Flower morphological diversity in Aframomum (Zingiberaceae) from Africa – the importance of distinct floral types with presumably specific pollinator associations, differential habitat adaptations and allopatry in speciation and species maintenance

Flower morphological differentiation and plant-pollinator interactions among sympatric Aframomum species (Zingiberaceae) with floral trumpet type in the tropical African rainforest

“…Species of this floral type can be found throughout tropical Africa with the centre of species diversity in Cameroon and the Republic of the Congo. Here, many of these species can be found in sympatry in the same habitat (Ley & Harris 2014). This floral type was hypothesized to be pollinated by medium-sized to small bees (Ley & Harris 2014), however, direct field observations are still lacking (except Lock et al 1977).…”

“…Here, many of these species can be found in sympatry in the same habitat (Ley & Harris 2014). This floral type was hypothesized to be pollinated by medium-sized to small bees (Ley & Harris 2014), however, direct field observations are still lacking (except Lock et al 1977). Due to a lack of genetic studies, there is no evidence of hybridization yet.…”

“…In contrast to these conspicuous floral radiations (e.g. Disa: Johnson et al 1998;Marantaceae: Ley & Claßen-Bockhoff 2011;Costaceae: Ricklefs & Renner 1994, Specht et al 2001Salvia: Wester & Claßen-Bockhoff 2007) there are also plant species that exhibit morphologically very similar floral types (see selected groups of species within Impatiens: Grey-Wilson 1980; Marantaceae: Ley 2008; Aframomum: Ley & Harris 2014). These contradict our expectations of competitive exclusion (either through different pollinator species or mutual pollen incompatibility), or at least suggest a strong possibility of high rates of interspecific pollen transfer.…”

“…Its species are broad leaved perennial herbs from the rainforest understorey, gaps, edges, and savannas distributed from Senegal to Madagascar (Dhetchuvi 1996). They form large conspicuous flowers of five different floral types (trumpet, apron, open, short tube, collar) with one single floral type dominating (trumpet) (Ley & Harris 2014). Based solely on morphological characters and the concept of "pollination syndromes" (Ollerton & Watts 2000), first hypotheses about their pollinating species have been pronounced (Ley & Harris 2014).…”

“…The dominant floral trumpet type in about 60% of all Aframomum species consists of a large pink tubular flower of delicate tissue with a large landing platform and a horizontal to slightly vertical floral entrance with often conspicuous yellow nectar guides (UV patterning is not yet documented) and some variation in size between species (Ley & Harris 2014). Species of this floral type can be found throughout tropical Africa with the centre of species diversity in Cameroon and the Republic of the Congo.…”