Variação sexual no desempenho locomotor e metabolismo de Tomodon dorsatus (Serpentes: Dipsadidae)
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Data
2019-06-25
Autores
Santos, Jade Lima dos [UNIFESP]
Orientadores
Brasileiro, Cinthia Aguirre [UNIFESP]
Tipo
Dissertação de mestrado
Título da Revista
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Resumo
O tamanho do corpo pode influenciar positivamente o desempenho locomotor e a taxa
metabólica de serpentes. Entretanto, a variação na locomoção também pode ser
atribuída ao estado reprodutivo e diferenças no comportamento entre fêmeas e machos.
Tomodon dorsatus é uma serpente diurna, terrícola, malacófaga e vivípara. As fêmeas
possuem maior tamanho corporal e de cabeça quando comparadas com machos. Os
objetivos deste estudo foram investigar a influência da variação sexual no desempenho
locomotor e na atividade metabólica de Tomodon dorsatus e estudar como o
investimento reprodutivo influencia a taxa metabólica aeróbia nesta espécie. Utilizei
como proxy do desempenho locomotor a velocidade de fuga dos indivíduos medida em
uma pista de vidro retangular. Também medi a taxa de consumo de oxigênio (VO2)
como medida da taxa metabólica aeróbia de repouso (TMR) através de um sistema de
respirometria aberta, assim como a atividade máxima das enzimas citrato sintase (CS)
e lactato desidrogenase (LDH) como indicadoras da capacidade metabólica do músculo
esquelético intercostal, fígado e coração. Utilizei a massa dos folículos reprodutivos
das fêmeas e a massa dos testículos e volume testicular dos machos como variáveis
operacionais para o investimento reprodutivo. Machos de Tomodon dorsatus
apresentaram maior desempenho locomotor e maior taxa metabólica aeróbia de repouso
do que as fêmeas. Na atividade enzimática, as vias catalisadas pelas enzimas LDH e CS
não foram influenciadas pelo sexo. Além disto, a taxa metabólica das fêmeas e machos
Tomodon dorsatus foi semelhante independente do investimento reprodutivo. O melhor
desempenho locomotor nos machos Tomodon dorsatus pode estar relacionado a
agressividade dos indivíduos e ao sucesso reprodutivo. Quanto a influência do
investimento reprodutivo na taxa metabólica, é necessário acompanhar todo o período
reprodutivo das fêmeas porque possivelmente o aumento na taxa metabólica ocorre
após a fecundação, atingindo maiores níveis na embriogênese. Para machos, a
espermiogênese teve um baixo custo energético e não influenciou a taxa metabólica dos
indivíduos. Em conclusões, os machos de Tomodon dorsatus são mais velozes do que
as fêmeas e a taxa metabólica não é alterada devido ao investimento reprodutivo de
machos e fêmeas.
Body size may positively influence locomotor performance and the metabolic rate of snakes. However, the variation in locomotion rates can also be attributed to reproductive cycle status, and behavioral differences between females and males. Regarding their traits, Tomodon dorsatus are diurnal, terrestrial, malacophagous and viviparous snakes. They are sexually dimorphic as females have larger body and head size than males. The objectives of this study were 1) to investigate the influence of sexual variation on locomotor performance and metabolic activity of Tomodon dorsatus and 2) to study how reproductive investiment influences the aerobic metabolic rate in this species. To evaluate the locomotor performance of each individual, theescape speed was measured in a rectangular glass lane. We measured the oxygen consumption rate (VO2) as a proxy measure of resting aerobic metabolic rate (MB) through an open respirometry system. In addition, the maximum activity of citrate synthase (CS) and lactate dehydrogenase (LDH) enzymes were measured as indicators of the metabolic capacity of the intercostal skeletal muscle, liver and heart. I used the mass of the reproductive follicles of the females and the testicles and testicular volume of the males as operational variables for the reproductive investment in each individual. Males of Tomodon dorsatus presented higher locomotor performance and higher aerobic resting metabolic rate than females. In addition, the metabolic rate of females and males of Tomodon dorsatus were similar regardless of reproductive investment. The pathways catalyzed by LDH and CS enzymes were also not influenced by sex.The higher locomotor performance in the Tomodon dorsatus males may be related to its aggressiveness and reproductive success. Regarding the influence of the reproductive investment on the metabolic rate, my results indicate that the increase in the metabolic rate in females occurs after the fertilization, reaching higher levels in the embryogenesis. However, it is still necessary to follow the entire female reproductive period to confirm it. since as for the males, spermiogenesis had a low energy cost and did not influence the metabolic rate of the individuals. In conclusions, males of Tomodon dorsatus are faster than females and the metabolic rate is not altered due to the reproductive investment of males and females.
Body size may positively influence locomotor performance and the metabolic rate of snakes. However, the variation in locomotion rates can also be attributed to reproductive cycle status, and behavioral differences between females and males. Regarding their traits, Tomodon dorsatus are diurnal, terrestrial, malacophagous and viviparous snakes. They are sexually dimorphic as females have larger body and head size than males. The objectives of this study were 1) to investigate the influence of sexual variation on locomotor performance and metabolic activity of Tomodon dorsatus and 2) to study how reproductive investiment influences the aerobic metabolic rate in this species. To evaluate the locomotor performance of each individual, theescape speed was measured in a rectangular glass lane. We measured the oxygen consumption rate (VO2) as a proxy measure of resting aerobic metabolic rate (MB) through an open respirometry system. In addition, the maximum activity of citrate synthase (CS) and lactate dehydrogenase (LDH) enzymes were measured as indicators of the metabolic capacity of the intercostal skeletal muscle, liver and heart. I used the mass of the reproductive follicles of the females and the testicles and testicular volume of the males as operational variables for the reproductive investment in each individual. Males of Tomodon dorsatus presented higher locomotor performance and higher aerobic resting metabolic rate than females. In addition, the metabolic rate of females and males of Tomodon dorsatus were similar regardless of reproductive investment. The pathways catalyzed by LDH and CS enzymes were also not influenced by sex.The higher locomotor performance in the Tomodon dorsatus males may be related to its aggressiveness and reproductive success. Regarding the influence of the reproductive investment on the metabolic rate, my results indicate that the increase in the metabolic rate in females occurs after the fertilization, reaching higher levels in the embryogenesis. However, it is still necessary to follow the entire female reproductive period to confirm it. since as for the males, spermiogenesis had a low energy cost and did not influence the metabolic rate of the individuals. In conclusions, males of Tomodon dorsatus are faster than females and the metabolic rate is not altered due to the reproductive investment of males and females.