Australian Mistletoe‐Host Leaf Resemblance: Support for Eco‐Physiological Convergence Rather Than Disperser‐ or Herbivore‐Driven Mimicry

Presently, there are three main hypotheses to explain why the leaves of many Australian mistletoes resemble their hosts. The eco‐physiological convergence hypothesis suggests that mistletoes must manage their physiology, especially their water relations, to match those of the host, to avoid killing themselves or the host branch they have parasitised. This could be achieved by having similar leaves to the host. The anti‐herbivore mimicry hypothesis suggests that when mistletoes are more palatable than their hosts, they may suffer less herbivory if they mimic their host. This would be protective crypsis if the herbivore mistakes the mistletoe leaf for a less palatable host leaf and avoids these leaves. The disperser mimicry hypothesis suggests that host resemblance may increase dispersal to preferred hosts if birds used mistletoe foliage, rather than fruit, to find further mistletoes. Presently, there are both logical and empirical problems with the mimicry hypotheses and some weak support for the convergence hypothesis.