Isolated intermediates - products of long distance gene dispersal, phantom hybridity or convergent evolution? The case of the half-barked Eucalyptus amygdalina

Abstract

Apparent intermediates between Eucalyptus amygdalina and E. pulchella occur well outside the recognized range of the latter species. Progenies of these isolated intermediates were grown in uniform conditions with progenies of trees of E. pulchella, E. amygdaline and apparent hybrids between these two species that are found where they occur parapatrically. The isolated intermediate population proved identical with E. amygdalina in seedling characteristics, while the parapatric intermediates were more variable than the other populations, this variability probably being partly the result of hybridization between E. amygdalina and either E. tenuiramis or E. risdonii. The allopatric intermediate population is more likely to have resulted from convergence of E. amygdalina in the direction of E. pulchella than from phantom hybridity or long distance gene migration.