PIPIAPAN@VMS.MACC.WISC.EDU ("Dennis R. Rasmussen") (10/11/90)
October 10, 1990 There has been some discussion in the population-biology newsgroup regarding E.O. Wilson's lecture to the Swedish Academy of Science. I've been drawn into this as a result of a personal response to Xia. Let me reiterate the discussion thus far and then append further discussion: ------------------------------------------------------------------------------ the start of the discussion: ------------------------------------------------------------------------------ From: IN%"xia@cc.helsinki.FI" 5-OCT-1990 13:13:05.48 To: population-biology@cc.helsinki.FI Subject: E.O. Wilson on social organization and speciation. Dear Colleagues, In a recent lecture in Swedish Academy of Science, Dr. E.O. Wilson of Harvard proposed the following thesis: 1. Speciation in social primates is rapid, with rich species diversity. 2. It has been hypothesized that the rapid speciation in social primates is due to relative isolation of breeding among different social groups, i.e., random drift leads to diversification and eventually speciation. 3. If this hypothesis is true, then why there is no such rapid speciation and rich diversity in social insects, especially, social ants? 4. Answer: A colony of social ants is not equivalent to a social group in primates. The former is a single superorganism. The relative social isolation among ant colonies does not lead to non-random mating when queens are getting inseminated. I have seen no data on inbreeding in social primates, neither have I seen evidence for random mating in social ants. Besides, there are inbreeding species with little speciation and random-mating species with rapid speciation (Forget this last sentence because an inbreeding species today may be random- mating in the remote past.). Any comments on this? Perhaps Allan Rogers has something to say about primates? BTW, Dave of Genbank mentioned Joel Felsenstein. I hope that anyone who is currently associated with Joel or whoever famous could managed to get a few more familiar names into this newsgroup. Xuhua ------------------------------------------------------------------------------ my personal note to xia: ------------------------------------------------------------------------------ From: WIRCS1::PIPIAPAN "Dennis R. Rasmussen" 6-OCT-1990 08:37:01.90 To: IN%"xia@cc.helsinki.FI",pipiapan Subject: E.O.Wilson Dear Xuhua: Perhaps the following may be of some help. In a recent lecture in Swedish Academy of Science, Dr. E.O. Wilson of Harvard proposed the following thesis: 1. Speciation in social primates is rapid, with rich species diversity. 2. It has been hypothesized that the rapid speciation in social primates is due to relative isolation of breeding among different social groups, i.e., random drift leads to diversification and eventually speciation. > These are relative statements. There is, however, considerable gene flow between social groups of primates, more than thought in the 60's literature. The early literature was based, in part, on provisioned and isolated groups of nonhuman primates. In addition many of the groups of nonhuman primates that are studied are "island" populations surrounded by encroaching human populations; as a result there is relatively little gene flow. At one time, for example, a baboon troop was considered so isolated as to be equivalent to a deme. I studied baboons in Tanzania, East Africa at a location where 100s of troops existed (Mikumi National Park which is contiguous with the Selous Game Reserve). There it was quite apparent that exceptionally high rates of transfers existed between troops. See: Rasmussen, D. R. (1979). Correlates of patterns of range use of a troop of yellow baboons (Papio cynocephalus). I. Sleeping sites, impregnable females, births, and male emigrations and immigrations. Animal Behaviour, 27, 1O98- 1112. Rasmussen, D. R. (1981). Communities of baboon troops (Papio cynocephalus) in Mikumi National Park, Tanzania: A preliminary report. (Folia Primatologica), 36, 232-242. Rasmussen, D. R. (1983). Correlates of patterns of range use of a troop of yellow baboons (Papio cynocephalus). II. Spatial structure, cover density, food gathering, and individual behavior patterns. Animal Behaviour, 31, 834- 856. Warm regards, Dennis Rasmussen Animal Behavior Research Institute 314 S. Randall Madison, Wisconsin 53715 ------------------------------------------------------------------------------ From: IN%"rogers@anthro.utah.edu" "Alan R. Rogers" 6-OCT-1990 08:50:14.43 To: pop-bio@largo.ig.com Subject: E.O. Wilson on social organization >2. It has been hypothesized that the rapid speciation in social >primates is due to relative isolation of breeding among different >social groups, i.e., random drift leads to diversification and >eventually speciation. > >3. If this hypothesis is true, then why there is no such rapid >speciation and rich diversity in social insects, especially, >social