Orangutan genetics races and reproduction. Review of the orang utan. Its biology and conservation edited by Leobert E. M. de Boer. The Hague Dr. W. Junk Publishers 1982 353 pp. $76код для вставкиСкачать
American Journal of Primatology 9:151-155 (1985) BOOK REVIEW Orangutan Genetics, Races, and Reproduction Review of The Orang Utan. Its Biology and Conservation, edited by Leobert E.M. de Boer. The Hague, Dr. W. Junk Publishers, 1982,353 pp. $76.00 Although the volume The Orang Utan Its Biology and Conservation makes a formidable contribution to the study of the “person of the forest” (Malay translation for the word “orangutan”), almost one third of the contributed articles deal with orangutan cytogenetics. This, however, is not its weakness nor necessarily surprising as the book’s editor, L.E.M. de Boer, authored or coauthored all six papers on cytogenetic topics as they relate to orangutans. It might, however, disappoint those expecting to find the volume biased toward behavioral studies on wild and rehabilitant orangutans. But be assured, the increasingly sophisticated fields of cytogenetics and molecular biology are providing the serious primatologist with a wealth of information that has bearing on the conservation of endangered species both in the wild and in captive populations. As is made clear in one chapter on genetics and conservation of the orangutan, “Genetic studies are pre-eminently suitable to detect the existence of intraspecific difference.” The chromosomal and cytogenetic methods and results (detailed in chapters 4-7) used in the evaluation of the tremendous amount of polymorphism in the orangutan (the most of any hominoid) have until recently been typically used in comparing the orangutan with other primates (especially humans and the other great apes) to determine evolutionary affinities. But knowing how to distinguish a Sumatran from a Bornean orangutan unambiguously (as cytogenetic and chromosomal tests permit) is a “prerequisite of a good conservation policy for wild populations and to proper management of captive stocks.” Characterizing orangutan population genetics (eg, determining the gene frequency of polymorphic loci or the presence of rare lethal alleles) can aid in conservation and zoo management decisions. The information and techniques described in the various chapters should benefit responsible managers of captive orangutans who want to insure a genetically healthy population of animals (eg, captive populations whose genetic structure is similar to wild populations, free of excessive inbreeding, and characterized as to hereditary diseases). The papers on orangutan cytogenetics are, therefore, relevant not only to individuals who have a theoretical interest in population genetics, but also to the practical and responsible managers of relatively small orangutan populations where problems of genetic variability can exist. The other chapters in the volume, which developed out of the 1979 “Workshop on the Conservation of the Orang Utan,” are equally informative and valuable to readers interested in orangutan conservation and reproductive biology. In the first chapter Van Koenigswald presents a n enjoyable and fascinating review of orangutan zoogeography and evolution. In contrast to characterizing populations of orangutans according to genetic loci, the article reviews a few classic studies used to differentiate 0 1985 Alan R. Liss, Inc. 152 I Shapiro orangutan races. For example, the author recounts the study by Selenka 118981who, in the tradition of contemporary phrenologists, distinguished some eight Bornean races (Simia satyrus ssp.) and two Sumatran races (Simia sumatranus ssp.) of orangutan based upon brain capacities and cheek flanges. The comment on races of male orangutans without “flanges” or cheekpads (p 3) indicates that classic observations from the old naturalist tradition should occasionally be questioned. Such “flangeless” males represent the subadult age group of orangutans (Kingsley, chapter 11)and not another race. More significantly, the author details the evolutionary and zoogeographical history of orangutans from the paleontological (primarily dental) evidence that has slowly accumulated over the last two centuries from many areas of Southeast Asia. In the second chapter M. Jones presents a compilation of material concerning captive orangutan histories since their first appearance in Western Europe in 1776. As Jones mentions in the chapter, over 1,400 orangutans have been exported from Borneo and Sumatra during the last two centuries. A vast amount of information has been summarized from the literature and unpublished archives with the international studbook serving a s a reference. A number of tables provide summary data on the importation of wild orangutans, the breeding success of wild-born and/or captive orangutans, and the longevity of orangutans in captivity. The chapter is thus valuable to individuals interested in origins and present state of captive orangutan populations worldwide. Several chapters are specifically aimed a t the managers of zoological collections that maintain orangutans. D. Jones provides a n objective, clinical “cookbook” on orangutan maintenance, nutrition, reproduction and rearing, and handling techniques that have been successful in keeping captive orangutans alive. There is a detailed section on medical concerns which should be of value to zoo veterinarians and others who are interested in the health and well-being of the orangutan. The intentionally clinical texture of this article contrasts with the chapter by Maple on the management of captive orangutan behavior. The psychological wellbeing of captive orangutans is of equal concern to Maple, and a n understanding of this is revealed from detailed behavioral studies of captive orangutans. The results of these studies are discussed in terms of the orangutan social potential in the play and parenting context. The author advises that infants be kept with their mothers and