Variação sazonal da temperatura corpórea no lagarto Teiú, Tupinambis merianae (Squamata, Lacertilia, Teiidae)
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Data
2005-05-10
Autores
Ribas, Elis Regina [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Com o propósito de obter um perfil da variação sazonal e diária da temperatura corpórea (Tc) do lagarto teiú, T. merianae, sensores/ registradores de temperatura (data-loggers) foram cirurgicamente implantados, em oito espécimes adultos de ambos os sexos.Os lagartos foram mantidos em baias ao ar livre e acompanhados durante um ano. As temperaturas dos microambientes ao sol, na sombra e na toca foram igualmente registradas. A Tc dos teiús mostrou variação sazonal e diária relacionadas às mudanças nas temperaturas dos microambientes e aos ajustes fisiológicos nas taxas de aquecimento e de resfriamento. A Tc média diária seguiu um ritmo circadiano, com temperaturas mínimas no início da manhã, aumento entre 12h e 16h e queda gradual ao final da tarde. A Tc media diária de atividade durante a estação de atividade (agosto/dezembro) ficou em 33,6oC l 1,4 oC. A taxa média de aquecimento foi cinco vezes maior que a de resfriamento durante a estação de atividade, o que permitiu ao animal manter sua Tc acima da temperatura do abrigo e da sombra. Com o declínio da temperatura ambiente em meados do outono, os teiús entram nos abrigos e o ritmo circadiano de variação da Tc diminuiu. Durante a estação de dormência, a Tc máxima diária foi de 20,1oC l 0,7oC e seguiu a variação térmica do abrigo. Durante a estação de atividade, T. merianae controla sua Tc por termorregulação. Nos meses frios o teiú entra em dormência com a queda da Tc, que acompanha passivamente a temperatura da toca.
In order to obtain a profile of the seasonal and daily variation of the body temperature (Tc) of the tegu lizard, Tupinambis merianae, TidBit® electronic data loggers (temperature probes) were surgically implanted in eight adult individuals. The lizards were kept in outdoor pens and monitored over a one year period. Teguþs body temperature showed seasonal and daily variations, which were related to the changes in the temperatures of the microhabitats (sun, shade, and burrow) and, possibly, to changes in heating and cooling rates. The daily average Tc followed a circadian rhythm characterized by lowest temperatures occurring at dawn, then temperature rapidly increases from soon after sunrise until noon, Tc is then maintained in high levels until late afternoon (~16h) when the lizards stop activity, retreat to the burrow, and let body temperature to drop. The mean Tc experienced by the tegus during activity at the warm season (August/December) was 33.6 oC l 1,4 oC. During the active season, the heating rate of the lizards during the morning was five times greater than the cooling rate experienced during the night. As a result, tegus seems to be able to maintain their Tc above the temperature of the burrow and of the shade along the night time. With declining air temperatures towards the end of autumn, tegus enter their burrows, goes into dormancy, and the circadian rhythm in Tc become less prominent. During this season, Tc followed passively the variation of the burrowþs temperature.
In order to obtain a profile of the seasonal and daily variation of the body temperature (Tc) of the tegu lizard, Tupinambis merianae, TidBit® electronic data loggers (temperature probes) were surgically implanted in eight adult individuals. The lizards were kept in outdoor pens and monitored over a one year period. Teguþs body temperature showed seasonal and daily variations, which were related to the changes in the temperatures of the microhabitats (sun, shade, and burrow) and, possibly, to changes in heating and cooling rates. The daily average Tc followed a circadian rhythm characterized by lowest temperatures occurring at dawn, then temperature rapidly increases from soon after sunrise until noon, Tc is then maintained in high levels until late afternoon (~16h) when the lizards stop activity, retreat to the burrow, and let body temperature to drop. The mean Tc experienced by the tegus during activity at the warm season (August/December) was 33.6 oC l 1,4 oC. During the active season, the heating rate of the lizards during the morning was five times greater than the cooling rate experienced during the night. As a result, tegus seems to be able to maintain their Tc above the temperature of the burrow and of the shade along the night time. With declining air temperatures towards the end of autumn, tegus enter their burrows, goes into dormancy, and the circadian rhythm in Tc become less prominent. During this season, Tc followed passively the variation of the burrowþs temperature.
Descrição
Palavras-chave
Reptil, Dormência, Depressão metabólica, Termorregulação, Lizards - Body temperature
Como citar
RIBAS, Elis Regina. Variação sazonal da temperatura corpórea no lagarto Teiú, Tupinambis merianae (Squamata, Lacertilia, Teiidae). 2005. ix, 64 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências, 2005.