RESUMO
La plasticidad fenotípica es uno de los medios por los cuales las plantas pueden ajustar su morfología y fisiología, permitiéndoles enfrentar la heterogeneidad ambiental bajo condiciones naturales. El presente estudio evaluó la plasticidad fenotípica (PF) en respuesta a la disponibilidad hídrica del suelo, bajo dos condiciones de luz, en clones de dos poblaciones de Lippia alba (Verbanaceae) contrastantes en la heterogeneidad del régimen de precipitación en su hábitat natural, a través de normas de reacción morfológicas y de asignación de biomasa. El experimento se desarrolló en condiciones semicontroladas en invernadero, siguiendo un diseño experimental completamente aleatorizado, bajo un esquema factorial dos * dos (disponibilidad hídrica y poblaciones). La mayoría de los caracteres evaluados mostraron PF. No obstante, algunos caracteres de la población proveniente de condiciones naturales más homogéneas presentaron una reducción de plasticidad marcada. Lo anterior sugiere una posible relación entre el amplio rango de distribución de Lippia alba, PF y eventos de adaptación local.
The phenotypic plasticity is one possible way for plants to adjust their morphology and physiology to cope with the environmental heterogeneity of their natural conditions. This study tested the phenotypic plasticity (PF) in response to soil water availability, under two light conditions, in clones of two populations of Lippia alba (Verbanaceae), which show differences in the precipitation heterogeneity, using morphological and biomass allocation reaction norms. The experiment was conducted in a greenhouse under semi-controlled conditions in a random experimental design, under a factorial design of two * two (water availability and populations). The majority of the traits showed PF. Although, some traits of the populations that come from more homogenous conditions showed a significant reduction in plasticity. This could suggest a relationship between the wide ecological breadth of Lippia alba, PF and local adaptation events.
RESUMO
Phenotypic variability for abdominal pigmentation in females of an Indian natural population of Drosophila melanogaster was studied using isofemale lines and by rearing the larvae and pupae at 4 different temperatures ranging from 20–30°C. The dark pigmented area was found to increase in all the three segments when the growth temperature decreases. A significant positive correlation was detected for the occurrence of dark pigmentation in the 5th and 6th segments in each growth temperature but for other comparisons the correlation was not regular. Analysis of variance (ANOVA) was carried out both for individual segments over different growth temperatures and also for each temperature over the three abdominal segments and in all cases found to be statistically significant. The results are quite different from the earlier observation in French Drosophila melanogaster and suggest that genes controlling pigmentation are temperature dependent; temperature could affect post-transitional events involved in pigmentation. The present findings also clearly indicate that significant genotype-environment interaction exists, responsible for the production of desired phenotype at the opportune moment during the life span of a species.