Details

Autor(en) / Beteiligte

• Wootton, J. Timothy
• I-Fang Sun

Titel

Bract liquid as a herbivore defense mechanism for Heliconia wagneriana inflorescences

Ist Teil von

• Biotropica, 1990-06, Vol.22 (2), p.155-159

Ort / Verlag

Malden, MA: Association for Tropical Biology

Erscheinungsjahr

1990

Beschreibungen/Notizen

• The evolution of inflorescence morphology is usually considered to have been shaped by natural selection to enhance the chances of pollination or control gene flow. However, herbivores can affect plant fitness by damaging seeds and reproductive parts, or by nectar robbing, which reduces the chances of pollination. Tank species of Heliconia have inflorescences characterized by enlarged bracts that hold many flowers partially submerged in a large volume of liquid. Experiments in which we removed bract liquid and bagged flowers from H. wagneriana demonstrated that these plants actively secreted bract liquid. Rates of bract liquid secretion differed between individuals, and did not correlate with three environmental factors: rainfall, number of leaves, or number of bracts. By making drain holes in inflorescences of H. wagneriana, we tested whether bract liquid served as a herbivore defense. Compared to experimentally drained inflorescences and inflorescences of a second species which does not have bract liquid (H. pogonantha), liquid in control inflorescences substantially depressed the rates of herbivory on ovaries and other reproductive structures, and reduced the incidence of nectar robbing by chewing insects. The results suggest that bract liquid and its associated maintenance structures in the inflorescences of tank Heliconia defend the reproductive structures from herbivory, and that herbivory may generally play a role in shaping the evolution of floral morphology.