Factors influencing the diversity
The high diversity of anthropoid Primates in the terra firma between the Yavarí and Amazon probably arose from a combination of factors including Pleistocene refugia, river dynamics and diversity of flora. Several authors have suggested that the forests between the Yavarí and Amazon may have been part of a Pleistocene refuge (Haffer, 1969; Prance, 1985). However, Haffer (1969) limits this refuge to the mouth of the Yavarí and Prance (1985) includes this area as a continuous refuge with much of the northern Peruvian and Ecuadorian Amazon. Unfortunately, plotting of Pleistocene refugia has often been skewed towards areas which have received the greatest attention by field collectors (Nelson et al., 1990). The Yavarí is an area that has received little or no attention in field collections and this may account for its unclear position in the hypotheses of Pleistocene refugia.
The high diversity of allopatric Primates in Amazonia may result from effective river boundaries (Ayres and Clutton-Brock, 1992). Indeed, boundaries imposed by the Yavarí and Amazon rivers might have contributed to the high diversity of Primates in the Reserva Comunal Tamshiyacu-Tahuayo. The Amazon river is the most effective river boundary in the entire basin and limits the geographical ranges of 39 Primate species (Ayres and Clutton-Brock, 1992). In contrast, the Yavarí is considerably smaller and is less effective as a barrier. The Amazon changes its flow from north to east before reaching the mouth of the Yavarí. Thus, geographical distributions of several Primate species that occur west of the Yavarí river are limited on their western and northern range by the Amazon. This area coincides with the Reserva Comunal Tamshiyacu-Tahuayo.
Another factor which has probably influenced the diversity of Primates in the Reserva Comunal Tamshiyacu-Tahuayo is the floral diversity of western Amazonia. The diversity of trees in the basin of western Amazon is considerably greater than in the eastern Brazilian and Guiana shields (Gentry, 1988). Likewise, Primate diversity of western Amazonia is greater than the eastern basin. Ayres (1986) has suggested a positive relationship between the floral and Primate diversities when comparing eastern and western Amazonia. Undoubtedly, the Primate richness of the Reserva Comunal Tamshiyacu-Tahuayo has been influenced by the high floral diversity of the forests between the Yavarí and Amazon. However, it is likely that no single factor has contributed to the observed Primate diversity of the Reserva Comunal Tamshiyacu-Tahuayo, but rather a combination of the factors and historical events mentioned above.
Conserving the diversity
As the focus on biological,diversity accentuates, the importance of species endemism is often used to determine where Conservation efforts should be focussed (Western and Pearl, 1989). However, it is equally important to consider the endemic nature of species assemblages. Indeed, exceptionally diverse areas are themselves an endemic occurrence, but on an ecosystem level (Solbrig, 1991).
The need to properly manage the forests of the Reserva Comunal Tamshiyacu-Tahuayo is paramount for its Conservation. One of the more urgent actions requires a cessation on the hunting of Primates, because current exploitation is decreasing Primate densities and threatening the assemblage.
The hunting pressure in Tahuayo-Blanco appears to be a result of its proximity to the city of Iquitos which can be reached by boat in approximately 10 h. Consequently, hunters of Tahuayo-Blanco are influenced primarily by the value of game meat in the local markets of Iquitos (Bodmer et al., 1990a). While Primates are only infrequently used as commercialized game meat, they play an important part in the economics of game meat hunters. Game hunters seek ungulates and large-bodied rodents for their greater market accessibility and sell virtually all of these larger animals for cash. Primates and other small-bodied mammals are taken for food during hunting forays and substitute for economic losses that hunters would incur if they consumed the commercially valuable meat of large-bodied mammals. Thus, Primates are experiencing substantial harvesting pressure, because of the socioeconomic system of local meat hunters.
A management plan for game hunting in the Reserva Comunal Tamshiyacu-Tahuayo has been developed for the Tahuayo-Blanco region. The management model considers population biology of harvested species, economic cost-benefit analysis of the hunters, and social limitations of game management in this region (Bodmer et al., 1992).
The model for Tahuayo-Blanco requires that market benefits from game meat be derived only from male artiodactyls and large-bodied rodents and subsistence consumption from female artiodactyls and large-bodied rodents. Indeed, meat from female artiodactyls and large-bodied rodents used for subsistence consumption will substitute meat lost from Primates and other small-bodied mammals. The plan is that hunters will no longer have a stimulus to harvest Primates for consumption when meat from female artiodactyls and large-bodied rodents is available.
