The Oxidative Cost of Unstable Social Dominance - Essay Example

Mandrill Primates are magnificently diverse species having varied taxonomy, lifestyle, and geographical range. Among those primates, Mandrills are known to be the most exotic as well as distinct ones, and are the prominent subject in many African legends. The word ‘Mandrill’ means ‘man-ape’ and they belong to the non-Apes category among the primates of “Old World monkeys”. They are the largest species of the monkeys in the world and are considered to be a vulnerable and threatened species in the contemporary ecological scenario. These reclusive primates are natively found living in the tropical rainforests of equatorial West Africa. The discussion typically focuses on the Mandrill sphinx, the mandrill species, which posses unique social characteristics, physical appearances, and behavior traits. The physical and behavioral traits of mandrill are particularly explored. The discussion also explains in depth the Class, Family, Order, and taxonomy of the species along with its biological description and habitat facts. The social behavior and reproduction facts of these species are also explained in detail. The systematic classification of this species provides an in-depth knowledge about the animal and its phylogeny. As per the taxonomy, animals are typically classified as Kingdom, Phylum, Class, Order, Family, Genus, and Species. Mandrill come under the Kingdom Animalia; Phylum Chordata; Subphylum Vertebrata; and Class Mammalia (Gron, 2009). They belong to the biological Order Primates, and typically come under the Suborder Catarrhini, which comprises of apes and the Old World monkeys. Mandrill is considered to be an Old World monkey, characterized by its long limbs, larger size, upright tail, and light colored fur. They are further classified under the superfamily Cercopithecoidea, which consists of the Old World monkeys, as well as is a part of the family of Cercopithecidae and the subfamily of Cercopithecinae, consisting of baboons, macaques, mangabeys, and other relatives. Mandrill or Mandrillus sphinx is a largest primate belonging to the Papionini tribe and comes under the genus of Mandrillus, which includes both drills and mandrills. There are no subspecies under this category and so are referred with their common name, instead of scientific name. Mandrills are found in and around the dense tropical rainforest as well as in the grasslands of southern Cameroon, Equatorial Guinea, Gabon, and Congo in the western-central parts of Africa. The geographical range of these mandrills is bordered between the Sanaga River in the north and the Ivindoand Ogooué rivers in the east. Certain researches suggest that there are some genetically observed differences between the mandrill species in the north and south of Ogooué River. Moreover, the habitat of mandrills typically belongs to the tropical forests, including Montane secondary forests and thick bushes. “M. sphinx inhabits mainly tropical rain forests (including semi-deciduous lowland rainforest, closed-canopy lowland moist forest, and other primary and secondary rainforests often with very dense vegetation) and forest-savannah mosaic forests” (Gron, 2009). Mandrills are Old World monkeys that are closely related to baboons and even more to drills at some varying extents. Though they were once thought to be a sub-category of baboons, further studies determined enough differences between the two classes, putting them as a different category. One of the unique physical traits of mandrills is their distinctive colors. These species are extremely colorful and has a thick dark grey pelage, marked with strips of black and reddish-yellow. It has a bright colored orangish beard on its hairless face, which provides it with a profound difference when compared with the other species in this genus. Mandrill features an elongated snout with swollen blue ridges on top along with red nose and lips. The colors of the Mandrills turn brighter when they get excited and it is also an indication of their sexual maturity. A mature mandrill is identified with the red and blue facial blends and brightly hued rumps. “A mandrills face has a red stripe down the middle of the muzzle and around the nostrils, while the sides of the muzzle are ridged lengthwise and colored blue” (Ingmarsson, 1999). An average Mandrill reaches up to 80 cm of height and is identified as large-bodied primates with a huge head, powerful limbs, and a stubby tail. They also have extremely long canines for self-defense, though sometimes used as a typical friendly gesture among the “troops” of Mandrills. Their wide rotating clavicles enable them in climbing trees while the opposable thumbs helps grasping tree branches. Mandrills are primarily