RESUMEN
Fluctuating asymmetry, defined as random differences between the two sides of a symmetrical structure, has been often related to development stress in both plants and animals. In plants, leaf fluctuating asymmetry has been related to stresses such as pollution and fire and may also be related to leaf growth and herbivory rates. We assessed whether leaf fluctuating asymmetry is related to plant and leaf size in Miconia albicans (Sw.) Triana (Melastomataceae), a common multi-stem Neotropical shrub, in a Brazilian savanna area. We collected 15 leaves from each of 70 individuals, and measured fluctuating asymmetry as the difference in area between the right and left sides of the leaves using the central vein as reference. To avoid spurious results due to measurement error, the division along the central vein was performed independently by three researchers. We also measured the basal area and height of each stem of the plant individuals. We used linear models to assess the relations between leaf fluctuating asymmetry, plant size and leaf size. No consistent relations were observed between leaf fluctuating asymmetry and plant size, as the analyses performed on the fluctuating asymmetry values obtained by the different researchers showed different results. However, relative fluctuating asymmetry values, obtained by dividing the fluctuating asymmetry by the total leaf area, tended to be smaller in larger leaves. It thus appears that, in the study species, fluctuating asymmetry is related to the developmental conditions faced by the individual leaves and not by the plant as a whole.
A assimetria flutuante, definida como diferenças aleatórias entre os dois lados de uma estrutura simétrica, tem sido frequentemente relacionada ao estresse de desenvolvimento em plantas e animais. Nas plantas, a assimetria flutuante foliar tem sido relacionada a estresses como poluição e fogo e também pode estar relacionada ao crescimento foliar e taxas de herbivoria. Nós avaliamos se a assimetria flutuante foliar está relacionada ao tamanho da planta e da folha em Miconia albicans (Sw.) Triana (Melastomataceae), um arbusto neotropical multicaule comum, em uma área de Cerrado. Coletamos 15 folhas de cada um dos 70 indivíduos e medimos a assimetria flutuante como a diferença de área entre os lados direito e esquerdo das folhas usando a nervura central como referência. Para evitar resultados espúrios devido ao erro de medição, a separação ao longo da nervura centra foi feita independentemente por três pesquisadoras/es. Também medimos a área basal e a altura de cada caule de cada planta. Usamos modelos lineares para avaliar as relações entre assimetria flutuante foliar, tamanho da planta e tamanho da folha. Não foram observadas relações consistentes entre a assimetria flutuante da folha e o tamanho da planta, pois as análises realizadas nos valores da assimetria flutuante obtidos pelas/os diferentes pesquisadoras/es mostraram resultados diferentes. No entanto, os valores de assimetria flutuante relativa, obtidos pela divisão da assimetria flutuante pela área foliar total, tenderam a ser menores nas folhas maiores. Assim, verifica-se que, na espécie estudada, a assimetria flutuante está relacionada às condições de desenvolvimento enfrentadas pelas folhas individuais e não pela planta como um todo.
Asunto(s)
Contaminación Ambiental , Desarrollo de la Planta/fisiología , Incendios , Brasil , PraderaRESUMEN
Fluctuating asymmetry, defined as random differences between the two sides of a symmetrical structure, has been often related to development stress in both plants and animals. In plants, leaf fluctuating asymmetry has been related to stresses such as pollution and fire and may also be related to leaf growth and herbivory rates. We assessed whether leaf fluctuating asymmetry is related to plant and leaf size in Miconia albicans (Sw.) Triana (Melastomataceae), a common multi-stem Neotropical shrub, in a Brazilian savanna area. We collected 15 leaves from each of 70 individuals, and measured fluctuating asymmetry as the difference in area between the right and left sides of the leaves using the central vein as reference. To avoid spurious results due to measurement error, the division along the central vein was performed independently by three researchers. We also measured the basal area and height of each stem of the plant individuals. We used linear models to assess the relations between leaf fluctuating asymmetry, plant size and leaf size. No consistent relations were observed between leaf fluctuating asymmetry and plant size, as the analyses performed on the fluctuating asymmetry values obtained by the different researchers showed different results. However, relative fluctuating asymmetry values, obtained by dividing the fluctuating asymmetry by the total leaf area, tended to be smaller in larger leaves. It thus appears that, in the study species, fluctuating asymmetry is related to the developmental conditions faced by the individual leaves and not by the plant as a whole.