Abstract
The fact that avian eggs contain antibody of maternal origin is well documented, but only recently has this
phenomenon been considered in an ecological context. We used tree swallows (Tachycineta bicolor) to examine the
possibility of transgenerational immunity and its effect on nestling growth and immune development. We measured
cell-mediated immunity with a delayed-hypersensitivity assay and antibody-mediated immunity with a hemagglutination
test with sheep red blood cells (SRBCs). We tested for differences in immunocompetence and growth between nestlings
from females who had been exposed to a novel antigen prior to egg laying and nestlings from unexposed females. To
determine whether the effect, if any, resulted from something transferred to the eggs prior to egg laying or from subsequent
changes in parental behaviour, nestlings were exchanged so that at each nest half the nestlings were from females
who had been injected with SRBCs and half were from females who had not been exposed to SRBCs. Finally,
brood sizes were independently manipulated to either 4 or 6 nestlings. We failed to detect maternal antibodies in any
nestlings, and whether a female was exposed to SRBCs or not had no effect on the growth or cell-mediated immunity
of her brood. However, nestlings in smaller broods grew better than nestlings in larger broods, though we did not find
the expected differences in cell-mediated immunity. Furthermore, within each nest, nestlings whose mothers had been
exposed to SRBCs grew better than nestlings whose mothers had not been exposed. These results are contrary to the
idea of a simple trade-off in the allocation of resources between parasite protection and reproduction; however, they
support the idea that exposure of females to parasites prior to egg laying leads to better nestling growth, and are congruous
with the possibility of mithridatic parental care.
Original language | English |
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Pages (from-to) | 918-925 |
Journal | Canadian Journal of Zoology |
Volume | 80 |
Issue number | 5 |
DOIs | |
Publication status | Published - 2002 |
Keywords
- reproductive effort
- immunocompetence handicap
- testosterone
- antibodies
- blackbird
- sparrows
- survival
- defense
- weight
- birds