Biomedical subjects

R J Rhine

Publications and source records attributed to R J Rhine.

16 recordsLinked to original sources

PubMed2000

Lifetime reproductive success, longevity, and reproductive life history of female yellow baboons (Papio cynocephalus) of Mikumi National Park, Tanzania.

The relationship between longevity and lifetime reproductive success (LRS) was studied in free-ranging female baboons of Mikumi National Park, Tanzania. A severe population decline occurred between the 12th and 20th years of the study. The total sample consisted of 72 females born and reaching adulthood before the start of the population decline. There were 27 females who were adult at the start of the study and 45 who became adult within the 12 years prior to the decline. The subjects were studied until all 72 were dead and all of their offspring were either dead or at least six years old; this took 24 years. The relationship of longevity to LRS was statistically significant for the total sample and for both sub-samples, with 70% of the total variance in LRS accounted for by longevity. Longevity was linked to LRS via a chain of statistically significant relationships: The longer the life span, the longer the reproductive life; the longer the reproductive life, the more offspring produced; the more offspring produced, the higher the LRS. Mean LRS, life span, and reproductive longevity all differed between the two sub-samples. Since the sub-samples were time-linked to a population decline affecting longevity, either sub-sample separately would fail to reflect the broader picture. This illustrates the importance of appreciable sample sizes from long-term studies in helping understand the dynamics between life history estimates and ecological conditions in variable environments.

Animals↗

PubMed1999

Logical problems and misunderstandings in "Problems with dimensionless measurement models of synchrony in biological systems".

A model for the standardized measurement of synchrony in behavioral or biological states was proposed for use in comparative analyses of synchrony's adaptive significance. A recent critique attempts to discredit dimensionless (unitless) or standardized measures of synchrony in general and the proposed model in particular. Although the critique helps define and sharpen thinking about the measurement of synchrony and makes some well-taken points, it also arrives at questionable conclusions based upon dubious assumptions. The critique proceeds from a fictional example in which all biological states being considered always have exactly the same durations for all individuals and always start or end for all individuals at exactly the same instants in time. These unreal, biologically meaningless premises, together with other questionable assumptions, are the basis of inappropriate analyses of standardized measures. The critique's arguments reveal a failure to understand the basic underlying principle of the standardized method and are dependent upon faulty logic. A statistical discussion contains both worthy points and arguable comments based not on data or actual probabilities of real events but on irrelevant chance outcomes derived from the biologically meaningless assumptions. The critique's conclusions are not credible, and its basic question probably is not scientifically answerable.

Animals↗

PubMed1998

Validity of an estimator of reproductive success.

Lifetime reproductive success is a major component of individual fitness and a central dependent variable for the study of natural selection. For long-lived animals, such as apes or baboons, assessment of lifetime reproductive success requires observations of identified individuals in continuous, long-term studies from which it is difficult and often impossible to obtain an adequate sample of necessary reproductive and survival data. This situation can be alleviated by the availability of a valid measure that uses incomplete reproductive histories to estimate the lifetime reproductive success of individuals. The validity of one such estimator was tested by determining if, after 10.5 years of studying free-ranging female baboons, it predicted lifetime reproductive success obtained from full reproductive histories after 21.5 years. Validity was evaluated for seven criteria of success, ranging from the number of a female's live births to the number of her offspring that reached the age of 72 months. Moderate to good prediction of lifetime reproductive success by the estimator was found for criteria of offspring living to 36 months or more. After 10.5 years, complete reproductive life spans were available for only eight females. Using the estimator, analytic potential, via sample representativeness and size, was improved at 10.5 years by an increase from a sample of eight to between 34 and 62, depending upon the criterion used, and at 21.5 years from 39 to 70. With a valid estimator, the opportunity to study lifetime reproductive success of a long-lived species is substantially improved without having to depend upon rarely available, uninterrupted data collection for 20-60 years.

Animals↗

PubMed1997

Criteria of reproductive success.

To determine reproductive success, it is necessary for the researcher to specify a criterion of success, such as the number of a parent's offspring living to the age of reproduction. A measurement model, which includes the researcher's choice of criterion, has been proposed to estimate the lifetime reproductive success (R) of long-lived animals from complete or incomplete knowledge of the reproductive life histories of mothers and the survival fates of offspring. This research uses R and data from female baboons of Mikumi National Park, Tanzania, as vehicles to investigate the relationship between reproductive success and several criteria. Secondarily, it also investigates the relationship between R and the number and rate of offspring production. Seven criteria of reproductive success, ranging in 12-month increments form 0 (birth) to 72 months of offspring life, were applied to 10.5 years of reproductive data from 61 Mikumi females. Theoretically, the best scenario for comparative purposes is an invariant R across different criteria; however, the mean R systematically increased as the criteria increased. This is more an inconvenience than a serious problem because high correlations indicate high predictability between Rs from pairs of criteria. R was modestly correlated with the rate of offspring production, indicating that rate can be employed as a rough index of reproductive success. The choice of a criterion is a trade off between theory, practicality, the strength of the criterion, and the effect of the choice upon sample representativeness and size.

