Structure and evolution of co-authorship network in an interdisciplinary research field

The structure and evolution of co-authorship networks have been extensively studied in literature. However, the studies on the co-authorship network in a specific interdisciplinary field may be complementary to the mainstream of existing works. In this paper, the interdisciplinary field of "evolution of cooperation", which has been prevalent in the last decades as a promising scientific frontier, is analyzed by extracting its co-authorship network mainly from Web of Science. The results show that the development of this field is characterized by the growth of a giant component of its collaboration network. Originally formed by assembling a few local clusters, the giant component has gradually evolved from a small cluster to a structure of "chained-communities", and then to a small-world structure. Through examining the degree distributions and analyzing the vulnerability, we uncover that the giant component is comprised of the "elite", the "middle-class" and the "grassroots", with respect to the nodes' degrees and their functions in structuring the giant component. Furthermore, the elite and the middle-class constitute a robust cohesive-core, which underpins the modular network of the giant component. The overall results of this work may illuminate more endeavors on the collaboration network in other interdisciplinary fields.