Theropithecus gelada distribution and variations related to taxonomy: history, challenges and implications for conservation

Abstract

Despite the uniqueness and importance of Theropithecus in palaeontological studies, little is known about the geographical and taxonomic differentiation in this genus, now restricted to the Ethiopian Highlands. Traditionally, the single living species Theropithecus gelada (Rüppell 1835) has been considered to comprise two subspecies: the nominate T. g. gelada in the northern highlands, and T. g. obscurus Heuglin 1863, from latitude 12 degrees to 9 degrees N in the south. Both the distributions and the physical characters of these two subspecies are poorly defined, and even in recent major taxonomic revisions, the validity of T. g. obscurus has been questioned. The history of gelada taxonomy and museum collections is reviewed here, and results are compared with the biogeography and major physical features of the Ethiopian Highlands. It is concluded that major gaps exist in our knowledge of the differentiation and distributions of Theropithecus populations. Following this literature review, a series of priority regions for taxonomic research and conservation are identified. These include the gathering of data on (1) geladas inhabiting the Wollo Region, from where obscurus was originally described; (2) the identity of geladas of the Tigray Region northeast of the Tacazzé River, and their current conservation status; (3) the identity of the Shewa population, usually assigned to obscurus; and (4) the identity and current status of geladas found northeast and south of Lake Tana, including Gojjam.

Genetic diversity within and among gelada (<i>Theropithecus gelada</i>) populations based on mitochondrial DNA analysis

“…This chain is a watershed of the Bishlo, Wonchit, and Weiqua rivers but has no cliffs. This region is probably the blank area of the distribution that was indicated by Yalden and Largen (1992) and Gippoliti (2010). This geological condition may be an isolation factor that contributed to the subdivision of the populations of the Jemma or Wonchit rivers located to the south.…”

“…The classification of T. gelada gelada and T. g. obscurus is under debate (Yalden and Largen, 1992;Yalden et al, 1996;Gippoliti, 2010). According to our observations, the boundary between these subspecies is the central tableland, crossed by the road from Wereta to Weldya, on the northern plateau (a watershed of the Takazze and Blue Nile rivers, with Mount Guna, 4275 m high, on the west).…”

“…A subspecies was later documented by Heuglin (1863). Geladas from the northern (north of Lake Tana and west of the Takazze river) and southern regions (south of Lake Tana and east of the Takazze river) are believed to be T. gelada gelada and T. gelada obscurus, respectively; however, a clear distinction between them has not yet been determined (Yalden et al, 1977(Yalden et al, , 1996Gippoliti, 2010). Several studies have detailed the natural history of this species (Jolly, 1972;Delson, 1993;Jablonski, 1993).…”

“…However, Groves (1972) had previously assumed that some geladas were present in this area and named this virtual subspecies senex (Yalden et al, 1977;Mittermeier et al, 2013). Gippoliti (2010) pointed out that the subspecies name 'senex' is nonsense because it is already a junior synonym of gelada. Iwamoto et al (1996) and Mori et al (1997Mori et al ( , 1999Mori et al ( , 2003 later conducted detailed studies on the social and ecological behaviors of this group and documented differences in social structures, behaviors, and fur coloration, as compared with geladas on the northern pla-Genetic diversity within and among gelada (Theropithecus gelada) populations based on mitochondrial DNA analysis (Nei, 1972) between the groups, and suggested the third subspecies.…”

“…Belay and Mori (2006) suggested, on the basis of a preliminary mitochondrial DNA (mtDNA) analysis, that the Arsi gelada is a distinct subspecies. Gippoliti (2010) described ambiguities in the current classifications and distributions of geladas and emphasized that detailed surveys and studies are required for conservation of geladas.…”