Phylogeography, mitochondrial DNA diversity, and demographic history of geladas (Theropithecus gelada).

The large-bodied, terrestrial primates in the tribe Papionini are among the most intensely studied animals in the world, yet for some members of this tribe we know comparatively little about their evolutionary history and phylogeography. Geladas (Theropithecus gelada Rüppell, 1835), endemic primates of the Ethiopian highlands, are largely unstudied both in genetic diversity and intrageneric phylogeny. Currently, a northern and central subspecies and one isolated southern population are recognized, of which the central is classified as Least Concern, the northern as Vulnerable, and the southern is not yet assessed. The distribution and taxonomy of the subspecies remain poorly defined. Here, we estimate the mitochondrial DNA (mtDNA) diversity and phylogenetic relationships among gelada mtDNA lineages based on samples across the entire species range. We analysed 1.7 kb-long sequences of the mtDNA genome, spanning the cytochrome b gene and the hypervariable region I of the D-loop, derived from 162 faecal samples. We detected five major haplogroups or clades (south, central-1, central-2, north-1, north-2) which diverged between 0.67 and 0.43 million years ago, thus suggesting a rapid radiation, resulting in largely unresolved intrageneric phylogenetic relationships. Both, the northern and central demes contain two similarly valid haplogroups, each with little or no geographic segregation among respective haplogroups. Effective population sizes of the northern and central demes decreased during and after the last glacial maximum but remained stable for the southern deme, although on a very low level. The distribution of haplogroups within the geographic ranges of the putative gelada subspecies indicates that mtDNA sequence information does not allow reliable taxonomic inferences and thus is not sufficient for solving the taxonomic rank of the three demic populations, with the possible exception of the southern population. Nevertheless, due to the genetic differences all three populations deserve conservation efforts, in particular the smallest southern population.

The socio-genetics of a complex society: female gelada relatedness patterns mirror association patterns in a multilevel society.

Multilevel societies with fission-fusion dynamics--arguably the most complex animal societies--are defined by two or more nested levels of organization. The core of these societies are modular social units that regularly fission and fuse with one another. Despite convergent evolution in disparate taxa, we know strikingly little about how such societies form and how fitness benefits operate. Understanding the kinship structure of complex societies could inform us about the origins of the social structure as well as about the potential for individuals in these societies to accrue indirect fitness benefits. Here, we combined genetic and behavioural data on geladas (Theropithecus gelada), an Old World Monkey, to complete the most comprehensive socio-genetic analysis of a multilevel society to date. In geladas, individuals in the core social 'units', associate at different frequencies to form 'teams', 'bands' and, the largest aggregations, 'communities'. Units were composed of closely related females, and females remained with their close kin during permanent fissions of units. Interestingly, female-female relatedness also significantly predicted between-unit, between-team and between-band association patterns, while male-male relatedness did not. Thus, it is likely that the socio-genetic structure of gelada society results from females maintaining associations with their female relatives during successive unit fissions--possibly in an attempt to balance the direct and indirect fitness benefits of group living. Overall, the persistence of associations among related females across generations appears to drive the formation of higher levels of gelada society, suggesting that females seek kin for inclusive fitness benefits at multiple levels of gelada society.

Concessions of an alpha male? Cooperative defence and shared reproduction in multi-male primate groups.

By living in social groups with potential competitors, animals forgo monopolizing access to resources. Consequently, debate continues over how selection might favour sociality among competitors. For example, several models exist to account for the evolution of shared reproduction in groups. The 'concession model' hypothesizes that dominant reproducers benefit from the presence of subordinates, and hence tolerate some reproduction by subordinates. This mutual benefit to both dominants and subordinates may provide a foundation for the formation of social groups in which multiple members reproduce--a necessary step in the evolution of cooperation. To date, however, the concession model has received virtually no support in vertebrates. Instead, the vast majority of vertebrate data support 'limited control models', which posit that dominant reproducers are simply unable to prevent subordinates from reproducing. Here we present the most comprehensive evidence to date in support of the concession model in a vertebrate. We examined natural variation in the number of adult males in gelada (Theropithecus gelada) reproductive units to assess the extent of reproductive skew in multi-male units. Dominant ('leader') males in units that also had subordinate ('follower') males had a 30 per cent longer tenure than leaders in units that did not have followers, mainly because followers actively defended the group against potential immigrants. Follower males also obtained a small amount of reproduction in the unit, which may have functioned as a concession in return for defending the unit. These results suggest that dominants and subordinates may engage in mutually beneficial reproductive transactions, thus favouring male-male tolerance and cooperation.

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

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.

Introgressive hybridization in southern African baboons shapes patterns of mtDNA variation.

