Deep secrets

be hypothesised that adaptation to pollinators has been a driving force behind the diversification of some of the major elements of the southern African flora, " Johnson writes. Southern African flowers are known to be attractive to a range of species from long-probscid flies, oil-bees, hawkmoths, butterflies, birds and rodents. Many of these pollination interactions have been characterised in detail down to the level of particular groups of flowering plants. These groups " tend to be geographically restricted, often exhibiting a short phenophase, and include many unrelated plants that tend to exhibit convergent floral traits, " Johnson says. However, some plant families in southern Africa tend to be dominated by species with specialised pollination systems, he says. " An analysis of existing pollinator data for 114 southern African species of Iridaceae and Orchidaceae revealed that these have a single pollinator species. By contrast, temperate northern hemisphere species of Orchidaceae have a median of five pollinators, he says. This suggests that the specialisation in these families in southern Africa is not simply a phylogenetic effect, but reflects the uneven global distribution of certain specialised pollination system niches, he says. Johnson identifies five different modes of pollinator-driven diversification: pollination system shifts, divergent use of the same pollinator, coevolution, trait-tracking and mimicry. " Darwin's evolutionary framework provided pollination biology with the tools needed to explain how and why flowers diversified, " he writes. " However, there are still few studies that sufficiently explain why flowers have diverged between populations, and ultimately between species. Answers to these questions are fundamental for understanding why some plant groups have diverged under selection by pollinators, while others have not. " Southern Africa remains a remarkable habitat for investigating these questions. " Unlike much of the developed world, southern Africa still has vast tracts of land that are pristine enough to be considered representative of the environment in which plants diversified. " Future research will " have to be devoted to improving our understanding of the role of pollination niches for the maintenance of plant species diversity, " Johnson says. The European eel, and its other relatives that spend much of their adult life in freshwater habitats, have not only long puzzled locals that wondered about its life cycle but also researchers who were intrigued about these fish. The fish, a target for fishermen for centuries, is becoming increasingly scarce, raising concerns amongst conservationists about its extraordinary life …