Sexual dimorphism in the turtle Kinosternon scorpioides (Testudines: Kinosternidae) from Marajó Island, Brazilian Amazon

Abstract Introduction: Morphometrics analysis is an efficient and low-cost technique used in studies of sexual dimorphism in turtles. Kinosternon scorpioides scorpioides, scorpion mud turtle, has a wide phenotypic variation, depending on the area of its occurrence. Objective: The objective of this work was to identify the anatomical sexual difference of K. s. scorpioides, adults and hatchlings, through morphometric analysis; and relate the weights of adult animals to environmental factors (temperature and rainfall) in Marajó Island, Brazil. Methods: The sample collection was carried out from March to September 2018, covering both the rainy season (January to July) and the dry season (August to December). For the biometric analysis, 95 adults and 21 hatchlings were used, in which the length and width of the carapace and plastron, height of the shell, and weight were measured (adults only). For the geometric morphometry analysis, 21 adults and 13 hatchlings were used, in which 27 coordinates of anatomical landmarks were inserted in each image of the carapace and 11 in the plastron. Hatchlings were sexed by histology which was enabled by the identification of the ovaries and testicles. Results: The results showed the existence of dimorphism in adults. The plastron and height were higher in females, which had a more rounded carapace than males. This characteristic may be related to the species’ sexual strategy, where males impose copulation. Histologically, it was possible to identify the ovaries and testicles in the hatchlings, but there was no anatomical sexual difference, despite the tendency to differentiate in the analysis of carapace PCA. Conclusions: Sexual dimorphism in K. s. scorpioides may play an important role on its reproductive behavior, which is synchronized with environmental events. This fact suggests that the reproductive strategies of this species would be severely affected by changes in the ecosystem.

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Main Authors: Silva-da-Silva,Joilson, dos-Santos-Braga,Brenda-Stefany, Da-Silva-Costa,Juliane, Schlemmer-Brasil,Leandro, Lobato-de-Oliveira-Bahia,Verônica-Regina, Pimentel-Leal,Relionan, Felipe-Marques,José-Ribamar, de-Araújo-Guimarães,Diva-Anélie
Format: Digital revista
Language:English
Published: Universidad de Costa Rica 2021
Online Access:http://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0034-77442021000200601
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spelling oai:scielo:S0034-774420210002006012021-08-11Sexual dimorphism in the turtle Kinosternon scorpioides (Testudines: Kinosternidae) from Marajó Island, Brazilian AmazonSilva-da-Silva,Joilsondos-Santos-Braga,Brenda-StefanyDa-Silva-Costa,JulianeSchlemmer-Brasil,LeandroLobato-de-Oliveira-Bahia,Verônica-ReginaPimentel-Leal,RelionanFelipe-Marques,José-Ribamarde-Araújo-Guimarães,Diva-Anélie biometrics geometry morphometrics scorpion mud turtle sexual difference turtles Abstract Introduction: Morphometrics analysis is an efficient and low-cost technique used in studies of sexual dimorphism in turtles. Kinosternon scorpioides scorpioides, scorpion mud turtle, has a wide phenotypic variation, depending on the area of its occurrence. Objective: The objective of this work was to identify the anatomical sexual difference of K. s. scorpioides, adults and hatchlings, through morphometric analysis; and relate the weights of adult animals to environmental factors (temperature and rainfall) in Marajó Island, Brazil. Methods: The sample collection was carried out from March to September 2018, covering both the rainy season (January to July) and the dry season (August to December). For the biometric analysis, 95 adults and 21 hatchlings were used, in which the length and width of the carapace and plastron, height of the shell, and weight were measured (adults only). For the geometric morphometry analysis, 21 adults and 13 hatchlings were used, in which 27 coordinates of anatomical landmarks were inserted in each image of the carapace and 11 in the plastron. Hatchlings were sexed by histology which was enabled by the identification of the ovaries and testicles. Results: The results showed the existence of dimorphism in adults. The plastron and height were higher in females, which had a more rounded carapace than males. This characteristic may be related to the species’ sexual strategy, where males impose copulation. Histologically, it was possible to identify the ovaries and testicles in the hatchlings, but there was no anatomical sexual difference, despite the tendency to differentiate in the analysis of carapace PCA. Conclusions: Sexual dimorphism in K. s. scorpioides may play an important role on its reproductive behavior, which is synchronized with environmental events. This fact suggests that the reproductive strategies of this species would be severely affected by changes in the ecosystem.info:eu-repo/semantics/openAccessUniversidad de Costa RicaRevista de Biología Tropical v.69 n.2 20212021-06-01info:eu-repo/semantics/articletext/htmlhttp://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0034-77442021000200601en10.15517/rbt.v69i2.42834
