Craniodental variation in the African macaque, with reference to various Asian species

Based on twenty-seven craniodental measurements and ratios derived from them, the relationship between the African macaque (M. sylvanus) and the others in Asia were examined with principal components analyses (PCA) and Euclidean distance analysis based upon prior discriminant function analyses (DFA). Results based on analyses of raw measurements indicate that the variation between species lies in the first axis of PCA; the species are dispersed according to their differences in size. The variation between sexes (sexual dimorphism) lies in the second axis. In the analyses of ratio variables, though these two patterns of separation remain orthogonal, they lie at approximately forty-five degrees to each axis. Variables relating to anterior teeth were found to play an important role in variation analysis, and this may be related to the special food preferences of these monkeys: more frequent usage of the incisor teeth for processing frugivorous diets than in other primates that are mainly folivorous. The results from Euclidean distance analyses indicate that the average distance of species within the Asian group is shorter than that between Asian and African groups regardless of sex and variable type. In addition the variation between African and Asian groups is larger than that within Asian group. Thus, it is reasonable to suggest that the African macaque has a range of measurements and ratios quite distinct from the species found in Asia (though the greatest separations result from the analyses of ratio data). These results therefore support the view that M. sylvanus may be regarded as an independent species group in the genus Macaca as proposed by Delson [1980].     

Craniodental Characters in the Taxonomy of Propithecus

The indriid genus Propithecus comprises the sifakas, medium-sized lemurs endemic to the forests of Madagascar. Traditionally, scientists divided the genus into only 2 or 3 species —Propithecus diadema, P. verreauxi, and, since 1988, P. tattersalli— with 4 or 5 subspecies in each of the first 2 taxa, but recent authors have suggested that many more distinct species should be recognized. We draw from quantitative and qualitative studies of craniodental traits to evaluate further the phenetic distinctiveness and taxonomic status of each named form of Propithecus. We recognize 9–10 species in the genus. The 4 or 5 species of the Propithecus diadema group —P. diadema, P. candidus, P. perrieri, P. edwardsi, and perhaps P. holomelas, if distinct— share several derived features, including large average body size and a mandible specialized for rotational chewing, and clearly comprise a closely related complex. The 5 species of the Propithecus verreauxi group —P. verreauxi, P. coquereli, P. deckenii, P. coronatus, P. tattersalli— are each highly distinctive morphologically and likely do not comprise a monophyletic group. In particular, we point out the highly distinctive cranial features of Propithecus coronatus, which researchers have traditionally largely overlooked.     

Correlates of Complete Childhood Vaccination in East African Countries

Background

Despite the benefits of childhood vaccinations, vaccination rates in low-income countries (LICs) vary widely. Increasing coverage of vaccines to 90% in the poorest countries over the next 10 years has been estimated to prevent 426 million cases of illness and avert nearly 6.4 million childhood deaths worldwide. Consequently, we sought to provide a comprehensive examination of contemporary vaccination patterns in East Africa and to identify common and country-specific barriers to complete childhood vaccination.

Methods

Using data from the Demographic and Health Surveys (DHS) for Burundi, Ethiopia, Kenya, Rwanda, Tanzania, and Uganda, we looked at the prevalence of complete vaccination for polio, measles, Bacillus Calmette–Guérin (BCG) and DTwPHibHep (DTP) as recommended by the WHO among children ages 12 to 23 months. We conducted multivariable logistic regression within each country to estimate associations between complete vaccination status and health care access and sociodemographic variables using backwards stepwise regression.

Results

Vaccination varied significantly by country. In all countries, the majority of children received at least one dose of a WHO recommended vaccine; however, in Ethiopia, Tanzania, and Uganda less than 50% of children received a complete schedule of recommended vaccines. Being delivered in a public or private institution compared with being delivered at home was associated with increased odds of complete vaccination status. Sociodemographic covariates were not consistently associated with complete vaccination status across countries.

Conclusions

Although no consistent set of predictors accounted for complete vaccination status, we observed differences based on region and the location of delivery. These differences point to the need to examine the historical, political, and economic context of each country in order to maximize vaccination coverage. Vaccination against these childhood diseases is a critical step towards reaching the Millennium Development Goal of reducing under-five mortality by two-thirds by 2015 and thus should be a global priority.     

