Differences in life history traits of related Epilobium species : clonality, seed size and seed number

Small changes in morphology can affect the performance and functions of organisms and hence their ecological success. In modular constructed plants, contrasting growth strategies may be realized by differences in the spatial arrangement and size of shoots. Such differences change the way in which meristems and resources are assigned to various functions during the lifespan of a plant. If such changes include the capacity to spread clonally, sexual reproduction may also be affected. I compare patterns in vegetative growth and sexual reproductive traits in four allopatric species of Epilobium which are sometimes considered as subspecies of a single polymorphic taxon. The four species differ in the location of the buds which annually renew the aerial shoot system. E. dodonaei and E. steveni do not spread clonally and are characterized by a shrub-like habit. E. fleischeri, a species occurring only in the Alps, and E. colchicum, which occurs in the upper region of the Caucasus mountains, both produce buds on horizontal roots or plagiotropic shoots. Both alpine species exhibiting clonal growth have smaller shoots, fewer fruits and smaller seeds than the lowland species. An intraspecific trade-off between seed number per fruit and seed mass is realized. Both alpine species produce mon seeds per fruit at the expense of seed mass. The morphological relationship between the four species and their geographical distribution suggest that clonal growth in E. fleischeri (restricted to the Alps) and E. colchicum (restricted to the Caucasus) is adaptively associated with the stressful conditions of alpine habitats. Our results suggest that clonal growth is not necessarily correlated with reduced reproduction by seeds. The success of plants which are already established may largely depend on clonal spread, but the colonization of new habitats depends on the production of a large number of small seeds with high dispersability

Doses de fósforo e crescimento radicular de cultivares de arroz de terras altas Phosphorus doses and root growth of upland rice

O estudo de crescimento radicular de arroz de terras altas em função da disponibilidade de fósforo é, praticamente, inexistente. O objetivo deste trabalho foi avaliar o crescimento de diversas cultivares de arroz de terras altas em diferentes condições de disponibilidade de fósforo. O experimento foi desenvolvido em casa de vegetação, em delineamento inteiramente casualizado, em esquema fatorial 4 x 4, com quatro doses de P (0, 50, 100 e 200 mg dm-3) e quatro cultivares: Maravilha (grupo moderno), IAC 201, IAC 202 e Carajás (grupo intermediário). A cultivar Carajás possui sistema radicular que melhor se desenvolveu sob baixa disponibilidade de P. Sob baixa disponibilidade de P as cultivares IAC 201 e IAC 202 priorizaram o desenvolvimento do sistema radicular em relação a parte aérea. A cultivar Maravilha requer níveis elevados de fósforo para atingir o máximo desenvolvimento. Sob baixa disponibilidade de fósforo as cultivares de arroz diminuíram o diâmetro radicular.<br>Very little is known of phosphorus availability for upland rice. The objective of this work was to evaluate root growth of upland rice cultivars in different conditions of phosphorus availability. The experiment was carried out in greenhouse, in a completely randomized design, as a 4 x 4 factorial, with four doses of P (0, 50, 100 and 200 mg dm-3) and four cultivars: Maravilha (modern group), IAC 201, IAC 202 and Carajás (middle group). The Carajás root system grew more in low availability of P than other cultivars. In low availability of P the cultivars IAC 201 and IAC 202 priorized root system growth to aerial growth . The Maravilha cultivar needs high Plevels to reach maximum growth. In low availability of P the upland rice cultivars decreased root diameter

West Wind Drift revisited : testing for directional dispersal in the Southern Hemisphere using event-based tree fitting

Aim Recent studies suggest that if constrained by prevailing wind or ocean currents dispersal may produce predictable, repeated distribution patterns. Dispersal mediated by the West Wind Drift (WWD) and Antarctic Circumpolar Current (AAC) has often been invoked to explain the floristic similarities of Australia, South America and New Zealand. If these systems have been important dispersal vectors then eastward dispersal – from Australia to New Zealand and the western Pacific to South America – is expected to predominate. We investigate whether phylogenies for Southern Hemisphere plant groups provide evidence of historical dispersal asymmetry and more specifically whether inferred asymmetries are consistent with the direction of the WWD/AAC.I.S. is supported by the Swedish Science Research Council (GRANT 621-2003-456). R.C.W. is supported by the Fundac¸a˜o de Amparo a` Pesquisa do Estado de Sa˜o Paulo (Grant 04/09666-2)Peer reviewe