institution SCIELO
collection OJS
country Costa Rica
countrycode CR
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access En linea
databasecode rev-scielo-cr
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region America Central
libraryname SciELO
language English
format Digital
author Silva-da-Silva,Joilson
dos-Santos-Braga,Brenda-Stefany
Da-Silva-Costa,Juliane
Schlemmer-Brasil,Leandro
Lobato-de-Oliveira-Bahia,Verônica-Regina
Pimentel-Leal,Relionan
Felipe-Marques,José-Ribamar
de-Araújo-Guimarães,Diva-Anélie
spellingShingle Silva-da-Silva,Joilson
dos-Santos-Braga,Brenda-Stefany
Da-Silva-Costa,Juliane
Schlemmer-Brasil,Leandro
Lobato-de-Oliveira-Bahia,Verônica-Regina
Pimentel-Leal,Relionan
Felipe-Marques,José-Ribamar
de-Araújo-Guimarães,Diva-Anélie
Sexual dimorphism in the turtle Kinosternon scorpioides (Testudines: Kinosternidae) from Marajó Island, Brazilian Amazon
author_facet Silva-da-Silva,Joilson
dos-Santos-Braga,Brenda-Stefany
Da-Silva-Costa,Juliane
Schlemmer-Brasil,Leandro
Lobato-de-Oliveira-Bahia,Verônica-Regina
Pimentel-Leal,Relionan
Felipe-Marques,José-Ribamar
de-Araújo-Guimarães,Diva-Anélie
author_sort Silva-da-Silva,Joilson
title Sexual dimorphism in the turtle Kinosternon scorpioides (Testudines: Kinosternidae) from Marajó Island, Brazilian Amazon
title_short Sexual dimorphism in the turtle Kinosternon scorpioides (Testudines: Kinosternidae) from Marajó Island, Brazilian Amazon
title_full Sexual dimorphism in the turtle Kinosternon scorpioides (Testudines: Kinosternidae) from Marajó Island, Brazilian Amazon
title_fullStr Sexual dimorphism in the turtle Kinosternon scorpioides (Testudines: Kinosternidae) from Marajó Island, Brazilian Amazon
title_full_unstemmed Sexual dimorphism in the turtle Kinosternon scorpioides (Testudines: Kinosternidae) from Marajó Island, Brazilian Amazon
title_sort sexual dimorphism in the turtle kinosternon scorpioides (testudines: kinosternidae) from marajó island, brazilian amazon
description Abstract Introduction: Morphometrics analysis is an efficient and low-cost technique used in studies of sexual dimorphism in turtles. Kinosternon scorpioides scorpioides, scorpion mud turtle, has a wide phenotypic variation, depending on the area of its occurrence. Objective: The objective of this work was to identify the anatomical sexual difference of K. s. scorpioides, adults and hatchlings, through morphometric analysis; and relate the weights of adult animals to environmental factors (temperature and rainfall) in Marajó Island, Brazil. Methods: The sample collection was carried out from March to September 2018, covering both the rainy season (January to July) and the dry season (August to December). For the biometric analysis, 95 adults and 21 hatchlings were used, in which the length and width of the carapace and plastron, height of the shell, and weight were measured (adults only). For the geometric morphometry analysis, 21 adults and 13 hatchlings were used, in which 27 coordinates of anatomical landmarks were inserted in each image of the carapace and 11 in the plastron. Hatchlings were sexed by histology which was enabled by the identification of the ovaries and testicles. Results: The results showed the existence of dimorphism in adults. The plastron and height were higher in females, which had a more rounded carapace than males. This characteristic may be related to the species’ sexual strategy, where males impose copulation. Histologically, it was possible to identify the ovaries and testicles in the hatchlings, but there was no anatomical sexual difference, despite the tendency to differentiate in the analysis of carapace PCA. Conclusions: Sexual dimorphism in K. s. scorpioides may play an important role on its reproductive behavior, which is synchronized with environmental events. This fact suggests that the reproductive strategies of this species would be severely affected by changes in the ecosystem.
publisher Universidad de Costa Rica
publishDate 2021
url http://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0034-77442021000200601
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