Life-History Correlates of Placental Structure in Eutherian Evolution

The eutherian placenta shows remarkable evolutionary plasticity. To date, however, success in identifying selection pressures behind the observed diversity of placental structures has been limited. Evolutionary convergence among definitive placental morphologies and between placental morphologies and life-history variables can be used to suggest functions of derived aspects of placentation. In this paper, we use, for the first time, a comprehensive phylogenetic comparative approach to map phenotypic character states of both placental morphologies and life-history characteristics of species onto hypotheses of phylogenetic relationships in Eutheria. We employ phylogenetic methods for ancestral reconstruction, mutational mapping, and association analysis to resolve associations between five aspects of placental structure and to identify dominant combinations, or syndromes, of placental morphology. We map twenty life-history characters onto the eutherian phylogeny to examine how they correlate, over evolutionary time, with the multivariate diversification of placental structures. We identify two distinct eutherian constellations, based on associations between life-history and placental structure, which broadly reflect a dichotomy between slow and fast life-history strategies. In addition, we suggest that the observed association between placental invasiveness and group size is indicative of the effect of social behavior on the utility of genomic-imprinting in eutherian evolution.     

Evolution in indigenous west African rice

The genus Oryza contains two cultivated species,O. sativa L., the Asiatic rice, andO. glaberrima Steud. which is limited to Africa. Despite much taxonomic work on the relationships of the wild species of the genus, they are still imperfectly known and there has not been unanimous agreement on nomenclature. Most of the species group into complexes the delimitation of which is a matter of opinion. This paper presents results from experimental work, and a theory for the evolution of African cultivated rice is put forward based on taxonomic studies.     

Evolution of satellite DNA sequences in two tribes of Bovidae: A cautionary tale

Two clones, Bt1 from Bos taurus and Om1 from Ovis orientalismusimon, were used as probes for hybridization on genomic DNA and onmetaphase chromosomes in members of Bovini and Caprini tribes. Bt1 and Om1 aresequences respectively belonging to the 1.715 and 1.714 DNA satellite I families.Southern blots and fluorescence in situ hybridization experimentsshowed completely coherent results: the Bovini probe Bt1 hybridized only to membersof the Bovini tribe and not to members of Caprini. Likewise, the Caprini probe Om1hybridized only to members of the Caprini tribe and not to members of Bovini.Hybridization signals were detected in the heterochromatic regions of everyacrocentric autosome, except for two pairs of autosomes from Caprahircus that did not show hybridization to probe Om1. No signal wasdetected on X and Y chromosomes or on bi-armed autosomes. Remarkably, probe Om1showed almost 100% homology with a bacterial sequence reported inHelicobacter pylori.     

Craniodental biomechanics and dietary toughness in the genus Cebus

The tufted capuchin (Cebus apella) has been used in a number of comparative studies to represent a primate with craniofacial morphology indicative of hard-object feeding. Researchers have specifically referred to the tufted capuchin as a seed predator. Craniofacial features exhibited by the tufted capuchin, such as thick cortical bone in the mandibular corpus and symphysis, and a broad face associated with large masticatory muscles, permit the production and dissipation of relatively high masticatory forces. These morphologies, however, cannot distinguish between the tufted capuchin's propensity to exert higher forces when opening food with its anterior dentition or with its cheek teeth. It is also unclear whether these are adaptations for biting or chewing foods. This study uses a constrained lever model to compare the masticatory adaptations of C. apella to other cebids and atelids. Results show that the temporalis and masseter muscles in C. apella and C. olivaceus are more anteriorly positioned relative to nine other platyrrhine taxa. This condition, which appears to be ancestral among the Cebinae, increases force production at the incisors and canines while compromising third molar function. Cebus apella, has exaggerated this pattern. Field data on dietary toughness show that both capuchins typically select foods of low toughness, but on occasion, C. apella ingests food items of exceptional toughness. Thus, C. apella appears to maintain these biomechanical relationships by producing particularly high but relatively infrequent bite forces, particularly at the incisors and canines. However, adaptations for anterior dental use do not tightly constrain the diet of Cebus apella. This approach can be used to clarify the dietary adaptations of fossil taxa.     

Male-specific repeats in wild Bovidae

In this study, we investigated repetitive sequences localized on Y chromosomes. Repetitive DNA sequences represent a substantial part of the eukaryotic genome and, among them, a large portion comprises sequences repeated in tandem. Efficient and rapid isolation of repeat units is possible due to a laser microdissection technique used for Y chromosome separation, followed by polymerase chain reaction (PCR), cloning, and sequence analysis. We applied the derived repeat units to members of nine tribes within the Bovidae. Apart from the Y chromosomes of Bos taurus and Bubalus bubalis, where we used known sequences of repetition, the derived sequences were used as probes for fluorescent in situ cross-hybridization to members of the nine tribes of the Bovidae. We investigated the distribution of repeat units within the tribes and their localization on the Y chromosome. Sharing of sequence variants would indicate common descent, while the rapid horizontal evolution should allow discrimination between closely related species or subspecies.     

