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Hechenleitner EM, Fernandez Blanco MV, Núñez-Campero SR, Fiorelli LE, Bona P. Unexpected morphological variability in the eggshells of the South American caimans Caiman latirostris and Caiman yacare. Sci Rep 2023; 13:4894. [PMID: 36966165 PMCID: PMC10039913 DOI: 10.1038/s41598-023-31837-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/17/2023] [Indexed: 03/27/2023] Open
Abstract
Eggshell morphology is a valuable indicator of the local conditions within the nests of modern crocodilians and birds. In contrast to these latter, the anatomical structure of the eggshells of most crocodilian species is practically unknown. Here, we provide the first characterization of crocodilian eggshells, using x-ray micro-CT scans. We studied eggshells of Caiman latirostris and Caiman yacare from various developmental stages that coincide with the beginning of embryonic ossification. The new 3D renderings revealed complex ornamentation, unique among crocodilians, and amphora-shaped pore canals, some of which converge in single pore openings. We also documented a high density of pore canals with a gas diffusion capacity 45 times higher than the average predicted for modern avian eggshells. The external ornamentation and the thickness of the compact layer of the eggshells (i.e. excluding ornamentation) showed ontogenetic and interspecific differences that could be related to nesting materials and nesting areas selected by each species. The shell features described here evidence a greater structural complexity than previously recognized in phylogenetically close, sympatric crocodilian species. Further comprehensive morphological analyses on other modern and fossil crocodilian eggshells using micro-CT technology will shed new light on the evolution of reproductive strategies in this intriguing archosaur clade.
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Affiliation(s)
- E Martín Hechenleitner
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB, CABA, Argentina.
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR), Provincia de La Rioja, UNLaR, SEGEMAR, UNCa, CONICET, Entre Ríos y Mendoza S/N, 5301, Anillaco, La Rioja, Argentina.
- Instituto de Biología de La Conservación y Paleobiología (IBICOPA) DACEFyN-UNLaR, Av. Gob. Vernet y Apóstol Felipe, 5300, La Rioja, Argentina.
| | - María V Fernandez Blanco
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB, CABA, Argentina.
- División Paleontología Vertebrados, Anexo II Laboratorios del Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Calles 122 y 60, B1900FWA, La Plata, Buenos Aires, Argentina.
| | - Segundo R Núñez-Campero
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB, CABA, Argentina
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR), Provincia de La Rioja, UNLaR, SEGEMAR, UNCa, CONICET, Entre Ríos y Mendoza S/N, 5301, Anillaco, La Rioja, Argentina
- Instituto de Biología de La Conservación y Paleobiología (IBICOPA) DACEFyN-UNLaR, Av. Gob. Vernet y Apóstol Felipe, 5300, La Rioja, Argentina
| | - Lucas E Fiorelli
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB, CABA, Argentina
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR), Provincia de La Rioja, UNLaR, SEGEMAR, UNCa, CONICET, Entre Ríos y Mendoza S/N, 5301, Anillaco, La Rioja, Argentina
| | - Paula Bona
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB, CABA, Argentina
- División Paleontología Vertebrados, Anexo II Laboratorios del Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Calles 122 y 60, B1900FWA, La Plata, Buenos Aires, Argentina
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Piazza MV, Fernández MS, Leiva PML, Piña CI, Simoncini MS. "Intracascaral space" an eggshell structure of Caiman latirostris eggs. Sci Rep 2021; 11:5579. [PMID: 33692431 PMCID: PMC7970913 DOI: 10.1038/s41598-021-85113-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/25/2021] [Indexed: 11/09/2022] Open
Abstract
In recent decades, eggshells of eggs from large-bodied reptiles have been studied by many researchers, to describe the eggshell, to compare them to extinct lineages that once inhabited our planet and also to understand how the egg provides the embryo specific conditions during incubation. In previous studies we described and characterized normal and pathologic Caiman latirostris eggshells; we also evaluated how the eggshell changes during incubation. In a study relating temperature variation and eggshell structures of successful eggs, we observed empty structures not previously described that we termed “intracascaral space”. The aim of this study is to describe this structure of C. latirostris eggshells. We hypothesize about the possible functions which it would perform during incubation and for development of the embryos.
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Affiliation(s)
- Mila V Piazza
- Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Campo Experimental Villarino C.C. 14, Zavalla, Santa Fe, Argentina
| | - Mariela S Fernández
- Instituto de Investigaciones en Biodiversidad y Medioambiente-Consejo Nacional de Investigaciones Científicas y Técnicas, Quintral 1250, 8300, Bariloche, Río Negro, Argentina.
