Population differentiation
Microevolutionary processes could be an alternative explanation for the
colonization history of L. columnaris in the Afromontane sky
islands of West Central Africa. The early split in L. columnarispopulations between the mainland and South Bioko possibly occurred via a
founder event and genetic bottleneck or subsequent genetic drift so that
South Bioko plastomes are very distinct relative to the other plastome
groups. Furthermore, the two early splits (Figure 3) suggest two
independent colonization events of L. columnaris on the island.
Under this scenario, the colonization history was likely from mainland
Cameroon’s old sky islands to the southern young sky islands in Bioko.
This explanation should be developed with population genetic analyses to
explore the correlation between geographic distance and genetic
differentiation of populations and find which evolutionary forces are
responsible for population differentiation in Bioko.