (i.e., at an early
 breeding stage). Therefore, we challenged female zebra finches
 (Taeniopygia guttata) prior to egg laying with a tetanus-toxoid vaccine
 mimicking a bacterial infection. Immune-challenged females increased the
 total clutch mass by 20 %, primarily through laying clutches that were 17
 % larger than control females. Although the immune-challenged females
 produced more eggs, they kept the same investment strategy in relation to
 egg laying order as did control females. Our study implies that female
 birds can use a non-pathogenic immune challenge as an indication of
 declining survival prospects, and consequently increase clutch size. These
 investment decisions by immune-challenged mothers are in line with
 ‘terminal investment’ conducted at an early stage of breeding, challenging
 the traditional view that terminal investment should occur at late
 breeding stages.
description: all
 birdsThis file includes all
 the females that got two injections and was offered a nesting
 opportunity.ID = Identity of the bird Treatment = Injection with either
 phosphate buffered saline (PBS) or tetanus-toxoid vaccine Tarsus length =
 Tarsus length (mm) of the female Body mass = Body mass (g) of the female
 Scaled index = Condition index of the femaleexp
 birdsThis file only includes
 those females that started to produce a clutch. ID = Identity of the bird
 Treatment = Injection with either phosphate buffered saline (PBS) or
 tetanus-toxoid vaccine Exp = Control females (1); tetanus-injected females
 (2) Body mass = Body mass (g) of the female Days to first egg = The time
 period between first presented with a nest box and nesting material and
 the production of the first egg by the females. Number of eggs = Clutch
 size Mean egg mass = Mean egg mass (g) of the eggs in each clutch Total
 egg mass = Total mass (g) of all eggs in a clutch Mean yolk mass = Mean
 yolk mass (g) of the eggs in each clutch Mean yolk proportion = Mean
 proportion of yolk in relation to egg mass in each clutch Arcsin mean yolk
 prop. = Arcsine transformed mean yolk proportion Diff body Mass = Initial
 body mass taken on the day of the second injection minus body mass after
 completion of egg laying. Days btw bm measurements = Number of days
 between the two body mass measurements Scaled index = Condition index of
 the female Age = Age of the female; 1 = One year old; 2 = Two years old
 Tetanus = Tetanus antibody concentrations (mODmin-1) Log (tet) = The
 logarithm of tetanus antibody concentrationseggsThis file contains all
 individual eggs Female = Female identity Treatment = Injection with either
 phosphate buffered saline (PBS) or tetanus-toxoid vaccine Exp = Control
 females (1); tetanus-injected females (2) Body mass = Body mass (g) of the
 female Clutch size = Number of eggs in the clutch Egg day = Number of days
 after the production of the first egg (egg day = 1) that each egg in the
 clutch were produced. Egg order = The order in which the eggs were
 produced Rel egg order = The egg order divided by clutch size to adjust
 egg order for variation in clutch size. Yolk mass = The yolk mass of each
 individual egg Egg mass = The total mass of each individual egg Albumen
 mass = The albumen mass of each individual egg Yolk Proportion = The
 proportion of yolk in relation to egg mass of each individual egg Yolk
 prop. arcsin = Arcsine transformed yolk proportions of each individual egg
 Scaled index = Condition index of the female