Wallace Helen Margaret, Leonhardt Sara Diana
Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC 4558, Australia.
Department of Animal Ecology and Tropical Biology, University of Würzburg, 97074, Würzburg, Germany.
PLoS One. 2015 Sep 29;10(9):e0138868. doi: 10.1371/journal.pone.0138868. eCollection 2015.
Tree invasions have substantial impacts on biodiversity and ecosystem functioning, and trees that are dispersed by animals are more likely to become invasive. In addition, hybridisation between plants is well documented as a source of new weeds, as hybrids gain new characteristics that allow them to become invasive. Corymbia torelliana is an invasive tree with an unusual animal dispersal mechanism: seed dispersal by stingless bees, that hybridizes readily with other species. We examined hybrids between C. torelliana and C. citriodora subsp. citriodora to determine whether hybrids have inherited the seed dispersal characteristics of C. torelliana that allow bee dispersal. Some hybrid fruits displayed the characteristic hollowness, resin production and resin chemistry associated with seed dispersal by bees. However, we did not observe bees foraging on any hybrid fruits until they had been damaged. We conclude that C. torelliana and C. citriodora subsp. citriodora hybrids can inherit some fruit characters that are associated with dispersal by bees, but we did not find a hybrid with the complete set of characters that would enable bee dispersal. However, around 20,000 hybrids have been planted in Australia, and ongoing monitoring is necessary to identify any hybrids that may become invasive.
树木入侵对生物多样性和生态系统功能有重大影响，而通过动物传播的树木更有可能成为入侵物种。此外，植物间的杂交作为新杂草的一个来源已有充分记载，因为杂交种获得了使其能够成为入侵物种的新特性。托雷桉是一种具有不寻常动物传播机制的入侵树种：由无刺蜂传播种子，且容易与其他物种杂交。我们研究了托雷桉与柠檬桉亚种柠檬桉之间的杂交种，以确定杂交种是否继承了托雷桉能让蜜蜂传播种子的特性。一些杂交果实呈现出与蜜蜂传播种子相关的中空、树脂分泌和树脂化学成分等特征。然而，在杂交果实受损之前，我们未观察到蜜蜂取食任何杂交果实。我们得出结论，托雷桉与柠檬桉亚种柠檬桉的杂交种可以继承一些与蜜蜂传播相关的果实特征，但我们未发现具有能实现蜜蜂传播的全套特征的杂交种。然而，澳大利亚已种植了约2万株杂交种，因此有必要持续监测以识别任何可能成为入侵物种的杂交种。
