Elevational gradients in β-diversity reflect variation in the strength of local community assembly mechanisms across spatial scales.

Despite long-standing interest in elevational-diversity gradients, little is known about the processes that cause changes in the compositional variation of communities (β-diversity) across elevations. Recent studies have suggested that β-diversity gradients are driven by variation in species pools, rather than by variation in the strength of local community assembly mechanisms such as dispersal limitation, environmental filtering, or local biotic interactions. However, tests of this hypothesis have been limited to very small spatial scales that limit inferences about how the relative importance of assembly mechanisms may change across spatial scales.

Selective logging: does the imprint remain on tree structure and composition after 45 years?

Selective logging of tropical forests is increasing in extent and intensity. The duration over which impacts of selective logging persist, however, remains an unresolved question, particularly for African forests. Here, we investigate the extent to which a past selective logging event continues to leave its imprint on different components of an East African forest 45 years later.

C2 photosynthesis generates about 3-fold elevated leaf CO2 levels in the C3-C4 intermediate species Flaveria pubescens.

Formation of a photorespiration-based CO2-concentrating mechanism in C3-C4 intermediate plants is seen as a prerequisite for the evolution of C4 photosynthesis, but it is not known how efficient this mechanism is. Here, using in vivo Rubisco carboxylation-to-oxygenation ratios as a proxy to assess relative intraplastidial CO2 levels is suggested. Such ratios were determined for the C3-C4 intermediate species Flaveria pubescens compared with the closely related C3 plant F.

Radial variation in wood specific gravity of tropical tree species differing in growth-mortality strategies.

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Premise Of The Study: Wood specific gravity (WSG) mediates an interspecific trade-off between growth and mortality and is a key measure for estimating carbon stocks. Most studies use species mean values to represent WSG, despite variation at different levels of biological organization. We examined sources of variation in WSG across four nested scales (segments within cores, cores within trees, trees within species, and species), compared the pattern of radial variation in WSG among species differing in growth strategies, and investigated the effect of WSG radial variation on aboveground biomass estimates.

Characterizing scale-dependent community assembly using the functional-diversity--area relationship.

Phenotypic traits mediate organisms' interactions with the environment and determine how they affect and are affected by their biotic and abiotic milieu. Thus, dispersion of trait values, or functional diversity (FD) of a community can offer insights into processes driving community assembly. For example, underdispersion of FD suggests that habitat "filtering" of species with unfavorable trait values restricts the species that can exist in a particular habitat, while even spacing of FD suggests that interspecific competition, or biotic "sorting," discourages the coexistence of species with similar trait values.

Three keys to the radiation of angiosperms into freezing environments.

Early flowering plants are thought to have been woody species restricted to warm habitats. This lineage has since radiated into almost every climate, with manifold growth forms. As angiosperms spread and climate changed, they evolved mechanisms to cope with episodic freezing.

Effects of detectability on estimates of geographic range size in Bignonieae.

Extinction risk has not been evaluated for 96% of all described plant species. Given that the Global Strategy for Plant Conservation proposes preliminary conservation assessments of all described plant species by 2010, herbarium specimens (i.e.

Untangling the phylogeny of neotropical lianas (Bignonieae, Bignoniaceae).

The tribe Bignonieae (Bignoniaceae) is a large and morphologically diverse clade of neotropical lianas. Despite being a conspicuous component of the neotropical flora, the systematics of the tribe has remained uncertain due to confusing patterns of morphological variation within the group. Chloroplast (ndhF) and nuclear (PepC) DNA sequences were used here to reconstruct the phylogeny of Bignonieae.