Ecological differentiation and local adaptation in two sister species of Neotropical Costus (Costaceae).

Reciprocal transplant experiments have often provided evidence of local adaptation in temperate plants, but few such studies have been conducted in the tropics. To enhance our knowledge of local adaptation in tropical plants, we studied natural populations of two recently diverged Neotropical plant species, Costus allenii and C. villosissimus, in central Panama. We found that these species display a parapatric distribution that reflects local environmental differences on a fine geographic scale: C. allenii is found along ravines in the understory of primary forest, while C. villosissimus is found along forest edges. Light availability was lower in C. allenii habitats, while precipitation and soil moisture were lower in C. villosissimus habitats. We carried out reciprocal transplant experiments with seeds and clones of mature plants to test the hypothesis that the parapatric distribution of these species is due to divergent adaptation to their local habitats. We found strong evidence of local adaptation, i.e., when grown in their "home" sites, each species outperformed the species from an "away" site. Our finding that C. allenii and C. villosissimus are mainly isolated by their microhabitats provides a first step toward understanding the mechanisms of adaptation and speciation in the tropics.

The evolution of postpollination reproductive isolation in Costus.

Reproductive isolation is critical to the diversification of species. Postpollination barriers may be important in limiting gene flow between closely related species, but they are relatively cryptic and their evolution is poorly understood. Here, we review the role of postpollination reproductive isolation in plants, including the various stages at which it operates and the hypotheses for how it may evolve. We then review empirical studies in the plant genus Costus, evaluating documented postpollination barriers in light of these hypotheses. We summarize isolation due to parental style length differences and present evidence supporting the hypothesis that the differences are in part a by-product of selection on floral morphology. Additionally, we show that reduced pollen adhesion, germination, and tube growth contribute to reproductive isolation between two closely related sympatric species of Costus. Geographic variation in the strength of these crossing barriers supports the hypothesis that they evolved under reinforcement, or direct natural selection to strengthen isolation.

[Studies on chemical constituents of two plants from Costus].

OBJECTIVE: To study the chemical constituents of Costus speciosus and C. tonkinensis (Zingiberaceae) distributed in Yunnan province. METHOD: Chromatography and spectral analyses were used to isolate the constituents and elucidate their structure. RESULT: Six compounds were isolated from the rhizome of C. speciosus and elucidated as diosgenin(1), prosapogenin B of dioscin(2), diosgenone(3), cycloartanol(4), 25-en-cycloartenol(5) and octacosanoic acid(6). Four compounds were isolated from the rhizome of Costus tonkinensis and elucidated as tetracosanoic acid(7), succinic acid(8), beta-sitosterol(9) and daucosterin(10). CONCLUSION: Compounds of 3-6 were obtained from C. speciosus for the first time and compounds of 7-10 were obtained from C. tonkinensis for the first time too.

Tamizaje fitoquímico, actividad analgésica y antiinflamatoria de decocción de Costus pictus D Don / Phytochemical screening, analgesic and antiinflammatory properties of Costus pictus D Don decoction

Introducción: Costus pictus D Don (caña mexicana) es una especie cultivada como ornamental y la decocción de hojas y tallos frescos se emplea tradicionalmente para afecciones urinarias, como infecciones, litiasis y cólicos renales en Cuba. Objetivos: identificar los principales grupos de metabolitos secundarios y validar la actividad analgésica y antiinflamatoria de la decocción de hojas y tallos frescos de C. pictus. Métodos: se identificaron los principales grupos de metabolitos secundarios presentes en la decocción mediante un tamizaje fitoquímico. Se evaluó en los modelos farmacológicos de granuloma inducido por algodón en ratas, retorcimientos inducidos por ácido acético 0,75 por ciento (0,1 mL/10 g intraperitoneal) y retirada de la cola inmersa en agua a 55 °C en ratones; las dosis administradas, por vía oral, fueron equivalentes a 0,5; 1 y 5 g de material vegetal fresco/kg de peso corporal. Resultados: la decocción mostró presencia de flavonoides, compuestos fenólicos, compuestos lactónicos y cumarinas, saponinas y azúcares reductores. Inhibió significativamente la respuesta dolorosa en ambos modelos, pero no tuvo efecto antiinflamatorio en el granuloma provocado por algodón. Conclusiones: los resultados contribuyen a validar el uso tradicional de la decocción de hojas y tallos frescos de C. pictus para aliviar el dolor por causa de afecciones renales

Introduction: Costus pictus D Don (Mexican reed) is a species for decorative purposes and the decoction of leaves and fresh stems is traditionally used for urinary disorders like infections, lithiasis and renal colic in Cuba. Objectives: to identify the main groups of secondary metabolites and to validate the analgesic and anti-inflammatory properties of a decoction of fresh leaves and stems from C. pictus. Methods: the main groups of secondary metabolites present in the decoction were identified by a phytochemical screening. The decoction was evaluated in pharmacological models of cotton-induced granulomas in rats; 0,75 por ciento acetic acid-induced cramps (0.1 mL/10 g intraperitoneal) and removal of the tail submerged into water at 55 °C in mice; the orally administered doses were 0.5; 1 and 5 g of fresh vegetable material/kg of body weight. Results: the decoction disclosed the presence of flavonoids, phenolic compounds, lactonic compounds and coumarins, saponins, and reducing sugars. It significantly reduced the painful response both models, but there was no antinflammatory effect on cotton-induced granuloma. Conclusions: the results contributed to validate the traditional use of C. pictus fresh leaves and stems in order to relieve the pain caused by renal diseases