Rare, but steady, introgression in Austrian black poplar as a long-term risk : Genetic diversity in river populations of European Black Poplar

Budapest

2002

Bandaufführung

9452S

95586

Several years back (Heinze 1998a), we have analysed possible introgression of hybrid poplar genes into the native Austrian gene pool of black poplar (Populus nigra). Hybrid clones, mainly P. deltoides x P. nigra (=P. x euramericana), have been introduced to Austria since around 1860. They replaced native stands of P. nigra gradually, and now, only few large natural stands of black poplar are left (Heinze 1998b). Simple DNA markers have been developed and employed in the introgression study. We were specifically targeting areas where remnant populations or trees of black poplar occur side-by-side with hybrid clones. We ssupplemented the molecular marker studies with flowering time observations, in order to check whether flowering periods would overlap sufficiently between native and hybrid poplars. A few cases of introgression were detected, but at best, this comes down to an estimate of up to 5% of introgression in one generation. What are the possible reasons and consequences of that situation in the long term?