Reproductive parameters of female Japanese macaques: Thirty years data from the arashiyama troops,Japan

Over a 30-year period from 1954 to 1983, 975 live births were recorded for Japanese macaque females at the Iwatayama Monkey Park, Arashiyama, Japan. Excluding unknown birth dates, primiparous mothers gave birth to 185 infants (182 cases with age of mother known) and multiparous mothers gave birth to 723 infants (603 cases with age of mother known). The peak month of birth was May with 52.3% of the total births occurring during the period. Multiparous females who had not given birth the previous year did so earlier than multiparous females who had given birth the previous year and also earlier than primiparous females. Among the females who had given birth the previous year, females whose infant had died gave birth earlier than females who had reared an infant the previous year. The offspring sex ratio (1:0.97) was not significantly different from 1:1, and revealed no consistent association with mother's age. Age-fecundity exhibited a humped curve. The annual birth rate was low at the age of 4 years but increased thereafter, ranging between 46.7% and 69.0%, at between 5 and 19 years of age, but again decreased for females between 20 and 25 years of age. Some old females displayed clear reproductive senescence. The infant mortality within the first year of age was quite low (10.3%) and the neonatal (less than 1 month old) mortality rate accounted for 49.0% of all infant deaths. There was no significant difference between the mortality rates of male and female infants. A female's rank-class had no apparent effect on the annual birth rate, infant mortality, and offspring sex ratio. These long-term data are compared with those from other primate populations.     

Population and social dynamics changes in ring-tailed lemur troops at Berenty,Madagascar between 1989 - 1999

In the present study, we recorded all births, immigrations, deaths, and emigrations for a population of ring-tailed lemurs at Berenty Reserve, Madagascar, between September 1989 and August 1999. In September 1989, three troops (C, B, and T) inhabited the study area of 14.2 ha. During the 10-year period, eight troop divisions, six evictions of females, and three troop takeovers of ranges by other troops occurred in and around the study area. Consequently, in August 1999, the number of troops in the same area increased to six (CX, C1, C2A, C2B, T1, and T2). The number of lemurs aged >1 year increased from 63 to 82, which resulted from 204 births, 58 immigrations, 125 deaths, and 118 emigrations. Of the 204 newborn lemurs during the study period, 103 died, 44 emigrated outside the study area, and 57 remained within the study area. The total number of lemurs that emigrated from natal troops was 69 (54 males and 15 females). Natal males left their troops around the age of 3. Non-natal males changed troops after a tenure varying from 1 to 7 years. Survival curves showed a fall in survival rates of both sexes to < 0.5 between the ages of 2 and 3. For females, the survival rate gradually decreased to < 0.2 at the age of 9. On the other hand, due to emigration, the survival rate of males could not be determined after the age of 5 yr. Since some males attained high-rank at the age of 6 – 10 yr, the prime age for male ring-tailed lemurs is thought to be around 7 – 10 yr. Ring-tailed lemurs are essentially female philopatric, because all cases of females leaving natal troops resulted from troop divisions or forced evictions. Such social changes may have resulted from competition among females. All cases of troop divisions or evictions occurred in larger troops consisting of ≥20 lemurs, and only a few females could rejoin their troops. When males joined such a female-group, a new troop was formed. Although promoted by an increase in population, frequent emigrations of females from original troops are the characteristics of ring-tailed lemurs at Berenty.     

Daytime deliveries observed for the ring-tailed lemurs of the berenty reserve, Madagascar

In the Berenty Reserve, Southern Madagascar, of the 16 deliveries recorded for ring-tailed lemurs from 1995 and 1997, 10 cases occurred during daytime hours (07:00 – 16:59). Four mothers lost contact with their troop members during parturition, but were able to rejoin them after about one hour. No attack from the individuals of the neighboring groups or predators on the mothers or their newborn infants was observed, whereas, other females of the mother’s own troop attacked them after delivery in two cases. Such daytime delivery may have originated from the circadian rhythm of the species’ nocturnal ancestors, who might have given birth during the daytime. This pattern may now be a non-adaptive feature, in agreement with the “evolutionary disequilibrium hypothesis (EVDH).”     

Effects of spatial proximity and alliances on dominance relations among female ring-tailed lemurs (Lemur catta) at Berenty Reserve, Madagascar

In the present study, we describe a change in the dominance rank of the top-ranking female in a wild troop of ring-tailed lemurs (Lemur catta) at Berenty Reserve, Madagascar. After the top-ranking female fell to the bottom-ranking position, she was able to outrank a low-ranking female with the support of her adult daughter or an unrelated high-ranking female. These results indicate that, as in cercopithecine monkeys such as macaques and baboons, close proximity and alliances influence dominance relations among adult females in a wild troop of ring-tailed lemurs.     

