Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus
This study describes sex-steroid cycles of free-living male and female Bolson tortoises at the Mapimi Biosphere Reserve in northeastern Durango, Mexico. Blood samples were taken at biweekly intervals during a 14 month period by jugular venipuncture, and plasma levels of steroids were determined usin...
| Autori principali: | , , |
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| Natura: | Online |
| Lingua: | eng |
| Pubblicazione: |
Instituto de Ecología, A.C.
2000
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| Accesso online: | https://azm.ojs.inecol.mx/index.php/azm/article/view/1893 |
| _version_ | 1799770308774723584 |
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| author | González Trápaga, Rolando Aguirre, Gustavo Adest, Gary A. |
| author_facet | González Trápaga, Rolando Aguirre, Gustavo Adest, Gary A. |
| author_sort | González Trápaga, Rolando |
| collection | AZM |
| description | This study describes sex-steroid cycles of free-living male and female Bolson tortoises at the Mapimi Biosphere Reserve in northeastern Durango, Mexico. Blood samples were taken at biweekly intervals during a 14 month period by jugular venipuncture, and plasma levels of steroids were determined using radioimmunoassays. Hormone levels showed seasonal trends. In females testosterone peaked following emergence, associated with increased sexual receptivity, and estradiol increased after emergence in association with follicular maturation. These two steroids increased with seasonal rains, when follicular enlargement and vitellogenesis occurred. Females emerged from brumation with low levels of progesterone, which increased with daylength and temperature and reached a maximum before the peak of egg-laying. Declines in all three hormones were associated with oviposition. Females probably store sperm during brumation for use during the following season. Males emerged after brumation with low testosterone levels and soon exhibited reproductive behavior. Along with a testosterone rise, mating and courtship increased with environmental cues and extended until early fall. Testosterone levels and reproductive activity decreased as brumation approached. Male peak testosterone levels are higher than those reported for any vertebrate. |
| format | Online |
| id | azm-article-1893 |
| institution | Acta Zoológica Mexicana |
| language | eng |
| publishDate | 2000 |
| publisher | Instituto de Ecología, A.C. |
| record_format | ojs |
| spelling | azm-article-18932022-09-22T00:07:57Z Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus González Trápaga, Rolando Aguirre, Gustavo Adest, Gary A. Gopherus flavomarginatus Reproduction Seasonal cycles Hormones. Gopherus flavomarginatus Reproducción Ciclos estacionales Hormonas. This study describes sex-steroid cycles of free-living male and female Bolson tortoises at the Mapimi Biosphere Reserve in northeastern Durango, Mexico. Blood samples were taken at biweekly intervals during a 14 month period by jugular venipuncture, and plasma levels of steroids were determined using radioimmunoassays. Hormone levels showed seasonal trends. In females testosterone peaked following emergence, associated with increased sexual receptivity, and estradiol increased after emergence in association with follicular maturation. These two steroids increased with seasonal rains, when follicular enlargement and vitellogenesis occurred. Females emerged from brumation with low levels of progesterone, which increased with daylength and temperature and reached a maximum before the peak of egg-laying. Declines in all three hormones were associated with oviposition. Females probably store sperm during brumation for use during the following season. Males emerged after brumation with low testosterone levels and soon exhibited reproductive behavior. Along with a testosterone rise, mating and courtship increased with environmental cues and extended until early fall. Testosterone levels and reproductive activity decreased as brumation approached. Male peak testosterone levels are higher than those reported for any vertebrate. Estudiamos los ciclos de esteroides sexuales de machos y hembras en estado silvestre de la tortuga del Bolsón en la Reserva de la Biósfera de Mapimí (Durango). Tomamos muestras de sangre por venipunción de la yugular a intervalos bisemanales durante un período de 14 meses, determinándose los niveles circulantes de esteroides por medio de radioinmunoensayos. Los niveles hormonales mostraron tendencias estacionales. En las hembras, la testosterona tuvo un valor máximo al salir de la brumación, en asociación con el incremento en la receptividad sexual, y el nivel de estradiol aumentó después de la emergencia asociado con la maduración folicular. El nivel de estos dos esteroides se incrementó con las lluvias estacionales, cuando ocurrieron el crecimiento folicular y la vitelogénesis. La progesterona mostró niveles bajos a la emergencia, los cuales aumentaron con el incremento de la duración del dia y la temperatura, llegando al máximo antes del pico de la oviposición. La caída en los niveles de las tres hormonas estuvo asociada con la oviposición. Las hembras probablemente almacenan esperma durante parte del otoño y el invierno para usarlo en la siguiente estación reproductiva. Los machos salieron de la hibernación con bajos niveles de testosterona, pero exhibieron conductas reproductivas poco después. Junto con un incremento de la testosterona, el cortejo y la frecuencia de apareamientos se incrementaron con estímulos ambientales, prolongándose hasta principios del otoño. Los niveles de testosterona y la actividad reproductiva disminuyeron conforme se aproximaba el inicio de la hibernación. Los niveles máximos de testosterona en machos de esta especie son mayores que los conocidos para cualquier otro vertebrado. Instituto de Ecología, A.C. 2000-08-16 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Original articles Artículos originales application/pdf https://azm.ojs.inecol.mx/index.php/azm/article/view/1893 10.21829/azm.2000.80801893 ACTA ZOOLÓGICA MEXICANA (N.S.); No. 80 (2000); 101-117 ACTA ZOOLÓGICA MEXICANA (N.S.); Núm. 80 (2000); 101-117 2448-8445 0065-1737 eng https://azm.ojs.inecol.mx/index.php/azm/article/view/1893/2007 Derechos de autor 2018 Acta Zoológica Mexicana (parte1) http://creativecommons.org/licenses/by-nc-sa/4.0 |
| spellingShingle | González Trápaga, Rolando Aguirre, Gustavo Adest, Gary A. Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus |
| title | Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus |
| title_full | Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus |
| title_fullStr | Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus |
| title_full_unstemmed | Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus |
| title_short | Sex-steroids associated with the reproductive cycle in male and female Bolson tortoise, Gopherus flavomarginatus |
| title_sort | sex-steroids associated with the reproductive cycle in male and female bolson tortoise, gopherus flavomarginatus |
| url | https://azm.ojs.inecol.mx/index.php/azm/article/view/1893 |
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