Dopamine Gates Visual Signals in Monkey Prefrontal Cortex Neurons

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Genetic and evolutionary relationships among Asian Macaques

Published gene frequency data, checked for consistency of allele definitions across laboratories and for comparability of geographically identical samples, were pooled into a data set containing frequencies at nine loci for each of 20 populations that encompassed 10 macaque species. Genetic distances were calculated by the methods of Kidd and Cavalli-Sforza (1974). These distances were used to construct phylogenetic trees and to evaluate the relationships between divergence times and effective population sizes. Inter-and intraspecific genetic distances and the groupings defined by phenetic tree analyses support Fooden’s (1976) classification of the genus Macacainto four species groups. A paleozoogeographical model of Asia including the known times of major sea-level changes allows us to explain Macacainto four species groups. A paleozoogeographical model of Asia including the known times of major sea-level changes allows us to explain qualitatively the inferred evolutionary relationships among macaque species. Many assumptions are required in order to estimate the variables necessary in the quantitative prediction of genetic differences for a comparison between any two populations. Examination of those assumptions demonstrates the need for more accurate genetic as well as paleozoogeographic information. An erratum to this article is available at .     

Testis size,epididymis weight,and sperm competition in rhesus macaques

The intensity of sperm competition is often measured using the gonadosomatic index (testes/body weight). But sperm competition could be mediated more by size of the epididymis than by size of the testicles, and little information is available on the relationship between testicular and epididymal size. We found that both organs were positively correlated in size among male rhesus macaques. Body weight accounted for over 70% of the variance in testicle size and volumetric estimates of testicle size accurately reflected testicle weight. We conclude that methods for ascertaining testicle size are accurate, but the covariation in size between testicles and epididymis will hamper understanding of the physiological mechanisms involved in sperm competition in primates. © 1993 Wiley-Liss, Inc.     

A ten-month study of endogenous testosterone levels and behaviour in outdoor-living female rhesus monkeys (Macaca mulatta)

Endogenous testosterone levels were measured in association with sexual, aggressive, and social/affiliative behaviors in 11 outdoor-housed female rhesus monkeys over a ten-month period. Several behaviors (sex directed toward the male, sex received from the male, aggression directed toward the male, submission directed toward the male, submission directed toward the female, and groom another female) were significantly (p<0.05) positively correlated with testosterone in from one to five females. No trends were strong enough across all females to suggest that any of these correlations have species-wide significance. Factor analysis revealed clearcut clusters of behaviors, but elevations in testosterone were not strongly associated with any of these clusters. It is concluded that endogenous testosterone levels have little measurable effect on overt behavior in female rhesus monkeys.     

Weed macaques: The evolutionary implications of macaque feeding ecology

Patterns of feeding ecology among the living macaques conform poorly with recognized phyletic distinctions within the genus because there is an important ecological division which cross-cuts phyletic groupings. This division, between weed species and non-weed species, is based on the differing abilities of macaques to tolerate and even prosper in close association with human settlements. Based on available information about their ecology in the wild, we tentatively assign macaque species to these two categories. Finally, we consider the implications of our argument for scenarios of the initial spread of the macaques.     

Establishment of primate lymphoblastic cell lines by coculture with a simian T-cell leukemia virus-1 positive, hypoxanthine-guanine-phosphoribosyltransferase negative Japanese macaque cell line

A cell line (JAMH17+) resistant to 8-azaguanine was established from a human T-cell leukemia virus type 1 related virus (simian T-cell leukemia virus-1) positive Japanese macaque cell line. Lymphoblastic cell lines were established from the peripheral blood mononuclear cells of humans, hominoids, and several species of macaques by coculture with JAMH17+ in hypoxanthine-aminopterin-thymidine medium. HTLV-1 specific antigen was detected in some of the established cell lines. Phenotypic analysis showed that several cell lines of crab-eating macaques expressed Leu11a antigen, which is a marker of human natural killer cells.     

The genetic structure of a primate species: Rhesus macaques and other Cercopithecine monkeys

Among rhesus macaques (Macaca mulatta)and other cercopithecine monkeys, social groups occupying adjacent home ranges (i.e., members of the same local population) exchange individuals and genes and thus exhibit marked genetic similarities. To assess the degree to which this pattern extends beyond the local population, the genetic structure of M. mulattaand six other primate species was determined using Nei’s (1973) gene-diversity analysis. The genetic similarities seen among social groups in the Dunga Gali population of M. mulatta (Melnick et al.,1984a) can be seen over the entire species range. Comparison of these results with the structures of other similarly organized primate species indicates that (1) the average social group contains most of its local population’s genetic diversity, (2) the average local population contains the majority of the genetic diversity found in the region to which it belongs, and (3) the proportion of species gene diversity found in the average regional population varies substantially between species. Genetic homogeneity within local and regional populations is probably the product of gene flow. The application of a number of analytical models of selection and gene flow strongly suggests that gene flow, genetic drift, and zoogeography offer a more parsimonious and plausible explanation for interspecific variation in regional differentiation than does stabilizing selection.     

Novel hemoglobin components and their amino acid sequences from the crab-eating macaque (Macaca fascicularis)

Summary We found two types of hemoglobin, T and R, from the crab-eating macaque and compared those to A and Q previously reported. The 22 animals studied showed six different phenotypes, A, R, QA, QT, QAT, and QAR. Analysis of the complete amino acid sequences for the chains of hemoglobins Q, A, T, and R revealed that amino acids at four positions, 8, 55, 71, and 78 from the N-terminal, are variable. In the ^A chain, Thr, Val, Gly, and Gln occupy these positions, and in the ^Q chain the analogous amino acids are Thr, Val, Asp, and Gln, respectively. In the newly found ^T chain they are Thr, Val, Gly, and His; and in the ^R chain, they are Ser, Ile, Gly, and His, respectively. Two amino acids (8 Thr and 79 Gln) in ^A of the crab-eating macaque were found to be different from those in the chain of the Japanese macaque.     

Development of tool use in a macaque and a gorilla

The development of the capacity to use a stick as a tool was tested in a macaque (Macaca fuscata) and a gorilla (Gorilla gorilla gorilla) infants that had previously shown to be able to use strings and supports as dragging tools. Subjects were tested between 15 and 38 months of age. Different levels of competence between the subjects emerged over testing. The macaque developed a stereotyped strategy to cope with the problem, only getting random successes, whilst the gorilla developed a flexible strategy and revealed to be able to mentally represent the solution of the problem. In fact, when not successful using the stick, the gorilla thought out an alternative strategy, choosing and adapting a new object to use it as a tool.