ants? > >4. Answer: A colony of social ants is not equivalent to a social >group in primates. The former is a single superorganism. The >relative social isolation among ant colonies does not lead to >non-random mating when queens are getting inseminated. That answer makes sense to me, but I'll bet Sewall Wright would have added that speciation usually involves a shift from one adaptive peak to another, and that this requires that the partially isolated breeding groups be fairly small. Primate populations are not nearly as dense as those of social insects, and their local groups are much smaller. In addition, they can't fly. Bodies of water and (for arboreal primates) areas devoid of trees are probably more effective barriers to primates than to bees and wasps. This should also increase the isolation of local primate populations, and thus facilitate speciation. Alan Rogers INTERNET: rogers@arsun.utah.edu USMAIL : Dept. of Anthropology, Univ. of Utah, S.L.C., UT 84112 PHONE : (801) 581-5529 ------------------------------------------------------------------------------ Xuhua's comment to Alan Rogers: ------------------------------------------------------------------------------ From: IN%"xia@cc.helsinki.FI" 8-OCT-1990 22:23:58.43 To: population-biology@cc.helsinki.FI Subject: Social organization and speciation (For Alan Rogers) Dear Alan, I do not share your belief that inter-group isolation played a role in primate speciation, for the following reason. The reason was not mine, but suggested to me by Dennis Rasmusen (Sorry for quoting your name without asking for your permission, Dennis). Dennis pointed out that inter-group isolation we observed today does not mean that such isolation existed many years ago, and it is the isolation many years ago that could explain the species diversity we observed today in social primates. The inter-group isolation among social primates may well be a recent phenomenon due to fragmentation of their habitats caused by human activities. Xuhua ------------------------------------------------------------------------------ Amplification of my personal note, response to Alan Rogers and further comments: ------------------------------------------------------------------------------ First let me note that I am an animal behaviorist and my areas of expertise are in primate social behavior and primate social ecology. 1. Primate groups, demography and troop transfer: There is a growing literature indicating that demography exerts a profound influence on social organization and transfer between groups. For example, the Altmann's and their colleagues have been studying baboons at Amboseli in Kenya where the population has diminished. This decrease in group size and higher mortality seem likely to have generally decreased rate of transfers between groups. The troop I studied in Mikumi National Park was in a local population that appeared to be expanding and this may be a major factor in the much higher rate of exchange of members between troops. The troops studied at Gombe National Park by Packer and others appeared to be in a more stable local population with intermediate rates of transfer between groups. 2. Troop transfer as a barrier to gene flow: Although demography may therefore have a strong influence on the rate of movement between troops, no matter if the population is decreasing, stable or expanding, movement between troops appears to nearly always be associated with potential agonistic behavior, wounding and sometimes death. As a result the xenophobic responses of group members does impede gene flow. 3. Past and present environments: Like Darwin, we tend to believe that the forces of natural selection we see and record today are similar to those that occurred in the past. However we must take into account the profound influence human population growth has had on the population structure of most nonhuman primates. For example, many groups are isolated and have become island populations cut off from other groups by the "sea" of humanity. The influences of human populations on primate social groups and natural selection goes far beyond decreasing population size and isolating groups. For example, the large mammalian predators that seem likely to have been a major influence on the social organization and behavior of ancestral populations of nonhuman primates have been among the first to be killed and diminished by humans. As a result most primate groups studied have reduced or no large mammalian predators (there were many mammalian predators at Mikumi where I studied baboons such as lions, leopards, hyenas and wild dogs but even there the population of these predators seem likely to be less than 100 years ago). This fact may account for the increased emphasis on sexual selection as a factor influencing sexual dimorphism in primates over the earlier emphasis on predators. Again, we must not be deceived by present selection pressures: if we observe primates in a habitat with say, no lions, we would of course be wrong to conclude that lions have not been a selective pressure on the ancestors of the primates we observe. 