Demographic and life-history patterns in a population of ring-tailed lemurs (Lemur catta) at Beza Mahafaly Reserve,Madagascar: a 15-year perspective

Over 15 field seasons (1987-2001), we collected census and life-history data on a population of individually identified ring-tailed lemurs at the Beza Mahafaly Reserve, Madagascar. No significant difference was found in population size over the study period, though a marked decline in the population occurred following a 2-year drought. The population rebounded rapidly after the immediate postdrought period. There was nearly a complete replacement of individuals over the study period. Average group size is 11.5 animals, and adult male to female sex ratio is 0.92. Most females reproduce annually, and the average fecundity rate is 84.3%. The greatest variability in fecundity is found among old females. We suggest that ring-tailed lemur females follow an "income breeding" strategy, i.e., females use maximum resources during reproduction rather than relying on fat stores, as do "capital breeders." Infant mortality to 1 year of age in a nondrought year is 52%, higher than infant mortality in small to medium-sized anthropoids. The oldest known female was 18 years old in 2001. We suggest that 18-20 years may represent the maximum life-span for wild ring-tailed lemurs. Because males regularly emigrate from the population, we have no data regarding male life-span; however, there is some indication that males do not survive as long as females. Group fission has occurred three times: twice from one parent group living in the driest area of the reserve, with the most dispersed food resources. We suggest that the reproductive strategy that has evolved in this species, wherein females reproduce early in life and annually until old age, is a response to the unusual climate and environmental conditions under which Lemur catta has evolved.     

Influence of group size on reproductive success of female ring-tailed lemurs: distinguishing between IGFC and PFC hypotheses

Based on data obtained over a period of 11 years from female ring-tailed lemurs (Lemur catta), we analyzed the correlation between group size and female reproductive parameters. The birth rate and mean number of surviving infants 1 year after birth per adult female generated an inverted U-shaped curve when plotted against group size (although not significant) and number of adult female members. Infant mortality rate did not have a consistent correlation with group size and number of adult female members. Thus, our findings were similar to the predictions of Wrangham’s inter-group feeding competition hypothesis.     

Reproductive parameters over a 37-year period of free-ranging female Borneo orangutans at Sepilok Orangutan Rehabilitation Centre

We analysed the reproductive parameters of free-ranging female orangutans at Sepilok Orangutan Rehabilitation Centre (SORC) on Borneo Island, Sabah, Malaysia. Fourteen adult females produced 28 offspring in total between 1967 and 2004. The average censored interbirth interval (IBI) (i.e. offspring was still alive when mother produced a next offspring) was 6 years. This was shorter than censored IBIs reported in the wild but similar to IBIs reported for those in captivity. The nonparametric survival analysis (Kaplan-Meier method) revealed a significantly shorter IBI at SORC compared with wild orangutans in Tanjung Putting. The infant (0–3 years) mortality rate at SORC of 57% was much higher than rates reported both in the wild and captivity. The birth sex-ratio was significantly biassed toward females: 24 of the 27 sex-identified infants were females. The average age at first reproduction was 11.6 years, which is younger than the age in the wild and in captivity. The high infant mortality rate might be caused by human rearing and increased transmission of disease due to frequent proximal encounters with conspecifics around the feeding platforms (FPs). This young age of first reproduction could be because of the uncertainty regarding estimated ages of the female orangutans at SORC. It may also be affected by association with other conspecifics around FPs, which increased the number of encounters of the females with males compared with the number of encounters that would take place in the wild. Provision of FPs, which improves the nutritional condition of the females, caused the shorter IBI. The female-biassed birth sex-ratio can be explained by the Trivers and Willard hypothesis. The female-biassed sex ratio could be caused by the mothers being in poor health, parasite prevalence and/or high social stress (but not food scarcity) due to the frequent encounters with conspecifics around FPs.     

Maternal responses to dead and dying infants in wild troops of ring-tailed lemurs at the Berenty Reserve,Madagascar

We describe responses of seven mothers and other troop members to dead and dying infants in several troops of ring-tailed lemurs(Lemur catta) at the Berenty Reserve, Madagascar. In contrast to mothers in simian species, ring-tailed lemur mothers rarely carried their dying, immobile or dead infants. However, they sniffed, licked, and touched them even after they had died. While the dying infants were still peeping, their mothers remained near them, and 15 to 76 min after the infants ceased to peep, they were left by their mothers. Six of the seven mothers returned to their dead infants several times within the first few hours after they had left them. All seven mothers gave repeated calls, such as “mew” and “pyaa,” when they were separated from either their dead infants or other troop members or both. Thus, each mother exhibited some form of maternal behavior toward her dead infant for hours after its death. These results indicate that there may not be a great gap in terms of maternal affection between simian and prosimian mothers. We also discuss visuospatial memory ability in ring-tailed lemurs and the causes of the infants’ deaths.     

