Isolation of microsatellite loci in Akodon azarae (Muridae, Sigmodontinae) and cross-amplification in other Akodontini species

Abstract

Fragmentation of natural habitats is an increasing problem worldwide, having profound consequences on the genetic and demographic structure of natural populations (Mech and Hallet 2001). A representative example of a fragmentation process occurs in central Argentina, an area of approximately 500,000 km2 formerly occupied by prairies, but currently consisting almost exclusively of crops and livestock pastures separated by fencelines, roads and railroads, along which native and introduced weeds grow: the ‘border’ habitats. One of the most important components of the fauna in this region are rodents of the subfamily Sigmodontinae, a highly speciose group of mostly South American distribution, assembled in seven different tribes (Reig 1984). Three of the most abundant Sigmodontine species in agroecosystems of central Argentina are Calomys musculinus and C. venustus (tribe Phyllotini), and Akodon azarae, pertaining to the tribe Akodontini, the second most important according to the number of species (Reig 1984). Previous studies have established that these species differ in several ecological and behavioural characteristics like habitat use (A. azarae and C. venustus preferentially use borders while C. musculinus inhabits both borders and crop fields; Mills et al. 1992; Polop and Sabattini 1993; Busch et al. 1997), space use (home range size vary by sex and breeding period in A. azarae and C. musculinus, and by population abundance in C. venustus; Priotto and Steinmann 1999; Priotto et al. 2002), mating system (promiscuous/polygynous in C. venustus and A. azarae and promiscuous in C. musculinus; Priotto and Steinmann