Nesting environment may drive variation in eggshell structure and egg characteristics in the Testudinata

2018 ◽  
Vol 329 (6-7) ◽  
pp. 331-342 ◽  
Author(s):  
D. Charles Deeming
Keyword(s):  
Eggshell Structure ◽  
Nesting Environment

scholarly journals The formation of a hatching line in the serosal cuticle confers multifaceted adaptive functions on the eggshell of a cicada

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Minoru Moriyama ◽  
Kouji Yasuyama ◽  
Hideharu Numata
Keyword(s):  
Protective Role ◽  
Terminal Phase ◽  
Embryonic Diapause ◽  
Insect Eggs ◽  
Ridge Structure ◽  
Conflicting Demands ◽  
Partial Degradation ◽  
Egg Period ◽  
Eggshell Structure

AbstractInsect eggshells must meet various demands of developing embryos. These demands sometimes conflict with each other; therefore, there are tradeoffs between eggshell properties, such as robustness and permeability. To meet these conflicting demands, particular eggshell structures have evolved in diverse insect species. Here, we report a rare eggshell structure found in the eggshell of a cicada, Cryptotympana facialis. This species has a prolonged egg period with embryonic diapause and a trait of humidity-inducible hatching, which would impose severe demands on the eggshell. We found that in eggs of this species, unlike many other insect eggs, a dedicated cleavage site, known as a hatching line, was formed not in the chorion but in the serosal cuticle. The hatching line was composed of a fine furrow accompanied by ridges on both sides. This furrow-ridge structure formed in the terminal phase of embryogenesis through the partial degradation of an initially thick and nearly flat cuticle layer. We showed that the permeability of the eggshell was low in the diapause stage, when the cuticle was thick, and increased with degradation of the serosal cuticle. We also demonstrated that the force required to cleave the eggshell was reduced after the formation of the hatching line. These results suggest that the establishment of the hatching line on the serosal cuticle enables flexible modification of eggshell properties during embryogenesis, and we predict that it is an adaptation to maximize the protective role of the shell during the long egg period while reducing the barrier to emerging nymphs at the time of hatching.

Eggshell structure, mode of development and growth rate in birds

Zoology ◽  
2008 ◽  
Vol 111 (6) ◽  
pp. 494-502 ◽  
Author(s):  
Ola Karlsson ◽  
Clas Lilja
Keyword(s):  
Growth Rate ◽  
Mode Of Development ◽  
Eggshell Structure

Salinity of the coastal nesting environment and its association with body size in the estuarine pig-nosed turtle

2014 ◽  
Vol 295 (1) ◽  
pp. 65-74 ◽  
Author(s):  
C. C. Eisemberg ◽  
M. Rose ◽  
B. Yaru ◽  
Y. Amepou ◽  
A. Georges
Keyword(s):  
Body Size ◽  
Nesting Environment

Oviducal structure in four species of gekkonid lizard differing in parity mode and eggshell structure

1998 ◽  
Vol 10 (2) ◽  
pp. 139 ◽  
Author(s):  
J. E. Girling ◽  
A. Cree ◽  
L. J. Guillette, Jr
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Epithelial Cells ◽  
Uterine Tube ◽  
Hemidactylus Turcicus ◽  
Transmission Electron ◽  
Eggshell Structure ◽  
Scanning Electron ◽  
Parity Mode

Oviducal structure was analysed in vitellogenic females from four species of gekkonid lizard exhibiting variation in parity mode and eggshell structure: Hemidactylus turcicus (oviparous) which produces a hard, calcareous eggshell; Saltuarius wyberba (oviparous) which produces a soft, parchment-like eggshell; and Hoplodactylus maculatus and Hoplodactylus duvaucelii (both viviparous). Oviducts were analysed by light, scanning electron and transmission electron microscopy. The uterus exhibited differences among species that were directly attributable to parity mode. H. turcicus and S. wyberba (oviparous) had numerous uterine shell glands; H. maculatus and H. duvaucelii(viviparous) had very few. The uterus also exhibited differences between the two oviparous species (H. turcicusand S. wyberba) which may be related to the type of eggshell produced. Variations were noted in the staining properties of the uterine glandular and epithelial cells. The structure of the infundibulum, uterine tube, isthmus and vagina also differed among species, but differences could not be directly related to parity mode or eggshell structure. Instead, the differences may be related to how prepared the oviduct is for ovulation in individuals analysed from the different species. This study confirms, in the Gekkonidae, aspects of oviducal structure that have been associated with parity mode in other squamate taxa.

Eggshell Structure of the Predator Harpactor angulosus (Hemiptera: Reduviidae)

2012 ◽  
Vol 105 (6) ◽  
pp. 896-901 ◽  
Author(s):  
Tiago G. Pikart ◽  
Gabriely K. Souza ◽  
Terezinha V. Zanuncio ◽  
José C. Zanuncio ◽  
José E. Serrão
Keyword(s):  
Eggshell Structure

scholarly journals Biomechanical evidence suggests extensive eggshell thinning during incubation in the Sanagasta titanosaur dinosaurs

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4971 ◽  
Author(s):  
E. Martín Hechenleitner ◽  
Jeremías R. A. Taborda ◽  
Lucas E. Fiorelli ◽  
Gerald Grellet-Tinner ◽  
Segundo R. Nuñez-Campero
Keyword(s):  
Finite Element ◽  
Late Cretaceous ◽  
Shell Thickness ◽  
Parent Species ◽  
Finite Element Analyses ◽  
Morphological Variations ◽  
Eggshell Thinning ◽  
Nesting Sites ◽  
Thick Shells ◽  
Nesting Environment

The reproduction of titanosaur dinosaurs is still a complex and debated topic. Their Late Cretaceous nesting sites are distributed worldwide and their eggs display substantial morphological variations according to the parent species. In contrast to the typical 1.3–2.0 mm thick shells common to eggs of most titanosaur species (e.g., those that nested in Auca Mahuevo, Tama, Toteşti or Boseong), the Cretaceous Sanagasta eggs of Argentina display an unusual shell thickness of up to 7.9 mm. Their oviposition was synchronous with a palaeogeothermal process, leading to the hypothesis that their extra thick eggshell was an adaptation to this particular nesting environment. Although this hypothesis has already been supported indirectly through several investigations, the mechanical implications of developing such thick shells and how this might have affected the success of hatching remains untested. Finite element analyses estimate that the breaking point of the thick-shelled Sanagasta eggs is 14–45 times higher than for other smaller and equally sized titanosaur eggs. The considerable energetic disadvantage for piping through these thick eggshells suggests that their dissolution during incubation would have been paramount for a successful hatching.

Uterine and eggshell structure and histochemistry in a lizard with prolonged uterine egg retention (Lacertilia, Scincidae, Saiphos)

2010 ◽  
Vol 271 (11) ◽  
pp. 1342-1351 ◽  
Author(s):  
James R. Stewart ◽  
Ashley N. Mathieson ◽  
Tom W. Ecay ◽  
Jacquie F. Herbert ◽  
Scott L. Parker ◽  
...  
Keyword(s):  
Egg Retention ◽  
Eggshell Structure

scholarly journals Evolution of eggshell structure during rapid range expansion in a passerine bird

2011 ◽  
Vol 25 (6) ◽  
pp. 1215-1222 ◽  
Author(s):  
Laura R. Stein ◽  
Alexander V. Badyaev
Keyword(s):  
Range Expansion ◽  
Passerine Bird ◽  
Eggshell Structure
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