%0 Journal Article %T Rossomyrmex, the Slave-Maker Ants from the Arid Steppe Environments %A F. Ruano %A O. Sanllorente %A A. Lenoir %A A. Tinaut %J Psyche %D 2013 %I Hindawi Publishing Corporation %R 10.1155/2013/541804 %X The host-parasite genera Proformica-Rossomyrmex present four pairs of species with a very wide range of distribution from China to Southeastern Spain, from huge extended plains to the top of high mountains. Here we review (1) the published data on these pairs in comparison to other slave-makers; (2) the different dispersal ability in hosts and parasites inferred from genetics (chance of migration conditions the evolutionary potential of the species); (3) the evolutionary potential of host and parasite determining the coevolutionary process in each host-parasite system that we treat to define using cuticular chemical data. We find a lower evolutionary potential in parasites than in hosts in fragmented populations, where selective pressures give advantage to a limited female parasite migration due to uncertainty of locating a host nest. A similar evolutionary potential is detected for hosts and parasites when the finding of host nests is likely (i.e., in continuous and extended populations). Moreover, some level of local adaptation at CHC profiles between host and parasite exists independently of the kind of geographic distribution and the ability of dispersal of the different populations. Similarity at CHC profiles appears to be a trait imposed by natural selection for the interaction between hosts and slave-makers. 1. Introduction Slave-making ants are a type of permanent social parasites (thus depending on enslaved hosts ants throughout their whole live) whose newly mated queens need to usurp a host nest in order to initiate a new parasite colony. Then the host brood will turn into slaves working for the parasite species while parasite workers only concentrate on replenishing the labour force from neighboring host nests, a process called slave raiding (see reviews [1¨C4]). The slave-maker style of life imposes selection pressures to both parts, as frequent slave raids strongly affect host populations and on the other hand, invading a host nest by parasite queens is determinant for their survival (see [2, 5, 6]). In this sense the study of host-parasite systems allows the study of coevolutionary strategies. Within the subfamily Formicinae only two genera fit the previous definition of slave-makers: Polyergus and Rossomyrmex [5¨C7]. The species of the Formica sanguinea group are facultative slave-makers [8, 9]. Thus, in relation with the obligate slave-maker genera most of the published studies are focused on Polyergus biology (e.g., [10¨C15]) whereas the genus Rossomyrmex has received little attention, probably due to its geographic distribution and %U http://www.hindawi.com/journals/psyche/2013/541804/