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Myth busting? Effects of embryo positioning and egg turning on hatching success in the water snake Natrix maura.

Aubret F, Blanvillain G, Kok PJ - Sci Rep (2015)

Bottom Line: Here, we used 338 eggs from 32 clutches of the water snake Natrix maura to (1) thoroughly describe natural clutch arrangement, (2) experimentally assess the effects of natural embryo positioning and (3) egg turning on embryo metabolism, hatching success, and hatchling phenotype.Egg turning did not significantly influence egg development, hatching success or hatchling phenotypes.However, post-birth mortality was significantly higher in turned (37.5%) compared to unturned (4.5%) embryos, providing support to the common belief that eggs should not be moved from their natural position.

View Article: PubMed Central - PubMed

Affiliation: Station d'Ecologie Expérimentale de Moulis, CNRS, 09200 Moulis, France.

ABSTRACT
It is a common belief that reptile eggs should not be turned after oviposition once the embryo has attached itself to the inner membrane of the shell as it might kill developing embryos. Here, we used 338 eggs from 32 clutches of the water snake Natrix maura to (1) thoroughly describe natural clutch arrangement, (2) experimentally assess the effects of natural embryo positioning and (3) egg turning on embryo metabolism, hatching success, and hatchling phenotype. Clutches contained, on average, 59% of embryos located at the top, 28% at the bottom, and 14% on a side of the egg. Larger females laid larger clutches with higher proportion of top located embryos. Top embryos displayed higher metabolic rates (heart rates), shorter incubation time, and produced lighter and shorter snakes than bottom embryos. Egg turning did not significantly influence egg development, hatching success or hatchling phenotypes. However, post-birth mortality was significantly higher in turned (37.5%) compared to unturned (4.5%) embryos, providing support to the common belief that eggs should not be moved from their natural position.

No MeSH data available.


Related in: MedlinePlus

A total of 263 eggs (N = 22 clutches) of water snake were checked for the positon of their embryos within 12 hours post-laying.The proportions of eggs with top embryos (i.e. embryos located at the top of the egg) increased as non-linear function of clutch-size. Regression line is plotted as a quadratic fit (r = 0.75; F2, 19 = 12.27; P = 0.0004; equation y = −1.7925x + 0.2385x2 + 29.3186).
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f2: A total of 263 eggs (N = 22 clutches) of water snake were checked for the positon of their embryos within 12 hours post-laying.The proportions of eggs with top embryos (i.e. embryos located at the top of the egg) increased as non-linear function of clutch-size. Regression line is plotted as a quadratic fit (r = 0.75; F2, 19 = 12.27; P = 0.0004; equation y = −1.7925x + 0.2385x2 + 29.3186).

Mentions: A multiple regression analysis with mother snout vent-length (SVL) as continuous predictor and the number of top embryos, the number of attached eggs, and clutch size as dependent variables yielded Wilks’ λ = 0.51; F3, 18 = 5.71; P = 0.006. Mother SVL significantly explained the variation in the proportion of eggs with top embryos within a clutch, as well as clutch size, but not the variation of eggs attached to each other in a clutch (Table 2). Further, the proportion of eggs with top embryos increased as a non-linear function of clutch-size (see Fig. 2).


Myth busting? Effects of embryo positioning and egg turning on hatching success in the water snake Natrix maura.

Aubret F, Blanvillain G, Kok PJ - Sci Rep (2015)

A total of 263 eggs (N = 22 clutches) of water snake were checked for the positon of their embryos within 12 hours post-laying.The proportions of eggs with top embryos (i.e. embryos located at the top of the egg) increased as non-linear function of clutch-size. Regression line is plotted as a quadratic fit (r = 0.75; F2, 19 = 12.27; P = 0.0004; equation y = −1.7925x + 0.2385x2 + 29.3186).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543940&req=5

f2: A total of 263 eggs (N = 22 clutches) of water snake were checked for the positon of their embryos within 12 hours post-laying.The proportions of eggs with top embryos (i.e. embryos located at the top of the egg) increased as non-linear function of clutch-size. Regression line is plotted as a quadratic fit (r = 0.75; F2, 19 = 12.27; P = 0.0004; equation y = −1.7925x + 0.2385x2 + 29.3186).
Mentions: A multiple regression analysis with mother snout vent-length (SVL) as continuous predictor and the number of top embryos, the number of attached eggs, and clutch size as dependent variables yielded Wilks’ λ = 0.51; F3, 18 = 5.71; P = 0.006. Mother SVL significantly explained the variation in the proportion of eggs with top embryos within a clutch, as well as clutch size, but not the variation of eggs attached to each other in a clutch (Table 2). Further, the proportion of eggs with top embryos increased as a non-linear function of clutch-size (see Fig. 2).

Bottom Line: Here, we used 338 eggs from 32 clutches of the water snake Natrix maura to (1) thoroughly describe natural clutch arrangement, (2) experimentally assess the effects of natural embryo positioning and (3) egg turning on embryo metabolism, hatching success, and hatchling phenotype.Egg turning did not significantly influence egg development, hatching success or hatchling phenotypes.However, post-birth mortality was significantly higher in turned (37.5%) compared to unturned (4.5%) embryos, providing support to the common belief that eggs should not be moved from their natural position.

View Article: PubMed Central - PubMed

Affiliation: Station d'Ecologie Expérimentale de Moulis, CNRS, 09200 Moulis, France.

ABSTRACT
It is a common belief that reptile eggs should not be turned after oviposition once the embryo has attached itself to the inner membrane of the shell as it might kill developing embryos. Here, we used 338 eggs from 32 clutches of the water snake Natrix maura to (1) thoroughly describe natural clutch arrangement, (2) experimentally assess the effects of natural embryo positioning and (3) egg turning on embryo metabolism, hatching success, and hatchling phenotype. Clutches contained, on average, 59% of embryos located at the top, 28% at the bottom, and 14% on a side of the egg. Larger females laid larger clutches with higher proportion of top located embryos. Top embryos displayed higher metabolic rates (heart rates), shorter incubation time, and produced lighter and shorter snakes than bottom embryos. Egg turning did not significantly influence egg development, hatching success or hatchling phenotypes. However, post-birth mortality was significantly higher in turned (37.5%) compared to unturned (4.5%) embryos, providing support to the common belief that eggs should not be moved from their natural position.

No MeSH data available.


Related in: MedlinePlus