Host eyes, brains and their brood parasites
- Anders Møller,
- Johannes Erritzøe
Abstract
1. Brood parasites interact with their hosts for exploitation of host
parental abilities and the associated resources. This results in
coevolutionary interactions of hosts and parasites. 2. A prime example
of such a common specialist brood parasite is the common cuckoo Cuculus
canorus and its host races. Hosts use their cognitive abilities to
identify parasites and vice versa for their ability to discriminate
among potential hosts. 3. We predicted that parasites with relatively
large brains for their body size should be more successful at avoiding
their hosts, and that hosts with small brains for their body size should
more often be exploited by parasites. We also predicted that hosts with
relatively large eyes for their body size would have superior
discriminatory abilities allowing for superior discrimination against
brood parasites. Finally, we predicted that visual ability of specific
cuckoo hosts would have evolved exaggerated visual ability as estimated
from the relative size of their optic tectum would have resulted in such
hosts being more successful as reflected by their higher rate of
parasitism. 4. Interspecific variation in size of brain, eye, optic
tectum, telencephalon and cerebellum were consistent with these
predictions.