| | - Pamela M L Leiva
- Centro de Investigación Científica y de Transferencia Tecnológica a la Producción-Consejo Nacional de Investigaciones Científicas y Técnicas, España 149, 3105, Diamante, Entre Ríos, Argentina.,Proyecto Yacaré, Laboratorio de Zoología Aplicada: Anexo Vertebrados (Facultad de Humanidades y Ciencias - Universidad de Nacional del Litoral / Ministerio de Aguas, Servicios Públicos y Medio Ambiente), Aristóbulo del Valle 8700, 3000, Santa Fe, Santa Fe, Argentina.,Facultad de Ciencia y Tecnología, Universidad Autónoma de Entre Ríos, Tratado del Pilar 314, 3105, Diamante, Entre Ríos, Argentina
| | - Carlos I Piña
- Centro de Investigación Científica y de Transferencia Tecnológica a la Producción-Consejo Nacional de Investigaciones Científicas y Técnicas, España 149, 3105, Diamante, Entre Ríos, Argentina.,Proyecto Yacaré, Laboratorio de Zoología Aplicada: Anexo Vertebrados (Facultad de Humanidades y Ciencias - Universidad de Nacional del Litoral / Ministerio de Aguas, Servicios Públicos y Medio Ambiente), Aristóbulo del Valle 8700, 3000, Santa Fe, Santa Fe, Argentina.,Facultad de Ciencia y Tecnología, Universidad Autónoma de Entre Ríos, Tratado del Pilar 314, 3105, Diamante, Entre Ríos, Argentina
| | - Melina S Simoncini
- Centro de Investigación Científica y de Transferencia Tecnológica a la Producción-Consejo Nacional de Investigaciones Científicas y Técnicas, España 149, 3105, Diamante, Entre Ríos, Argentina. .,Proyecto Yacaré, Laboratorio de Zoología Aplicada: Anexo Vertebrados (Facultad de Humanidades y Ciencias - Universidad de Nacional del Litoral / Ministerio de Aguas, Servicios Públicos y Medio Ambiente), Aristóbulo del Valle 8700, 3000, Santa Fe, Santa Fe, Argentina. .,Facultad de Ciencia y Tecnología, Universidad Autónoma de Entre Ríos, Tratado del Pilar 314, 3105, Diamante, Entre Ríos, Argentina.
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Cedillo-Leal C, Simoncini MS, Leiva PML, Larriera A, Lang JW, Piña CI. Eggshell structure in Caiman latirostris eggs improves embryo survival during nest inundation. Proc Biol Sci 2018; 284:rspb.2016.2675. [PMID: 28469027 DOI: 10.1098/rspb.2016.2675] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 04/05/2017] [Indexed: 11/12/2022] Open
Abstract
Egg inundation often results in poor hatching success in crocodylians. However, how tolerant eggs are to submergence, and/or how eggshell ultrastructure may affect embryo survival when inundated, are not well understood. In this study, our objective was to determine if embryo survival in Caiman latirostris is affected by eggshell surface roughness, when eggs are submerged under water. Tolerance to inundation was tested early (day 30) versus late (day 60) in development, using eight clutches (four per time treatments), subdivided into four groups: (N = 9 per clutch per treatment; 9 × 4 = 36 eggs per group). 'Rough' eggshell represented the natural, unmodified eggshell surface structure. 'Smooth' eggshell surface structure was created by mechanically sanding the natural rough surface to remove surface columnar elements and secondary layer features, e.g. irregularities that result in 'roughness'. When inundated by submerging eggs under water for 10 h at day 30, 'smooth' eggshell structure resulted in more than twice as many dead embryos (16 versus 6, smooth versus rough; N = 36), and fewer than half as many healthy embryos (6 versus 13, smooth versus rough, respectively; N = 36). By contrast, at day 60, inundation resulted in very low hatching success, regardless of eggshell surface structure. Only two hatchlings survived the inundation, notably in the untreated group with intact, rough eggshells. Inundation produced a high rate of malformations (58% at day 30), but did not affect hatchling size. Our results indicate that eggshell roughness enhances embryo survival when eggs are inundated early in development, but not late in development. Apparently, the natural surface 'roughness' entraps air bubbles at the eggshell surface during inundation, thereby facilitating gas exchange through the eggshell even when the egg is submerged under water.
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Affiliation(s)
- César Cedillo-Leal
- Instituto de Ecología Aplicada, Universidad Autónoma de Tamaulipas, Ciudad Victoria, Mexico
| | - Melina S Simoncini
- Proyecto Yacaré-Laboratorio de Zoología Aplicada: Anexo Vertebrados (FHUC-UNL/MASPyMA), Santa Fe, Argentina .,CICyTTP-UADER-Prov Entre Ríos-CONICET. FCyT, Dr Materi y España, Diamante, Argentina
| | - Pamela M L Leiva
- Proyecto Yacaré-Laboratorio de Zoología Aplicada: Anexo Vertebrados (FHUC-UNL/MASPyMA), Santa Fe, Argentina.,CICyTTP-UADER-Prov Entre Ríos-CONICET. FCyT, Dr Materi y España, Diamante, Argentina
| | - Alejandro Larriera
- Proyecto Yacaré-Laboratorio de Zoología Aplicada: Anexo Vertebrados (FHUC-UNL/MASPyMA), Santa Fe, Argentina
| | - Jeffrey W Lang
- Conservation Biology Program, University of Minnesota, St Paul, MN 55108, Minnesota, USA
| | - Carlos I Piña
- Proyecto Yacaré-Laboratorio de Zoología Aplicada: Anexo Vertebrados (FHUC-UNL/MASPyMA), Santa Fe, Argentina .,CICyTTP-UADER-Prov Entre Ríos-CONICET. FCyT, Dr Materi y España, Diamante, Argentina
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