Efectos multigeneracionales de la temperatura sobre la tolerancia al calor de Drosophila melanogaster.
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Date
2024
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Universidad de Concepción
Abstract
Desde el siglo XX, el planeta ha experimentado un aumento de las temperaturas medias y fenómenos meteorológicos extremos más frecuentes. Frente a estos nuevos desafíos, la capacidad de los organismos y poblaciones de reaccionar con cambios fenotípicos puede ser clave para su persistencia. Se investigó el impacto de la temperatura ambiental experimentada durante múltiples generaciones sobre la tolerancia térmica en Drosophila melanogaster. Estimamos la tolerancia al calor de individuos adultos mantenidos durante 17 generaciones en ambientes térmicos (Ttrat) cada vez más estresantes: 21, 24, 27 y 30°C. La tolerancia al calor se cuantificó empleando curvas de Tiempo de Muerte Térmica (curvas TDT, por sus siglas en inglés), que describen como el tiempo de sobrevivencia de los organismos varía en función de la temperatura (Temperatura de ensayo o Tens). A través de esta metodología se estimaron parámetros que permiten diferenciar el impacto de la intensidad de la temperatura y el tiempo de exposición sobre los organismos: CTmax (Temperatura Critica máxima) que corresponde a la temperatura de colapso o temperatura donde los organismos pierden la capacidad de mantenerse erguidos, y Z una constante que indica la sensibilidad al cambio de temperatura. Nuestros resultados revelaron que Ttrat indujo cambios en la tolerancia térmica de Drosophila melanogaster. El tiempo de sobrevivencia de hembras fue 29% superior al de los machos, y la Tens afectó negativa y significativamente el tiempo de sobrevivencia de D. melanogaster. Los organismos mantenidos a 24, 27 y 30ºC durante múltiples generaciones sobrevivieron en promedio 3, 11 y 10% más tiempo que sus contrapartes mantenidas a 21ºC. Encontramos interacciones significativas entre Ttrat y Tens, los individuos de los tratamientos de 27 y 30°C disminuyen su sobrevivencia en las temperaturas extremadamente altas (39 y 40°C). Finalmente, nuestros resultados revelaron un compromiso entre CTmax y sensibilidad Z, estos resultados proporcionan nueva evidencia sobre el impacto al largo plazo de la temperatura sobre el desempeño térmico de los organismos.
Since the 20th century, the planet has experienced rising average temperatures and more frequent extreme weather events. In the face of these new challenges, the ability of organisms and populations to respond with phenotypic changes may be key to their persistence. We studied the effect of temperature experienced over multiple generations on thermal tolerance in Drosophila melanogaster. We estimated the heat tolerance of adult individuals maintained over 17 generations in increasingly stressful thermal environments (Ttrat): 21, 24, 27 and 30°C. Heat tolerance was quantified using Thermal Death Time curves (TDT curves), which describe how the survival time of organisms varies as a function of temperature (test temperature or Tens). This method allowed the estimation of parameters that differentiate the effects of temperature intensity and exposure time: CTmax (Maximum Critical Temperature), which corresponds to the collapse temperature or the temperature at which the organisms lose the ability to remain upright, and Z, a constant that indicates the sensitivity to temperature changes. Our results showed that Ttrat induced changes in the thermal tolerance of Drosophila melanogaster. The survival time of females was 29% higher than that of males, and Tens had a negative and significant effect on the survival time of D. melanogaster. Organisms maintained at 24, 27 and 30ºC survived on average 3, 11 and 10% longer than their counterparts maintained at 21ºC. We found significant interactions between Ttrat y Tens, individuals in the 27 and 30°C treatments decreased their survival at extremely high temperatures (39 and 40°C). Finally, our results revealed a trade-off between CTmax and Z, these results provide new evidence on the long-term effects of temperature on the thermal tolerance of organisms.
Since the 20th century, the planet has experienced rising average temperatures and more frequent extreme weather events. In the face of these new challenges, the ability of organisms and populations to respond with phenotypic changes may be key to their persistence. We studied the effect of temperature experienced over multiple generations on thermal tolerance in Drosophila melanogaster. We estimated the heat tolerance of adult individuals maintained over 17 generations in increasingly stressful thermal environments (Ttrat): 21, 24, 27 and 30°C. Heat tolerance was quantified using Thermal Death Time curves (TDT curves), which describe how the survival time of organisms varies as a function of temperature (test temperature or Tens). This method allowed the estimation of parameters that differentiate the effects of temperature intensity and exposure time: CTmax (Maximum Critical Temperature), which corresponds to the collapse temperature or the temperature at which the organisms lose the ability to remain upright, and Z, a constant that indicates the sensitivity to temperature changes. Our results showed that Ttrat induced changes in the thermal tolerance of Drosophila melanogaster. The survival time of females was 29% higher than that of males, and Tens had a negative and significant effect on the survival time of D. melanogaster. Organisms maintained at 24, 27 and 30ºC survived on average 3, 11 and 10% longer than their counterparts maintained at 21ºC. We found significant interactions between Ttrat y Tens, individuals in the 27 and 30°C treatments decreased their survival at extremely high temperatures (39 and 40°C). Finally, our results revealed a trade-off between CTmax and Z, these results provide new evidence on the long-term effects of temperature on the thermal tolerance of organisms.
Description
Tesis presentada para optar al título profesional de Bióloga
Keywords
Drosophila melanogaster, Biología evolutiva, Adaptación (Biología)