Differences in the genetic basis of leaf dissection between two populations of Crepis tectorum (Asteraceae)

Abstract

In the present investigation, I compare the genetic basis of the dissected leaves characterizing two populations of the annual plant Crepis tectorum in the Baltic region, one on the island of Öland (SE Sweden) and the other in the district of Åland (S Finland). Patterns of segregation in crosses using the same simple-leaved plant as a seed parent demonstrate that finely dissected leaves are completely dominant over weakly lobed leaves, that a single major gene may be responsible for the deeply lobed leaves of the Öland population and that three, perhaps four, major genes control leaf dissection in the Åland population. Different dominant genes may be responsible for leaf dissection in the Åland and Öland populations, as shown by the presence of an entire-leaved plant in the F₂ progeny of a cross between these populations. These results lend further support to the hypothesis that few genetic changes were involved in the shift from weakly to deeply lobed leaves. Field data from the öland population indicate low penetrance of the single major gene segregating in crosses with simple-leaved populations.