Species, as main evolutionary units have long been considered to be morphological entities with limited hybridization potential. The occurrence of taxa which maintain morphological distinctness despite extensive hybridization is an interesting phenomenon. To understand the evolution of these taxa, descriptions of contemporary morphological and genetic variation are essential, also to reconstruct sound phylogenies. Baboons, with their wide geographic range, variant morphotypes, and extensive hybridization offer an intriguing model for those studies. We focus on the complex situation in southern Africa that, in contrast to east Africa, has been neglected in terms of baboon hybridization history. We aim to clarify the distribution and identify possible overlapping zones between different, previously described mitochondrial (mt) DNA clades of baboons that do not match with the ranges of traditionally recognized species. On the basis of the widespread sampling and mitochondrial cytochrome b gene sequencing, we constructed a phylogenetic tree that separates representatives of the two southern African baboon species, yellow and chacma baboons, into six clades: southern, northern and eastern chacmas, Kinda baboons and southern and Luangwa yellow baboons. The ranges of the chacma clades come into close contact or overlap in two regions in the Republic of South Africa and Namibia. Our phylogenetic reconstruction reveals mitochondrial paraphyly for chacma and yellow baboons, which is probably caused by introgressive hybridization and subsequent nuclear swamping, whereby males of the chacma morphotype population from the south invaded the yellow morphotype population in the north bringing their morphotype into a population that maintained its yellow baboon mtDNA.

Morphometric variation in the papionin muzzle and the biochronology of the South African Plio-Pleistocene karst cave deposits.

Papionin monkeys are widespread, relatively common members of Plio-Pleistocene faunal assemblages across Africa. For these reasons, papionin taxa have been used as biochronological indicators by which to infer the ages of the South African karst cave deposits. A recent morphometric study of South African fossil papionin muzzle shape concluded that its variation attests to a substantial and greater time depth for these sites than is generally estimated. This inference is significant, because accurate dating of the South African cave sites is critical to our knowledge of hominin evolution and mammalian biogeographic history. We here report the results of a comparative analysis of extant papionin monkeys by which variability of the South African fossil papionins may be assessed. The muzzles of 106 specimens representing six extant papionin genera were digitized and interlandmark distances were calculated. Results demonstrate that the overall amount of morphological variation present within the fossil assemblage fits comfortably within the range exhibited by the extant sample. We also performed a statistical experiment to assess the limitations imposed by small sample sizes, such as typically encountered in the fossil record. Results suggest that 15 specimens are sufficient to accurately represent the population mean for a given phenotype, but small sample sizes are insufficient to permit the accurate estimation of the population standard deviation, variance, and range. The suggestion that the muzzle morphology of fossil papionins attests to a considerable and previously unrecognized temporal depth of the South African karst cave sites is unwarranted.

Mitochondrial DNA phylogeny of the Old-World monkey tribe Papionini.

The evolution of the Old World monkey tribe Papionini, composed of macaques, baboons, mandrills, drills, and mangabeys, was examined using mitochondrial DNA (mtDNA) sequence data on the cytochrome oxidase subunit II gene. When analyzed cladistically, these data support a baboon clade of savannah (Papio) plus gelada (Theropithecus) baboons, as well as a clade containing drill (Mandrillus) plus mangabey (Cerocebus) genera. This result stands in opposition to most morphological phylogenies, which break up the baboon clade by placing Papio and Mandrillus as sister taxa and Theropithecus as a more distantly related lineage. Analyses of COII gene sequences also suggest that the papionin ancestral stock divided into two lineages, one leading to macaques and the other to the purely African genera. From a molecular evolutionary perspective, the papionin COII gene sequences reveal a pattern of amino acid replacements concentrated in the regions spanning the mitochondrial membrane.

Fibrinopeptides A and B of baboons (Papio anubis, Papio hamadryas, and Theropithecus gelada): their amino acid sequences and evolutionary rates and a molecular phylogeny for the baboons.

Amino acid sequences of fibrinopeptides A and B from savanna baboons, Papio anubis and Papio hamadryas, and highland baboon, Theropithecus gelada, were established. The sequences of the fibrinopeptides A from the three baboons were identical: (sequence: see text) The fibrinopeptides B were composed of 9 residues and demonstrated the sequence: (sequence see text) where X3 = Arg in P. anubis, His in P. hamadryas, and Gly in Th. gelada. Position-3 of the B peptides was the only replacement site observed among the 25 amino acid residues in both fibrinopeptides from the baboons. Based on these sequences, a molecular phylogeny for the three species of baboons was deduced. The evolutionary rates of the peptides B of the baboons and macaques were also estimated. It was observed that the fibrinopeptides changed at an uneven rate during the evolution of old-world monkeys, i.e., baboons and macaques.