Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades.

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Background and Aims Bat-pollination is an important system in terms of occurrence and distribution, although it remains little studied. Thus, the role of particular flower traits in this interaction remains uncertain. Flower height along the shoot axis, associated with flower exposure, has often been deemed a key trait in this system, but its effect on fitness has not previously been assessed. We aimed to test its role and propose that taller flowers attain higher fitness due to a higher degree of accessibility and conspicuity to foraging bats. Methods We assessed the effect of floral height on bat visiting rates to individual flowers of Crescentia cujete (Bignoniaceae), a cauliflorous model bat-pollinated species with a marked gradient in flower height along the shoot axis. Additionally, we tested the effect of this variable on seed/ovule ratio measurements from seven other species from different families along a herb–tree gradient. Hypotheses were tested through mixed-effect linear models. Key Results Bat visiting rates varied positively as a function of flower height in C. cujete, but significance was found only for the subset of flowers located on the trunk, closer to the ground. Similarly, seed/ovule ratios were positively correlated with flower height only for the three species with the shortest statures along the height gradient and shortest average floral heights. These results suggest that proximity to the ground, associated with herbaceous or bushy surrounding vegetation, may be an obstacle to the foraging of nectar-feeding bats, which in turn should explain the morphological convergence of inflorescence length and exposure strategies of short-statured bat-pollinated plants. Conclusions Flower height has a species-specific effect on plant fitness. This study provides a novel numerical perspective to the role of an unexplored trait in bat-pollination, and has elucidated some aspects of the adaptive importance of flower height based on limitations imposed by ecologically complex pollinators.

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Woody plant resprouting has received considerable attention in the last two decades as human disturbances continue to encroach on terrestrial ecosystems globally. We examined the regeneration mechanisms of a Caatinga dry forest in the context of slash-and-burn agriculture and resprouting ability of the local flora. We excavated two old fields (from 32) experiencing early forest regeneration dominated by the tree Pityrocarpa moniliformis (Fabaceae) to map clonal propagation and, in parallel, submitted 260 seedlings from 13 woody plant species to experimental clipping. What seemed to be ‘seedlings’ popping up around P. moniliformis stumps and remaining adults actually were condensed sets of root suckers connected via complex networks of long, ramified shallow horizontal roots without taproots. We mapped respectively 39 and 783 connected root suckers, which summed 96 m and 910 m in root length. Regarding the seedlings, 33% resprouted across nine species with resprouting rates varying between 5–100%. Seedling height before clipping positively influenced resprouting vigour. Our preliminary results suggest that the Caatinga dry forest supports a relatively high proportion of resprouting species, some of them able to clonally propagate and playing an ecosystem-level role by responding to early forest regeneration and high abundance/biomass across both regenerating and old-growth forests.

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