Do birds differentially distribute antimicrobial proteins within clutches of eggs?

Shawkey, Matthew D.; Kosciuch, Karl L.; Liu, Mark; Rohwer, Frank C.; Loos, Elizabeth R.; Wang, Jennifer M.; Beissinger, Steven R.

doi:10.1093/beheco/arn019

Cited by 56 publications

(88 citation statements)

References 50 publications

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“…For example, Kowalczyk et al (1985) estimated that egg IgYs would reflect 10-20% of the female IgY production. However for lysozyme the costs are not clear and it likely does not derive from maternal circulation, as IgYs (see discussion in, for example, Shawkey et al, 2008). Lysozyme levels correlate with, for example, hatching success (Saino et al, 2002), but experimental evidence for their fitness effects is lacking, and more research is thus needed to understand their potential for being under selection.…”

Section: Discussionmentioning

confidence: 99%

Heritable variation in maternally derived yolk androgens, thyroid hormones and immune factors

et al. 2016

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Maternal reproductive investment can critically influence offspring phenotype, and thus these maternal effects are expected to be under strong natural selection. Knowledge on the extent of heritable variation in the physiological mechanisms underlying maternal effects is however limited. In birds, resource allocation to eggs is a key mechanism for mothers to affect their offspring and different components of the egg may or may not be independently adjusted. We studied the heritability of egg components and their genetic and phenotypic covariation in great tits (Parus major), using captive-bred full siblings of wild origin. Egg mass, testosterone (T) and androstenedione (A4) hormone concentrations showed moderate heritability, in agreement with earlier findings. Interestingly, yolk triiodothyronine hormone (T3), but not its precursor, thyroxine hormone (T4), concentration was heritable. An immune factor, albumen lysozyme, showed moderate heritability, but yolk immunoglobulins (IgY) did not. The genetic correlation estimates were moderate but statistically nonsignificant; a trend for a positive genetic correlation was found between A4 and egg mass, T and lysozyme and IgY and lysozyme, respectively. Interestingly, phenotypic correlations were found only between A4 and T, and T4 and T3, respectively. Given that these egg components are associated with fitness-related traits in the offspring (and mother), and that we show that some components are heritable, it opens the possibility that natural selection may shape the rate and direction of phenotypic change via egg composition.

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Section: Discussionmentioning

confidence: 99%

Heritable variation in maternally derived yolk androgens, thyroid hormones and immune factors

et al. 2016

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“…A few studies have quantified antimicrobial proteins in eggs of birds in the wild and have reported a wide range of lysozyme concentrations, e.g. 0.65±0.76 μg ml −1 in blue tits (D'Alba et al, 2010b) compared with 5.91 mg ml −1 in the green-rumped parrotlet (Forpus passerinus) (Shawkey et al, 2008). It has been hypothesized that concentration of antimicrobial proteins in the eggs should increase with the risk of egg infection (Shawkey et al, 2008;D'Alba et al, 2010b).…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial properties of a nanostructured eggshell from a compost-nesting bird

D’Alba

Jones

Badawy

et al. 2013

Journal of Experimental Biology

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Infection is an important source of mortality for avian embryos but parental behaviors and eggs themselves can provide a network of antimicrobial defenses. Mound builders (Aves: Megapodiidae) are unique among birds in that they produce heat for developing embryos not by sitting on eggs but by burying them in carefully tended mounds of soil and microbially decomposing vegetation. The low infection rate of eggs of one species in particular, the Australian brush-turkey (Alectura lathami), suggests that they possess strong defensive mechanisms. To identify some of these mechanisms, we first quantified antimicrobial albumen proteins and characterized eggshell structure, finding that albumen was not unusually antimicrobial, but that eggshell cuticle was composed of nanometer-sized calcite spheres. Experimental tests revealed that these modified eggshells were significantly more hydrophobic and better at preventing bacterial attachment and penetration into the egg contents than chicken eggs. Our results suggest that these mechanisms may contribute to the antimicrobial defense system of these eggs, and may provide inspiration for new biomimetic anti-fouling surfaces.

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“…Here, our results constitute, to our knowledge, the first experimental demonstration of a differential allocation of lysozyme into albumen according to paternal coloration. Shawkey et al [56] proposed recently that a trade-off between egg and blood immunity may not exist concerning this enzyme for two reasons: (i) egg and adult lysozyme are produced by different, specialized cells [57 -59], and (ii) production and deposition of antimicrobials may be less costly than deposition of other yolk factors, such as carotenoids, antibodies and hormones (calculations from Tristam [60]). However, our data show that the deposition of this antibiotic in albumen is probably beneficial enough in some aspect(s) that females differentially allocate it according to the perceived value of one's mate and the associated reproductive bout.…”

Section: Discussionmentioning

confidence: 99%

Maternal investment of female mallards is influenced by male carotenoid-based coloration

et al. 2010

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The differential allocation hypothesis predicts that females modify their investment in a breeding attempt according to its reproductive value. One prediction of this hypothesis is that females will increase reproductive investment when mated to high-quality males. In birds, it was shown that females can modulate pre-hatch reproductive investment by manipulating egg and clutch sizes and/or the concentrations of egg internal compounds according to paternal attractiveness. However, the differential allocation of immune factors has seldom been considered, particularly with an experimental approach. The carotenoid-based ornaments can function as reliable signals of quality, indicating better immunity or ability to resist parasites. Thus, numerous studies show that females use the expression of carotenoid-based colour when choosing mates; but the influence of this paternal coloration on maternal investment decisions has seldom been considered and has only been experimentally studied with artificial manipulation of male coloration. Here, we used dietary carotenoid provisioning to manipulate male mallard (Anas platyrhynchos) bill coloration, a sexually selected trait, and followed female investment. We show that an increase of male bill coloration positively influenced egg mass and albumen lysozyme concentration. By contrast, yolk carotenoid concentration was not affected by paternal ornamentation. Maternal decisions highlighted in this study may influence chick survival and compel males to maintain carotenoid-based coloration from the mate-choice period until egg-laying has been finished.

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Do birds differentially distribute antimicrobial proteins within clutches of eggs?

Cited by 56 publications

References 50 publications

Heritable variation in maternally derived yolk androgens, thyroid hormones and immune factors

Heritable variation in maternally derived yolk androgens, thyroid hormones and immune factors

Antimicrobial properties of a nanostructured eggshell from a compost-nesting bird

Maternal investment of female mallards is influenced by male carotenoid-based coloration

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