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Birthing asynchrony is not a consequence of asynchronous offspring development in a non-avian vertebrate, the Australian skink Egernia whitii


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While, GM, Jones, SM and Wapstra, E 2007 , 'Birthing asynchrony is not a consequence of asynchronous offspring development in a non-avian vertebrate, the Australian skink Egernia whitii' , Functional Ecology, vol. 21, no. 3 , pp. 513-519 , doi: 10.1111/j.1365-2435.2007.01272.x.

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1. One of the major impediments to our understanding of avian hatching asynchrony
is the difficulty in separating hypotheses that concentrate on the onset of incubation
from those that explain hatching asynchrony adaptively. To address this, ideally we
need a system(s) in which we can uncouple these two sets of hypotheses. Such a system
exists in the skink genus Egernia.
2. We documented birthing asynchrony (analogous to hatching asynchrony) and
the mechanisms underlying birthing asynchrony in the White’s skink,
Egernia whitii (Lacépède, 1804), a medium-sized, viviparous skink species that displays complex
3. Egernia whitii females gave birth to offspring asynchronously (100% of litters), with
an average of >2 days between births. We show that embryo gestation is synchronous
with asynchrony first observed at birth. Furthermore, when birth of the entire litter was
induced at the birth of the first offspring, there was no difference in development, mass
or weight between first (naturally) born offspring and second and third (induced)
4. These results suggest that birthing asynchrony in this species is not a consequence
of the constraint of asynchronous offspring development, but rather, females retain
offspring despite all offspring being fully developed. This suggests that birthing
asynchrony in this genus may have an adaptive explanation.
5. We discuss the potential adaptive explanations of birthing asynchrony in this genus,
taking into account the potential links with indirect parental care and social organization,
specifically the advantages that birthing asynchrony may offer to offspring in a highly
competitive social environment.

Item Type: Article
Authors/Creators:While, GM and Jones, SM and Wapstra, E
Keywords: hatching asynchrony, reptile, sociality, viviparity, White’s skink
Journal or Publication Title: Functional Ecology
ISSN: 0269-8463
DOI / ID Number: 10.1111/j.1365-2435.2007.01272.x
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