Do positions in individual-based ectoparasite-small mammal networks differ between female and male hosts?

Abstract

We investigated the contributions of female and male hosts to the structure of individual-based host-parasite networks, using 21 species of small mammals from two regions (West Siberia and eastern Slovakia) and two taxa of ectoparasitic arthropods (fleas and gamasid mites). We asked whether (a) the values of individual host position indices (individual strength, nested rank, the degree of individual specialization, and the eigenvector centrality) and individual host roles differed between female and male hosts in each network and (if yes) were associated with differences in the infestation levels, (b) differences between sexes (if any) were further translated into differences in the network structure (nestedness and network specificity), and (c) differences between female and male hosts in their positions and roles and the effect of these differences on the network structure differed between host-flea and host-mite networks. In the majority of individual-based host-ectoparasite networks, female and male hosts differed in their positions despite a general lack of differences in the infestation levels. The distribution of the roles played in a network mostly did not differ between sexes. The extent of position differences between sexes affected the structure of host-flea, but not host-mite, networks in terms of the network specificity. In addition, the occurrence and the direction of these differences (i.e., the greater value of the position index in either female or male hosts) often varied (a) between host-flea and host-mite networks in the same host, (b) between host species within host-flea and host-mite networks, and (c) between the two regions in the same host-flea or host-mite network. We conclude that differences in the positions of male and female hosts in individual-based host-parasite networks are mediated by host biology, parasite biology, and environmental factors.