Animals↗

PubMed1987

Baboon diet: a five-year study of stability and variability in the plant feeding and habitat of the yellow baboons (Papio cynocephalus) of Mikumi National Park, Tanzania.

The habitat and plant feeding of 64 well-habituated, individually identified adult male and female yellow baboons was studied for 5 years at Mikumi National Park, Tanzania. Variation across the years showed that a study of only one or two years would have been incomplete and misleading. The list of baboon food species obtained from Mikumi is considerably larger and more diverse than any previously reported. One to six plant parts were eaten from each of more than 180 species. The 25 most common tree genera all contained species used for food. Of the 50 most common grass, shrub and herb genera, 93% included plant foods. Using months in which a species was eaten during at least one year of the study, 21 staple species were eaten during a mean of 8.86 months and 7 were eaten in all 12 months. Although many foods were from commonly available plant species, 15 such species were only rarely eaten. The number of parts of a species eaten per month and an estimate of the amounts eaten per month both varied with temperature and rainfall, being lowest near the end of the cool, dry season. There were substantial differences from year to year in the timing and amount of food production of many species; nevertheless, the same broad feeding pattern was repeated in each of the 5 years of the study. Despite yearly variation in food availability, 14 or more staples and other common foods were eaten in any given month. If crops of many of these foods were to fail, a large number of less commonly eaten species could be substituted. Baboons are eclectic feeders that appear to be optimizing their diet by selective feeding from among a wide array of available foods in an ever-changing floristic environment.

Animals↗

PubMed1986

Insect and meat eating among infant and adult baboons (Papio cynocephalus) of Mikumi National Park, Tanzania.

It has been suggested that baboon predation upon vertebrates may tend to peak in the dry season because insect food is then less available, and that males obtain animal nutrients primarily from vertebrates whereas other troop members obtain them primarily from invertebrates. The development of meat and insect eating by 22 male and 24 female infants studied for 25 months was compared with that of 18 male and 46 female adults studied for 37 months. Systematic sampling allowed quantitative comparisons between meat and insect eating, infants and adults, and males and females. Infants ate no meat, but their insect eating began early and increased steadily during the first year of life. In comparison with insect foods, meat was a minor ingredient of the adult's diet. Insect eating occurred less during dry than during rainy months, but meat eating was spread across the year. Reliable sex differences in insect eating did not occur. The findings were related to theories offered to explain the attractiveness of animal foods to primates and to the suggestion that a sex difference in predatory inclinations of hominid ancestors may have been a preadaptation underlying the eventual emergence of male hunting and female gathering.

Aging↗

PubMed1981

Adult male positioning in baboon progressions: order and chaos revisited.

Evidence of nonrandom positioning among adult males is crucial for a protection theory of the spatial organization of baboon progressions. In a recent study it was suggested that systematic positioning of troop members other than mothers and infants is so slight and rare that progressions may be regarded as essentially random. This suggestion depends upon debatable methodological points presumably downgrading previous findings of nonrandom order. Reanalysis of data from this study revealed numerous analytical and statistical problems, as well as serious calculation and other errors, and showed that the findings are consistent with results of the present and previous research. Adult males tended toward the front or back of progressions, a tendency which was intensified in potentially dangerous situations. Dominant males were disproportionately more often frontward and subordinate males rearward. Nonrandom order, which was found for a variety of circumstances at high levels of statistical significance, was unusually general in that it occurred in 6 studies, 7 troops, 2 species, and 5 locations. Such generality is consistent with a protection theory postulating phylogenetic underpinnings of a sociospatial organization which allows an advanced primate to adapt to terrestrial coexistence with predators.

Animals↗

PubMed1979

Weights and heights of stump-tailed macaques (Macaca arctoides) living in colony groups.

Weights and heights of adults, week-old infants, and animals of intermediate ages were obtained from colony groups of stump-tailed macaques and are compared with similar measurements of rhesus, Japanese macaques, and other stump-tailed monkeys.

Aging↗

PubMed1978

The nature of a primary feeding habit in different age-sex classes of yellow baboons (Papio cynocephalus).

Two feeding habits of 30 baboons selected equally from five age-sex classes were studied at Mikumi National Park, Tanzania. The finding, gathering, and preparing of sedge corms and of seeds of tamarind fruit were described in detail. Adults obtained these foods faster than younger animals, although even small juveniles and weaned infants were efficient in gathering and preparing them. While gathering sedges or tamarinds, adult males sat in one place longer than others and obtained more food per sitting. Adults ate more pieces of food per minute than juveniles, but adult rates of eating did not differ by sex. The adult rate of food intake was inconsistent with the assumption of different food requirements for males and females of a species with pronounced sexual dimorphism.

Age Factors↗

PubMed1975

The order of movement of yellow baboons (Papio cynocephalus).

The spatial organization of progressing baboons is thought to serve a protective function considered important in their adaptation to a terrestrial existence. Progression positions of identified black infants, adult males, and other yellow baboons were determined from repeated samples of troop movements. Spatial positioning by demographic class was similar to that previously found for three troops of anubis baboons living in two different habitats. Such consistency across species and habitats seems unlikely unless it arises from a common genetic background or common ontogenetic stabilizing mechanism.

Age Factors↗

PubMed1972