Publicação
Variations of testosterone level in serum of an adult male California sea lion (Zalophus californianus) under human care at Loro Parque
| Resumo: | ABSTRACT - Testosterone concentrations can provide important information about the animals’ breeding season. Although not many studies have been carried out to describe how testosterone concentrations vary in captive and free-living California sea lions (Zalophus californianus). This work aims to study the variation of testosterone levels in an adult male California sea lion under human care, as well as relate those concentrations with breeding season events and evaluate which environmental variables may or may not have influence in the reproduction. In our study we included 26 testosterone concentrations measured from a single male housed at Loro Parque (Tenerife), between April 2019 and February 2024. These concentrations were measured from its blood serum and determined with the VIDAS® Testosterone II (TES2) quantitative test, using the Enzyme Linked Fluorescent Assay technique. We also studied the potential influence of Tenerife’s latitude, daylength and average temperature on the testosterone detectability. From the 26 concentrations measured, 69% (18/26) were non-detectable and 31% (8/26) were detectable by the VIDAS® equipment, ranging between < 0.05 ng/mL and 0.83 ng/mL. These concentrations also showed some cyclical variation between reproductive seasons, becoming detectable around April/May, reaching a peak around June, becoming once again non-detectable in the second half of August, and remaining like this until the following reproductive season. 75% (6/8) of the detectable concentrations were collected in a day with a daylength above 13 hours, suggesting that daylength has an influence in the testosterone detectability. However, the opposite was observed for the temperature, and as for latitude, the results were not very conclusive, although suggesting that other factors may have the capacity to influence reproduction. Our findings improve the knowledge about California sea lions’ reproduction and testosterone variations and may have opened many doors for future studies that will help to better understand what really influences them |
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| Autores principais: | Silva, Mariana de Sousa Sá |
| Assunto: | Zalophus californianus Testosterone Breeding seasons Environmental factors Animal reproduction Zalophus californianus Testosterona Época de reprodução Fator ambiental Reprodução animal |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | ABSTRACT - Testosterone concentrations can provide important information about the animals’ breeding season. Although not many studies have been carried out to describe how testosterone concentrations vary in captive and free-living California sea lions (Zalophus californianus). This work aims to study the variation of testosterone levels in an adult male California sea lion under human care, as well as relate those concentrations with breeding season events and evaluate which environmental variables may or may not have influence in the reproduction. In our study we included 26 testosterone concentrations measured from a single male housed at Loro Parque (Tenerife), between April 2019 and February 2024. These concentrations were measured from its blood serum and determined with the VIDAS® Testosterone II (TES2) quantitative test, using the Enzyme Linked Fluorescent Assay technique. We also studied the potential influence of Tenerife’s latitude, daylength and average temperature on the testosterone detectability. From the 26 concentrations measured, 69% (18/26) were non-detectable and 31% (8/26) were detectable by the VIDAS® equipment, ranging between < 0.05 ng/mL and 0.83 ng/mL. These concentrations also showed some cyclical variation between reproductive seasons, becoming detectable around April/May, reaching a peak around June, becoming once again non-detectable in the second half of August, and remaining like this until the following reproductive season. 75% (6/8) of the detectable concentrations were collected in a day with a daylength above 13 hours, suggesting that daylength has an influence in the testosterone detectability. However, the opposite was observed for the temperature, and as for latitude, the results were not very conclusive, although suggesting that other factors may have the capacity to influence reproduction. Our findings improve the knowledge about California sea lions’ reproduction and testosterone variations and may have opened many doors for future studies that will help to better understand what really influences them |
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