4. E. O. Wilson's comments seem correct: One can give only so much detail in a lecture. His comparisons are made across the animal kingdom and nonhuman primate groups do represent a differentially permeable barrier to gene flow. 5. Xuhua's comment is based on an qualitative rather than a quantitative approach. I share his apparent doubts that single primate groups in ancestral environments would have formed closed demes in which major steps towards speciation occurred (although some provisioned colonies may now be nearly closed demes). I rather doubt if this is what Professor Wilson had in mind. However transfers between groups are met with xenophobic responses of group members and this does retard gene flow. Group structure is therefore a quantitative factor influencing genetic differentiation of nonhuman primate groups. 6. Roger's comment also seems correct and he is correct in pointing out that many other factors, such as bodies of water, are barriers to gene flow in nonhuman primates. 7. Using common baboons as an example, it appears as if gene flow between groups has been sufficient for species to exist over huge areas of very different environments, partially separated by bodies of water, by differences in demography and etc. For example the Altmanns and I studied the same species of baboon (Papio cynocephalis) in very different environments and separated by bodies of water, thousands of groups, hundreds of miles, and diverse demographic structures. This does not mean that there are not marked phenotypic, and most likely genotypic, differences between local populations. If one drives along an East African road and watches baboon groups pelage differences and physical characteristics such as chest depth and tail curves are readily apparent. ------------------------------------------------------------------------------ The above provides only a glimpse at the complexity present. There is much theoretical, computer simulation, and field work that must be done by generations of scientists. The following references provide a start into this complex nexus of social organization, demography, ecology, and population biology. Altmann, S. A., & Altmann, J. (1970). Baboon ecology: african field research. University of Chicago, Chicago. Anderson, C. M. (1986). Predation and primate evolution. Primates, 27, 15- 39. Anderson, C. M. (1981). Subtrooping in a Chacma baboon (Papio ursinus) population. Primates, 22, 445-458. Bernstein, I.S., Gordon, T. P., & Rose, R. M. (1974). Factors influencing the expression of aggression during introductions to rhesus monkey groups. In: Holloway, R. L. (ed.), Primate aggression, territoriality and xenophobia: a comparative perspective. Academic Press, New York. pp. 211- 240. Collins, D. A. (1984). Spatial pattern in a troop of yellow baboons (Papio cynocephalus) in Tanzania. Animal Behaviour, 32, 536-553. Dittus, W. P. J. (1975). Population dynamics of the toque monkey Macaca sinica. In: Tuttle, R. H. (ed.), Socioecology and Psychology of Primates. Aldine, Chicago. pp. 125-151. Hausfater, G. (1974). Dominance and reproduction in baboons (Papio cynocephalus): a quantitative analysis. Contributions to Primatology, 7, 1- 150. Leopold, A. (1949). A sand county almanac. Oxford University Press, New York. Packer, C. (1979a). Inter-troop transfer and inbreeding avoidance in Papio anubis. Animal Behaviour, 27, 1-36. Rasmussen, D. R. (1981). Communities of baboon troops (Papio cynocephalus) in Mikumi National Park, Tanzania: A preliminary report. Folia Primatologica, 36, 232-242. Rasmussen, D. R. (1988). Studies of food enhanced primate groups: current and potential areas of contribution to primate social ecology. In: Fa, J. E., & Southwick, C. H. (eds.), Ecology and behaviour of food-enhanced primate groups. Alan R. Liss, New York, pp. 313-346. Struhsaker, T.T. (1973). A recensus of vervet monkeys in the Masai-Amboseli game reserve, Kenya. Ecology, 54, 930-932. Struhsaker, T.T. (1976). A further decline in numbers of Amboseli vervet monkeys. Biotropica, 8, 211-214. Sugiuama, Y. (1976). Life history of male Japanese monkeys. In: Advances in the Study of Behaviour. J. S. Rosenblatt, R. A. Hinde, E. Shaw, & C. Beer (eds.), Vol. 7, pp. 255-283. Sugiyama, Y. & Ohsawa, H. (1982). Population dynamics of Japanese macaques at Ryozenyama: III. Female desertion of the troop. Primates, 23, 31-44. Washburn, S. L., & DeVore, I. (1961). Social behavior of baboons and early man. Viking Fund Publications in Anthropology, 31, 91-104. Wilson, E. O. (1971). Competitive and aggressive behavior. In: Man and beast: comparative social behavior. (J. F. Eisenberg & W. S. Dillon eds.). pp. 181-217. Smithsonian Institution Press, City of Washington. ------------------------------------------------------------------------------