terrestrial and move around the forest quadrupedally, with their long arms foraging the ground for food. Even though they have adapted to living on the ground, they take shelter on the trees during nights and take refuge in the foliage when chased. They also make lateral jumps at the height of 2 to 5 meters range from the ground level. Mandrills are frugivorous in nature but also eat seeds, leaves, shoots, nuts, arthropods, crabs, fish, small insects and vertebrates, as well as cultivated crops like manioc, bananas, avocados, or oil-palm fruits. They prefer to forage the gallery forests and savannas during the dry season, when the continuous forest is depleted of its fruit resources. “In Cameroon the diet of the mandrill was found to be composed of 84% fruit, 6% leaves, 7.6% animals, 1% mushrooms, 1% soils, and 0.3% other” (“Mandrill,” 2007). Mandrills have large cheeks with built-in pouches that stores food for later consumption. These pouches are beside their lower teeth and extend down the sides of their neck. “When competing for food or foraging in a dangerous place, mandrills can quickly cram food into the cheek pouches then retreat to a safe place to eat” (“Mandrill,” n. d). Moreover, the physical feature of the animal is endothermic and homoiothermic, possessing a relatively high body temperature. Mandrills usually have a lifespan of 46 years. Mandrills’ social behavior is extremely gregarious in nature and is often attributed to their group structure. Socialization among mandrills forms a part of their lifestyle. “The mandrills live in a large and stable group called a “horde” or “troop”, a lifestyle in which socialization plays a huge role. Large groups with as many as 800 members have stayed together year after year, foraging for food, breeding, and fighting” (“The Masked Mandrill,” 2013). Mandrills living as troops are headed by a dominant male, who is huge and brightly colored. The troops normally exhibit a strict hierarchy. Another typical social group of Mandrills is headed by the dominant male who mates with fertile females, fathering almost all the infants thereby forming a harem-like structure. This kind of polygyny group consists of around 15 individuals, including a dozens of females and young ones with one huge male. However, there are large groups of Mandrills as well, with each group having hundreds of Mandrills together gathering in multi-male or multi-female groups, sometimes ranging around 200 individuals. Mandrill groups are noisy as they communicate with deep grunts and high pitched crowing. “Females vocalize frequently, using a complex repertoire of calls. Most obvious are long, shrill ‘wraaaaahh’ screams, used to maintain contact across large group spreads” (Kingdon et al., 2013, p.195). Moreover, there are also other contact calls such as chuckling and burbling which are not so loud but used occasionally to maintain group cohesion during foraging. One of the typical behaviors of Mandrills is their dominance and aggressive attitude within and towards other groups. As Mandrills live in hierarchically structured groups, younger adolescent Mandrills develop an aggressive behavior when interacting with virtually every group, especially the adult males. This is because of the unstable social grouping among males as they disperse regularly from group to group. On the other hand, females are stable and maternally inherited within a group, owing to their behavior of staying together with their matrilineal group throughout life. The younger males’ aggressive nature exacerbate during the mating season, as they want to compete and establish their dominance with the females of the group. However, adult males exert lesser aggressive behavior because of their protective responsibility for the group or harem. Perhaps, the older adolescent Mandrills are the dangerous ones, exhibiting unrivaled strength and aggression towards other Mandrills. The reason for such behavior among adolescent Mandrills is to gain acceptance and compete in dominating the other group members. The intra-sexual competition and changes in male hierarchy leads to ferocious inter-male competitions among the adolescent Mandrills for reproduction and group dominance. “Male adolescents vie for dominance, and gain the respect of fellowgroup members through aggressive behavior” (Schwartz, 2006, p.8). Mandrills are considered to possess the most prominent sexual dimorphism among all primates. Comparatively in size, males are much larger than females, and this spectacular appearance is used for announcing its virility to the females. Males weigh an average of 25 to 35 kg while females is just less than half of that around 11-14kg. Similarly, the height of an average male is around 81-90 cm and the female being 56-66 cm (Schwartz, 2006). Male Mandrills have multi-colored anogenital areas and all Mandrills, irrespective of sexes, have a pale pink ischial callosities (Schwartz, 2006). Additionally, males have longer canines than the females approximately, 4.5 cm when compared to the 1.0 cm in females. Males have a prominent hair growth, measuring up to 6.5cm long around the canine tooth and nostrils, which is used as a means to threaten predators. The sexual dimorphism among Mandrills extends beyond the size and weight difference. Perhaps, the color of the animal holds a unique differentiating feature as the face of a male has striking colors while the female has a more subdued coloration ranging from black to bright pink. Bright color starts to appear on the male particularly during puberty. Moreover, the brightness of these colors in male Mandrills correlates to their dominance level in the groups. Also, sexual attractions are attributed to their colors as females tend to prefer brighter colored males. The ornamentation by colors in Mandrills during their mating season is common among male Mandrills and this correlates to their competition potential and ranking level within their groups. “High-ranking male Mandrills develop spectacular colored skin ornaments during the mating season (e.g. red face, mauve rump, red penis), while low-ranking male Mandrills are arrested in their capacity to exhibit such physical features” (Beaulieu et al., 2014). The reproductive behavior in Mandrills is polygamous. Though there is no particular breeding season among Mandrills, breeding occurs among individual females once in every two years. The Mandrills mate during the estrus cycle that occurs every 33 days. Female Mandrills have a prominent estrus swelling that identifies the receptive period of their reproductive status. The gestation period lasts for 6 to 7 months and the females give birth to only one offspring at a time. The infants are born with pink skin and black coat of fur. Initially, the female Mandrills wean the infants by carrying them ventrally for 3 to 5 months and then taking care of them until they are fully independent and mature. Males do not play any role in infant care, but sometimes the juvenile males carry infants in the wild acting as breeding ‘helpers’ but this behavior is quite rare among Mandrills. Male Mandrills reach their maturity in about three years while females take four or five years. When young female Mandrills reach maturity, they live within the groups, while the males leave the groups and return only during the mating season. Mandrills are categorized as vulnerable species by International Union for the Conservation of Nature (IUCN). Though physically Mandrills are large mammals and have very few natural predators, the most immediate threat is posed by the humans. These species are threatened mainly due to habitat loss caused by human settlements and by the spreading of agriculture which in turn is destroying their rainforest homeland. Moreover, human hunting for their bushmeat and its commercial market value causes more serious threat for the species. However, international trade of bushmeat has been banned legally and measures to conserve their habitat are implemented in West Africa at various levels. Despite these facts, recent studies as well as analysis from the previous decades have found that conservation outlook for Mandrills and other primates have drastically worsened, necessitating constructive steps by the government officials and other key protection bodies. References: Beaulieu, M., Mboumba, S., Willaume, E, Kappeler, P. M. & Charpentier, M. J. E. (2014). “The oxidative cost of unstable social dominance.” The Journal of Experimental Biology, 217 (15), 2629-2632. Gron, K. J. (2009, October 14). Primate factsheet: Drill (Mandrillus) taxonomy, morphology & ecology. Retrieved from http://pin.primate.wisc.edu/factsheets/entry/drill/taxon. Ingmarsson, L. (1999, June 7). Mandrillus sphinx. Retrieved from http://animaldiversity.org/accounts/Mandrillus_sphinx/ Kingdon, J., Happold, D., Butynski, T., Hoffmann, M., Happold, M & Kalina, J. (2013). Mammals of Africa, Volumes 1-6. A&C Black. “Mandrill.” (n. d). In Denver Zoo. Retrieved from http://www.denverzoo.org/downloads/dzoo_mandrill.pdf “Mandrill.” (2007, June 17). In The Primata. Retrieved from http://www.theprimata.com/mandrillus_sphinx.html Schwartz, J. (2006, November 8). Mandrillus sphinx - Sexual dimorphism and physical diversity of individuals in relation to social status. Retrieved from http://www.scribd.com/doc/103715/Mandrillus-Sphinx-Sexual-Dimorphism-and-Physical-Diversity-of-Individuals-in-Relation-to-Social-Status#scribd “The Masked Mandrill.” (2013). Christian Bush. 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