Before revision:  The structural complexities of the underlying population, such as Newman-Watts small world networks, Erdo s-R\'enyi random networks, and Barab\'asi-Albert networks, also do not alter the working of the dynamical reciprocity.
After revision:  The structural complexities of the underlying population, such as Newman-Watts small world networks, Erdo s-R\'enyi random networks, and Barab\'asi--Albert networks, also do not alter the working of the dynamical reciprocity.