presents methods successfully used to reintroduce hand-reared infants to their mothers. Finally, a mention is given to the orangutan’s climbing and manipulative proclivities, and Maple suggests how exhibits should be constructed or modified to encourage movement and foraging activity. The degree of orangutan social potential is further explored in a n article by Edwards. Interactive and solitary behaviors and use of space were studied in two captive groups (adult and juvenile) of orangutans. The findings of obvious social behavior, age-related differences in activities, differential allocation of cage space, and discrete relationships in captive orangutans does empirically indicate their social potential in a captive setting. The findings, however, would not be surprising to ethologists that have observed wild and captive orangutans. Although the adult males are predominantly solitary, wild orangutans are better described a s “semisocial” [Galdikas, personal communication] and not asocial. In a captive setting, enhancement of social expression and interactions would be expected. The conclusion that observations of wild orangutan social interaction may not always be obvious due to “limitations presented while doing research” shows a failure to appreciate the degree of ecological constraint faced by the red ape. Also, after many thousands of observation hours, it is obvious to observers that wild orangutan social behavior can be observed. Proximate social interaction just doesn’t occur as frequently among certain age-sex classes of wild orangutans (male-male) as it does with TheOrangUtan I 153 the African apes; however, distal social interactions using the vocal-auditory modalities illustrate how the social potential is most frequently expressed [see Schurmann, Rijksen this volume]. Several articles cover aspects of orangutan reproduction. The chapter by van der Werf‘f ten Bosch details reproductive physiology and behavior during the life cycle of the orangutan. Much of it is from zoo literature although the author does not neglect to cite observations made by behaviorists in the field. Many of the behavioral observations concerning various phases of the orangutan reproductive cycle are based on a limited number of citings and, therefore, may not reflect what is “normal.” For example, the author writes (p 202) that following the birth of her infant, the rehabilitant orangutan, Joan, ate the afterbirth. Some rehabilitants do not eat the afterbirth [Galdikas, personal communication]. It is, therefore, difficult to characterize some aspects of the reproductive behavior of orangutans when so few observations have been made. An unusual but interesting account of caged male assistance during the birthing process is given. Again, this is not typical orangutan behavior as a male would probably never witness the birth of his offspring in the wild. The sections on rearing, somatic growth, and mating behavior round out this chapter. The chapter by Kingsley examines the relationship between hormonal production, breeding success, and secondary sexual characteristics in captive male orangutans. Over a period of almost a year and a half, growth rates of secondary sexual characteristics and hormone levels in various age groups of 20 males (juveniles and adolescents, nonflanged adults, adults with growing flanges, and flanged adults) were measured and statistically compared. A number of interesting conclusions were suggested by the data. For example, in exploring whether the presence of a flanged male suppressed the development of flanges in a nonflanged male, Kingsley reports that the onset of flange development preceded separation from the older male and then concludes that the relationship appears to inhibit flange growth in the adult male. Supplemental data are used to bolster the case. Although the hormonal data did not reveal a relationship between the hormones examined and breeding success by males, the paper does illustrate that sensitive laboratory techniques can be used to better understand the dynamics of sexual development and fertility in a n endangered species. Although the next chapter focuses on orangutans, Nadler examines three related aspects of reproductive biology in great apes: cyclicity, periovulatory restriction, and hormonal regulation of sexual behavior. Data are presented that modify Yerkes’ early assertions that 1)female mating initiative and degree of periovulatory restriction of mating is controlled by hormones, while 2) performance of mating outside the periovulatory period reflects a degree of behavioral emancipation from hormonal control. After studying the chimpanzee, Yerkes believed this emancipation was the result of the ape’s advanced taxonomic status and higher intellect. In his comparative study, Nadler shows that male mating initiative, not taxonomic status, regulates mating in captive great apes. With captive adult orangutans, male initiative is very strong, but Nadler points out it isn’t clear how these laboratory results relate to “species-typical” behavior since in the wild, “rape” has been observed to be a subadult male pattern, not a n adult male pattern. Several possibilities are explored but it appears that captive adult orangutans display a different distribution of mating during the female’s cycle because of the male’s strong initiative, male dominance, and the inability of the female to avoid the male’s advances. By providing the female with the ability to avoid the male, Nadler shows that female initiative in captive orangutans can be expressed and is greatest during midcycle. During this time, the adult male is essentially passive, and this pattern more closely reflects what has been observed in the wild. 154 I Shapiro Schurmann’s chapter on mating behavior in wild orangutans confirms the role of female mating initiative in Sumatran orangutans as far as adolescent females are concerned. Galdikas [ 19811 earlier reported similar findings. Although admitting that “rapes” do occur, Schurmann contends that the majority of the sexual interactions leading to copulation occur cooperatively and in consort relationships. In a case history of two individuals, data are presented that show obvious cyclicity in consorting and mating behavior. Since female orangutans show no visible sign of estrus, female proceptivity during midcycle and her clear preference for adult males may be necessary for her to choose a mate and may thus account for the marked sexual dimorphism in this species. In the final three chapters of this volume, the authors examine the orangutan in the context of conservation. Galdikas explores the role of the orangutan as a major seed dispersal agent in the complex tropical rain forest ecosystem. The frugivorous orangutan is seen as a n important modifier of the tropical rain forest both by its physical manipulation of trees and tree parts and, in the context of this article, by processing and dispersing numerous species of seeds. Seed dispersal by orangutans in Tanjung Puting, Central Indonesian Borneo, has been observed a t least in four forms: 1)seed consumption and dispersion via feces, 2) fruit and seed chewing and spitting, 3) carrying fruits a distance before consuming andlor spitting out the seeds, and 4) dropping defective and/or unripe fruits. This last form of orangutan seed dispersal is indirect as the gathering and dropping action provides a number of terrestrial mammals more immediate access to the fruit. Observation and fecal analysis indicate that orangutans can disperse seeds from the majority of the fruits they consume. Galdikas shows that many of those seeds are of plants that have considerable value to humans a s well as to orangutans. The value of the orangutan is thereby increased: it is not only our endangered simian cousin, but a n important seed disperser in a potentially valuable genetic reservoir, that is, the forest it inhabits. The last two chapters deal with more traditional considerations of conservation. The chapter by Aveling is a n account of the state of orangutan conservation efforts in Sumatra, specifically in the areas of law enforcement, habitat protection, and conservation education. The prognosis for orangutan survival is uncertain owing to the threat of huntingltrading and habitat destruction. A number of other uncertainties are also considered: estimates of orangutan populations, ability in enforcing conservation policy and law, and the role of orangutan rehabilitation centers. Aveling gives a review of the efforts that have been made by Indonesian and foreign conservation agencies. Although the author believes there are enough orangutan rehabilitation stations throughout Sumatra and Borneo, the stations can have a n effective role in orangutan conservation, primarily through conservation education. Accomplishments in the area of conservation education and orangutan rehabilitation a t the Ketambe and Bohorok rehabilitation stations are detailed. In the final chapter, Rijksen attempts to clarify some of the confusion and “mystery” surrounding the orangutan: its name, distribution, population density and size, social organization, reproductive strategy, and prospects for survival. For example, after tracing the name for the genera, Pongo, back to the Congolese name for the gorilla, “mpungu,” Rijksen suggests that the old name, Simia satyrus (Linneaus 1766), be restored as appropriate nomenclature for the orangutan. A discussion on various estimates of orangutan population is presented in context with conservation concerns. The description of orangutan social organization and reproductive strategy is necessarily brief but accurate for the most part. Occasionally the author’s interpretations become overly colorful, as in the statement. “For a female in heat the long call of her particular male($ serves as a beacon of love” (p 323). The Orang Utan / 155 Although some of the information in this chapter has been covered earlier in the volume, Rijksen uses the information to consider measures he feels will ensure the ape’s survival. For example, a suggestion is presented concerning the calculation of the minimal size of a protected area necessary to insure the survival of orangutan populations. Regarding orangutan rehabilitation centers, the author, like Aveling, views them as a valuable component of law enforcement and conservation efforts; however, Rijksen considers tourism in the context of orangutan rehabilitation inadvisable due to the potential of disease transfer and rehabilitation setbacks. The suggestion is made that rehabilitant orangutans be transferred to protected areas of Borneo and Sumatra where orangutans are not presently found so as not to contaminate existing wild populations. Although the book provides a n excellent array of topics concerning orangutan biology and conservation, it does not cover every aspect of this growing field. For example, i t does not contain any articles that express the excitement that has been generated in recent years in primate developmental biology, psychobiology, and sociobiology. A volume like this, however, must limit itself, and in that respect it succeeds by concentrating on several important disciplines which illustrate the attempts that have been made over the past decade to facilitate the survival of the orangutan in both captivity and in the wild. Finally, the editor could have organized the articles more carefully by placing them into appropriate sections such as cytogenetics, reproductive biology, and conservation, etc. This, however, is a minor point for the reader will find the volume to be a n informative and useful reference. Gary L. Shapiro Department of Zoology University of Oklahoma Norman, OK REFERENCES Galdikas, B.M.F. Orangutan reproduction in the wild, pp. 281-300 in THE REPRODUCTIVE BIOLOGY OF THE GREAT APES. C.E. Graham, ed. New York, Academic Press, 1981. Selenka, E. Menschenaffen: Rassen. SCHADEL UND BEZAHNUNG DES ORANG-UTAN. Wiesbaden, Kreidel, 1898.