Conclusions
The plastome analysis provided an informative phylogenetic
reconstruction but partial colonization reconstruction of Lobelia
columnaris . Overall, three groups are in West-Central Africa.
According to our phylogenomic calibration, the ancestor of L.
columnaris arrived in West Central Africa (ca. 1.5 Ma) during the
Cameroon line’s youngest volcanoes’ uplift. The Pleistocene climatic
oscillations led to the divergence of the Cameroon and Bioko populations
into three clades. Likely, South Bioko was forest refugia during the
interglacial periods. Here, we show that the biogeographic history ofL. columnaris does not follow the progression of ages of our sky
islands.
In more recent times, Bioko’s central depression likely functions as a
geographic barrier to further isolate the population groups discovered
in our analysis (South Bioko versus North Bioko-Cameroon). Moreover,
grazing, burning, and deforestation are threatening Afromontane forest
patches with L. columnaris in mainland Cameroon.
Data accessibility We are working the data storage from the
plastomes generated in this study. Data will be deposited in GeneBank