Whether viewed as a subfamily of Cricetidae or Muridae (Alston, 1876; Carleton and Musser, 1984; Ellerman, 1941; McKenna and Bell, 1997; Miller and Gidley, 1918; Musser and Carleton, 1993; Simpson, 1945; Thomas, 1896) or a separate family (Chaline et al., 1977; Pavlinov et al., 1990, 1995a; Reig, 1980; Wessels, 1998, 1999), species of gerbils form a distinct group defined by a suite of derived morphological traits. In a series of reports, Pavlinov (1980a, 1981a, b, 1982a, 1984b, 1985, 1986, 1987, 2001) presented analyses of skeletal, dental, and male genital characters of gerbils and developed a hypothesis of their phylogeny and a classification. The monograph by Pavlinov et al. (1990) represents a culmination of these efforts, in which the phylogeny, species classification, morphology, ecology, and geographical distribution of the genera and species in Gerbillinae are comprehensively reviewed. They recognized the family Gerbillidae, with two subfamilies. Taterillinae contains tribes Taterillini (Tatera, Taterillus, and Gerbilliscus) and Gerbillurini (Gerbillurus and Desmodillus). Gerbillinae is composed of Gerbillini (Dipodillus, Gerbillus, Monodia, and Microdillus), Desmodilliscini (Desmodilliscus), Pachyuromyini (Pachyuromys), and Rhombomyini (Sekeetamys, Meriones, Brachiones, Psammomys, and Rhombomys). Pavlinov et al. (1990) were uncertain about the subfamily allocation of Ammodillini (Ammodillus). An excellent short review of character distribution within gerbils that is the basis for the classification of Pavlinov et al. (1990) was provided by Pavlinov (2001). We observe their subfamilies as tribes and their tribes as subtribes.
Cytogenetic data for the subfamily summarized by Qumsiyeh and Schlitter (1991) and Viegas-Péquignot et al. (1986). Rates of protein, chromosomal, and morphological evolution in four genera reported by Qumsiyeh and Chesser (1988). Chromosomal and biochemical results of several species and genera documented and discussed in a phylogenetic context by Benazzou et al. (1982a, b, 1984) and Qumsiyeh (1986). Problems in using Robertsonian rearrangements to determine monophyly were elaborated by Qumsiyeh et al. (1987) using species of Gerbilliscus and Gerbillurus. Other chromosomal reports significant to gerbilline systematics are those by Gamperl and Vistorin (1980), Ratomponirina et al. (1986, 1989), and the references cited in the various species accounts below. Anatomy, physiology, adaptive significance, and evolution of the middle and inner ear of gerbillines documented by Lay (1972) and Pavlinov (1988, 2001); significance of acoustic emissions and morphology of cochlea in context of adaptation and systematics reported by Bridelance (1987) and Plassmann et al. (1987); the relationship of acoustical adaptations in relation to steppe and desert environments summarized by Petter et al. (1984); and significance of the relation between size of pinna and auditory bulla elaborated by Pavlinov and Rogovin (2000). Breed (1995d) described spermatozoal morphology of Gerbilliscus leucogaster and Gerbillurus paeba, regarded them as highly derived and unlike the spermatozoa of other muroid genera, but drew no phylogenetic inferences. Comparative study of male genital morphology of species in 12 genera and its taxonomic significance documented by Pavlinov (1986).
The origin and evolution of North African gerbils discussed by Tong (1989) whose results were presented in a phylogenetic classification of genera and compared with other classifications based on morphological, chromosomal, and biochemical data. Pavlinov (2001) contrasted Tong’s view with the classification by Pavlinov et al. (1990) and pointed out disagreements. Cockrum and Setzer (1976) reviewed holotypes and type localities associated with North African species. Palearctic species reviewed by Corbet (1978c, 1984); Russian species checklisted by Pavlinov and Rossolimo (1987) and reviewed by Gromov and Erbajeva (1995). Eurasian species listed by Pavlinov et al. (1995a). Zoogeography (patterns of geographic distributions, correlation with bioclimates, definition of faunal categories, and historical origin of the fauna) of Moroccan gerbils presented by Aulagnier (1991). Patterns of geographic variation in relative importance of gerbillines across the "Great Palaearctic Desert Belt" using biogeographic and ecological approaches reviewed and quantified by Shenbrot and Krasnov (2001).
Morphology clearly defines Gerbillinae (Carleton and Musser, 1984; Pavlinov et al., 1990). Molecular data does also, and indicates that phylogenetic affinities of gerbils are with murines and deomyines. Analyses of the nuclear protein-coding gene LCAT sequences (Michaux and Catzeflis, 2000), and LCAT in combination with sequences of the von Willebrand Factor (Michaux et al., 2001) placed gerbils as a sister-group with deomyines, in a clade also containing murines. This topography is also consistent with results of analyses of complete mtDNA cytochrome b (Martin et al., 2000) and nuclear IRBP sequences (Jansa and Weksler, 2004); the Murinae-Gerbillinae link was also revealed by analyses of DNA sequences from the nuclear genes GHR and BRCA1 (Adkins et al., 2003). From their molecular-clock estimate, Michaux et al. (2001) suggested the three families diverged 20.8-17.9 million years ago, with deomyines and gerbils separating 18.5-16.5 million years ago, events transpiring in the early Miocene. Such divergence times are not unreasonable in context of known evolutionary history of these groups. The earliest gerbil fossils come from the late Miocene of Eurasia and North Africa (Wessels, 1998), and those of its sister-group, the myocricetodontines, extend back to the early Miocene of Turkey, Pakistan, and Saudi Arabia, middle Miocene of China and Africa, and Late Miocene of Spain (Jaeger, 1977a,b; Lindsay, 1994; Qiu, 2001; Wessels, 1996, 1998, 1999). Current consensus suggests the Gerbillinae to have evolved from myocricetodontines (de Bruijn and Whybrow, 1994; Jaeger, 1977b; Lindsay, 1994; Tong, 1989; Wessels, 1998), whether viewed as a family containing Gerbillinae (Wessels, 1996), a subfamily by itself (Tong and Jaeger, 1993) or within Gerbillidae (Ameur-Chehbeur, 1991; Tong, 1989; Wessels, 1998, 1999), or a tribe within Gerbillinae (McKenna and Bell, 1997). Tong and Jaeger (1993) would also derive murines from an early ancestral myocricetodontine with the split between the two groups occurring 16 million years ago. The earliest deomyines are represented by fossils of Acomys from the early Pliocene (Denys, 1990b); earlier deomyines or fossils actually linking deomyines with gerbils have yet to be discovered.