A summary of the workshop on passive immunization using monoclonal antibodies for HIV/AIDS, held at the National Institute of Allergy and Infectious Diseases, Bethesda, 10 March 2006

Passive immunization with monoclonal antibodies (MAbs) has been shown to prevent a wide variety of diseases. Currently, there are no MAb products that are licensed for use for immunotherapy or immunoprophylaxis against infection by HIV. However, there are several rational arguments that can be advanced for the use of a passive immunization approaches for counteracting HIV much as for other diseases especially with respect to mother-to-child transmission (MTCT) of HIV and immediate post-exposure situations. Several arguments questioning the feasibility of the approach based on availability of effective drugs, high cost of production and distribution of the MAbs among others, also get raised. It seems that the field now is looking at some promising MAbs as well as several alternate ways to manufacture antibodies and which hopefully may positively affect cost-related issues. This summary of a workshop held to assess the role of MAbs in the treatment and prevention of HIV/AIDS provides a fairly comprehensive analysis of the usefulness of MAb technology for future HIV/AIDS research.     

A combined method for determining inhibition type, kinetic parameters, and inhibition coefficients for aerobic cometabolism of 1,1,1-trichloroethane by a butane-grown mixed culture.

A combined method for determining inhibition type, kinetic parameters, and inhibition coefficients is developed and presented. The method was validated by applying it to data obtained from batch kinetics of the aerobic cometabolism of 1,1,1-trichloroethane (1,1,1-TCA) by a butane-grown mixed culture. The maximum degradation rates (k(max)) and half-saturation coefficients (K(s)) were independently determined in single compound tests, and compared with those obtained from inhibition tests. The inhibition type was determined using direct linear plots at various substrate and inhibitor concentrations. Kinetic parameters (k(max) and K(s)) and inhibition coefficients (K(ic) and K(iu)) were determined by nonlinear least squares regression (NLSR) fits of the inhibition model determined from the direct linear plots. Initial guesses of the kinetic parameters for NLSR were determined from linearized inhibition equations that were derived from the correlations between apparent maximum degradation rates (k(app)(max)) and/or the apparent half-saturation coefficient (K(app)(s)) and the k(max), K(s), and inhibitor concentration (I(L)) for each inhibition equation. Two different inhibition types were indicated from the direct linear plots: competitive inhibition of 1,1,1-TCA on butane degradation, and mixed inhibition of 1,1,1-TCA transformation by butane. Good agreement was achieved between independently measured k(max) and K(s) values and those obtained from both NLSR and the linearized inhibition equations. The initial guesses of all the kinetic parameters determined from linear plots were in the range of the values estimated from NLSR analysis. Overall the results show that use of the direct linear plot method to identify the inhibition type, coupled with initial guesses from linearized plots for NLSR analysis, results in an accurate method for determining inhibition types and coefficients. Detailed studies with pure cultures and purified enzymes are needed to further demonstrate the utility of this method.     

A simulation test of hominoid species number at Lufeng, China: implications for the use of the coefficient of variation in paleotaxonomy

High dental metric variation in the large hominoid sample from the late Miocene site of Lufeng, China has been interpreted in two ways: (1) there are two morphologically similar species that broadly overlap in size, and (2) there is one species that is more highly sexually dimorphic in dental size, and perhaps in body size, than any extant primate. It has been claimed that the high levels of dental metric variation falsify the single-species hypothesis, which has been viewed implicitly as corroboration of the two-species hypothesis. However, the two-species hypothesis has not been subjected to testing. Here we test the two-species hypothesis using computer simulations to attempt to reproduce the unusual pattern of intrasexual and intersexual dental metric variation observed in the Lufeng postcanine dentition. Conditions of the simulation experiments were optimized to favor the two-species hypothesis. It was found that, although the Lufeng pattern of metric variation could be reproduced by sampling two species, the likelihood of this occurrence was very low even when the conditions were optimized to the point of improbability. We conclude that the likelihood is very high that the Lufeng sample is composed of one species that is more highly sexually dimorphic in the postcanine dentition than any extent primate species. If so, then the high levels of sexual dimorphism and intraspecific dental metric variation in this species violate the central assumption of methods that employ the coefficient of variation (CV) for paleotaxonomy, namely, that neither can lie outside the ranges observed among extant species. Thus, we further conclude that the CV must be used with caution when evaluating the taxonomic composition of fossil samples and, further, that it cannot be used to falsify a single-species hypothesis in any meaningful way. Other fossil hominoid samples with high measures of dental variation may indicate that considerable sexual size dimorphism typified many Eurasian middle–late Miocene hominoids.