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Ecological Adaptation of the Seed Microsculptures of Saussurea from Different Altitudes (Qinghai-Tibet Plateau)

Li Z., Du G.

Polish Journal of Ecology

2015

Vol. 63, nr 4

593--598

The aim of this study was to explore ecological adaptation of seed microsculptures of Saussurea from different altitudes. Scanning electron microscopy was used to observe the cypselae surface of 10 taxa of Saussurea collected from the eastern edge of Qinghai-Tibet plateau, China. The results indicated that the microsculptures had clear and consistent variations in some samples collected from high (4200 m a.s.l.) and low-altitude sites (2200 m a.s.l.). The thickness of stripes and distance between stripes are increasing while sulcus depth is increasing from a low to a high altitude (P < 0.01). The seed-coat surface was becoming rougher from low to high altitude. The surviving rate of seeds was lower at high altitude than that at low altitude in all the species. The surviving rate of the seeds collected from the high altitudes was higher than that of the seeds collected from low altitudes when sown at the same altitude. All the results suggested that there is selection pressure of the altitude on the development of the microsculpture patterns, which increases absorbed sunlight, the residence time of soil water and nutrition. The changes can make the seeds survive better at extreme environments (cold and dry). The cypselae microsculpture patterns should be used as potential adaptation biomarkers for the species of Saussurea from low- to high-altitude.

Seed mass increase along altitude within four Saussurea (Asteraceae) species in Tibetian Plateau

Wu G., Tian F., Ren G., Liu Z.

Polish Journal of Ecology

2011

Vol. 59, nr 3

617-622

Seed mass is a critical life-history character in seed evolutionary ecology. Plant species can present responses in seed mass to environment stresses. We tested the hypotheses that seed mass was positively correlated with altitude within species. We selected four congeneric Saussurea species as study objects, and collected their seeds along altitudinal gradients (2100.4200 m a.s.l.) in the alpine area of the Qinghai-Tibetan Plateau, China. Results showed that mean seed mass of the four species were significantly affected by altitude (P <0.001). There was a general trend of an increase in seed weight with altitude among the populations of the four species. In addition, mean seed mass of four species were not significantly different, but all presented a bigger coefficients of variation within species along altitude gradients. Our results indicate selection pressure within species, with larger seeds occurring at higher altitudes.