g. Fewell & Page Jr, 1999; Helms Cahan & Fewell, 2004; Jeanson & Fewell, 2008). To investigate emergence of reproductive division of labor, we quantified the allocation of reproduction between Selleckchem Belnacasan two queens when forced to cofound a nest, and compared the extent of division of labor in reproduction to that of nest excavation, a nonreproductive behavior previously

shown to emerge spontaneously in forced associations (Fewell & Page Jr, 1999). To investigate how division of labor in these two tasks might be generated mechanistically, we tested whether task specialists could be predicted by their relative size, aggressive behavior or performance of other tasks. The harvester ant P. barbatus is a large-bodied granivore whose range extends from central Mexico to southeast Arizona in the west and south-central Texas to the east

(Johnson, 2000). All North American species in this genus are exclusively solitary founding with the exception of a single group-founding population of the desert specialist P. californicus, MK-8669 distantly related to P. barbatus (Parker & Rissing, 2002; Helms Cahan & Fewell, 2004). Colonies reproduce after monsoon rains in mid-summer by releasing large numbers of winged males and virgin queens that congregate in dense mating swarms. Following mating, queens disperse aerially from the mating swarm site, remove their wings and begin to excavate an incipient nest in the soil. When the nest is complete, the queen

seals the entrance from the inside and begins egg-laying and brood care. Queens do not forage during this period and feed the brood from excess eggs and other secretions derived from the queen’s muscle and fat reserves. Depending on 上海皓元 the temperature, the first workers emerge in 6–8 weeks, open the nest and assume all nonreproductive tasks. Experiments were conducted over 2 years: 90 newly mated queens were collected on the ground following a mating flight in Hidalgo Co., New Mexico, on 27 July 2011, and 108 were collected from a similar mating flight in Santa Cruz Co., Arizona on 7 July 2012. These populations contain two distinct genetic lineages, referred to as J1 and J2, and produce workers solely from interlineage crosses (genetic caste determination, Julian et al., 2002; Volny & Gordon, 2002a). The two lineages can be distinguished genetically (Helms Cahan & Keller, 2003; Schwander, Helms Cahan & Keller, 2006) but not visually or behaviorally, and queens were paired without regard to their lineage identity. Although previous studies have found productivity differences between lineages due to differences in fecundity and/or sperm stores (Anderson et al., 2006, 2011; Helms Cahan et al., 2010), comparison of the reproductive output of J1 and J2 queens kept alone in this study revealed no differences in intrinsic productivity between lineages (t26 = 1.62, P = 0.