Correlates of Research Effort in Carnivores: Body Size,Range Size and Diet Matter

Given the budgetary restrictions on scientific research and the increasing need to better inform conservation actions, it is important to identify the patterns and causes of biases in research effort. We combine bibliometric information from a literature review of almost 16,500 peer-reviewed publications on a well-known group of 286 species, the Order Carnivora, with global datasets on species'' life history and ecological traits to explore patterns in research effort. Our study explores how species'' characteristics influenced the degree to which they were studied (measured as the number of publications). We identified a wide variation in intensity of research effort at both Family and Species levels, with some of the least studied being those which may need protection in future. Our findings hint at the complex role of human perspectives in setting research agendas. We found that better-studied species tended to be large-bodied and have a large geographic range whilst omnivory had a negative relationship with research effort. IUCN threat status did not exhibit a strong relationship with research effort which suggests that the conservation needs of individual species are not major drivers of research interest. This work is the first to use a combination of bibliometric analysis and biological data to quantify and interpret gaps in research knowledge across an entire Order. Our results could be combined with other resources, such as Biodiversity Action Plans, to prioritise and co-ordinate future research effort, whilst our methods can be applied across many scientific disciplines to describe knowledge gaps.     

Diet selection of African elephant over time shows changing optimization currency

Multiple factors determine diet selection of herbivores. However, in many diet studies selection of single nutrients is studied or optimization models are developed using only one currency. In this paper, we use linear programming to explain diet selection by African elephant based on plant availability and nutrient and deterrent content over time. Our results indicate that elephant at our study area maximized intake of phosphorus throughout the year, possibly in response to the deficiency of this nutrient in the region. After adjusting the model to incorporate the effects of this deficiency, elephant were found to maximize nitrogen intake during the wet season and energy during the dry season. We reason that the increased energy requirements during the dry season can be explained by seasonal changes in water availability and forage abundance. As forage abundance decrease into the dry season, elephant struggle to satisfy their large absolute food requirements. Adding to this restriction is the simultaneous decrease in plant and surface water availability, which force the elephant to seek out scarce surface water sources at high energy costs. During the wet season when food becomes more abundant and energy requirements are satisfied easier, elephant aim to maximize nitrogen intake for growth and reproduction. Our study contributes to the emerging theory on understanding foraging for multiple resources.     

Chromosome conservation in the Bovidae.

The chromosomes of 12 bovid species were harvested from fibroblast cultures after incorporation of bromodeoxyuridine into early replicating DNA. Q-band karyotypes were constructed, and, when possible, autosomal arms were numbered according to the cattle standard karyotype. Diploid chromosome number ranged from 30 to 60, yet, based on band similarity, chromosome-arm homologies were extensive. Employing the cattle karyotype as the standard, autosomal-arm differences indicative of possible syntenic disruption were noted for only chromosomes 3, 9, and 14. While chromosome-arm homologies were extensive, shared homologous biarmed chromosomes were rare. The commonness of monobrachially homologous biarmed chromosomes among some bovids (e.g., Antilopinae) suggested that reproductive isolation and speciation in some instances might have resulted from centric fusion events.     

Methemoglobin reductase in three species of Bovidae

Isoelectric focusing of red cell hemolysates revealed several isozymes that stain for NADH-methemoglobin reductase. Evidence for two different genetic loci controlling the banding patterns was obtained. One locus controlled a single band present in all animals tested. The second locus controlled ten different banding patterns that could be accounted for by four codominant alleles. Band B occurred in Bison bison. Bands A and C occurred in Bos indicus and band D occurred in both Bos indicus and Bos taurus. Bands A, C, and D were not observed in Bison bison and bands A, B, and C were not observed in Bos taurus.     

Feeding,Diet, and Jaw Form in West African Colobus and Procolobus

The functional link between mandibular morphology and masticatory stress has been documented by both experimental and comparative investigation. Somewhat more tenuous is the purported connection between dietary variation and the form of the jaws in primates. Several factors complicate the inference of such a connection, including anecdotal or incomplete dietary data from field studies and allometric effects on skeletal form that may have little to do with diet per se. We compared the jaws of sympatric colobines from West Africa to test the effect of diet on mandibular form. Procolobus badius and Colobus polykomos occupy the same habitat yet differ in diet primarily due to the exploitation of hard seeds by C. polykomos. The fact that the two taxa are comparable in body size also obviates the need for allometric qualifications. Colobus polykomos is expected to possess more robust mandibular corpora than Procolobus badius. In fact, the jaws of Colobus polykomos do not differ consistently from those of Procolobus badius in terms of biomechanical function. This apparent failure of mandibular morphology to reflect differences in diet and feeding behavior may be due to a variety of factors. We suspect that functional demands related to canine tooth support are contributing to obliteration of the expected biomechanical signal. Successful prediction of dietary effects on mandibular form requires consideration of competing structural and functional demands. The influence of diet on mandibular corporeal morphology is not equivalent across different primate species.