How plant species evolve
The aim of the EU-funded project LINARIA-SPECIATION (Integrating phylogenetics, ecology and evo-devo to understand the origin of plant species: the role of spur length evolution in speciation of the genus Linaria) was to understand speciation processes in plants. Researchers studied the role of floral nectar spurs, which may be a key innovation promoting speciation in angiosperms as a result of pollinator interactions. Investigations centred on snapdragons (Antirrhineae), a model group for research into plant development and evolution. The genus Linaria (toadflxes) is the most diverse within the (Antirrhineae) and provides an ideal system for investigating pollinator-driven speciation as it displays several flower traits linked to pollinator specialisation. They include a spur of variable length that collects nectar, which is offered to the pollinator. Scientists investigated phylogenetic relationships within a clade of eight toadflaxes from biodiversity hotspots in the Iberian Peninsula. This was used to reconstruct evolutionary changes in floral traits (including nectar spur length) in the course of speciation. In addition, researchers investigated the components of reproductive isolation among species of the study clade and sought to understand the genetic and developmental and genetic basis of spur length variation. Detailed analysis of the Iberian clade of Linaria suggested that specific mechanisms involved in spur length changes in the course of speciation may not always fit the conventional ′pollinator shift′ model. This posits that changes in spur length are associated with changes between pollinators with different proboscis length. Instead, the evolution of a short spur in L. clementei from a long-spurred ancestor is linked to a loss of nectar production. This in turn is seemingly linked to a change in floral resource use by the main pollinators, from nectar feeding and pollen collection to exclusively pollen collection. Knowledge of plant-pollinator interactions are crucial for understanding ecosystem function and crop management. Given the current crises due the loss of biodiversity and pollinators LINARIA-SPECIATION can play a vital role at explaining pollination in an evolutionary context. It also provides important information for use in species conservation and ecosystem and crop management.
Keywords
Linaria, LINARIA-SPECIATION, pollinator, nectar spur, speciation