The effects of ecology and evolutionary history on robust capuchin morphological diversity.

Recent molecular work has confirmed the long-standing morphological hypothesis that capuchins are comprised of two distinct clades, the gracile (untufted) capuchins (genus Cebus, Erxleben, 1777) and the robust (tufted) capuchins (genus Sapajus Kerr, 1792). In the past, the robust group was treated as a single, undifferentiated and cosmopolitan species, with data from all populations lumped together in morphological and ecological studies, obscuring morphological differences that might exist across this radiation. Genetic evidence suggests that the modern radiation of robust capuchins began diversifying ∼2.5 Ma, with significant subsequent geographic expansion into new habitat types. In this study we use a morphological sample of gracile and robust capuchin craniofacial and postcranial characters to examine how ecology and evolutionary history have contributed to morphological diversity within the robust capuchins. We predicted that if ecology is driving robust capuchin variation, three distinct robust morphotypes would be identified: (1) the Atlantic Forest species (Sapajus xanthosternos, S. robustus, and S. nigritus), (2) the Amazonian rainforest species (S. apella, S. cay and S. macrocephalus), and (3) the Cerrado-Caatinga species (S. libidinosus). Alternatively, if diversification time between species pairs predicts degree of morphological difference, we predicted that the recently diverged S. apella, S. macrocephalus, S. libidinosus, and S. cay would be morphologically comparable, with greater variation among the more ancient lineages of S. nigritus, S. xanthosternos, and S. robustus. Our analyses suggest that S. libidinosus has the most derived craniofacial and postcranial features, indicative of inhabiting a more terrestrial niche that includes a dependence on tool use for the extraction of imbedded foods. We also suggest that the cranial robusticity of S. macrocephalus and S. apella are indicative of recent competition with sympatric gracile capuchin species, resulting in character displacement.

Feeding and resting postures of wild northern muriquis (Brachyteles hypoxanthus).

Increased body size in Brachyteles has been regarded as an important evolutionary adaptation that allowed a greater reliance on leaves compared to other more frugivorous Atelidae, but its association with muriqui positional behavior and substrate use is still unknown. Here, we present original data on the feeding and resting postures of the northern muriqui (Brachyteles hypoxanthus) and evaluate predictions about the relationships between body size, postural behavior, and substrate use derived from previously published data for other atelids (e.g. Alouatta, Ateles, and Lagothrix). The study was undertaken from August 2002 to July 2003 on a large group of well-habituated muriquis inhabiting the Reserva Particular do Patrimônio Natural - Felíciano Miguel Abdala in Minas Gerais, Brazil. Consistent with our predictions, we found that B. hypoxanthus was highly suspensory during postural feeding (60.9%) and commonly used tail-hind limb suspension/horizontal tripod (38.0%) or tail-forelimb/hind limb suspension (21.4%). However, although tail-suspensory postures permitted the muriquis to use the terminal canopy and small-sized substrates, these areas were also accessed via tail-assisted above-branch postural behaviors involving multiple substrates. Unexpectedly, tail-suspensory postures were found to be frequently associated with large substrates, tree trunks, and the understory. We suggest that Brachyteles' ability to access food resources from all areas of a feeding tree and from tree crowns at different canopy levels may account for their ability to efficiently exploit food resources in seasonal disturbed forest fragments of the Brazilian Atlantic Forest today.

Widespread survey finds no evidence of Haplosporidium nelsoni (MSX) in Gulf of Mexico oysters.

The advent of molecular detection assays has provided a set of very sensitive tools for the detection of pathogens in marine organisms, but it has also raised problems of how to interpret positive signals that are not accompanied by visual confirmation. PCR-positive results have recently been reported for Haplosporidium nelsoni (MSX), a pathogen of the oyster Crassostrea virginica in 31 of 40 oysters from 6 sites in the Gulf of Mexico and the Caribbean Sea. Histological confirmation of the PCR results was not undertaken, and no haplosporidian has been reported from the numerous histological studies and surveys of oysters in the region. To further investigate the possibility that H. nelsoni is present in this region, we sampled 210 oysters from 40 sites around the Gulf of Mexico and Puerto Rico using PCR and 180 of these using tissue-section histology also. None of the oysters showed evidence of H. nelsoni by PCR or of any haplosporidian by histology. We cannot, therefore, confirm that H. nelsoni is present and widespread in the Gulf of Mexico and the Caribbean Sea. Our results do not prove that H. nelsoni is absent from the region, but taken together with results from previous histological surveys, they suggest that for the purposes of controlling oyster importation, the region should continue to be considered free of the parasite.

Dentition of moustached tamarins (Saguinus mystax mystax) from Padre Isla, Peru, part 1: quantitative variation.

Analyses of dental variation in geographically restricted, wild populations of primates are extremely rare; however, such data form the best source for models of likely degrees of variation within and between fossil species. Data from dental casts of a geographically restricted population of moustached tamarins (Saguinus mystax mystax) from Padre Isla, Peru, document high levels of dental variability, as measured by coefficients of variation, in a nonsexually dimorphic species, despite its isolation and small population size. Like other primates, moustached tamarins show lower variability in the dimensions of the first molars and increased variability in the dimensions of the final molars in the toothrow. Moustached tamarins from Padre Isla have a distinctive pattern of variability in the remaining teeth, including more stable tooth lengths in the anterior and posterior portions of the toothrow, and more stable tooth widths in the midregion of the toothrow. High variability in incisor width may be due to age effects of a distinctive diet and pattern of dental wear.

A randomized clinical trial of feeder vessel photocoagulation of proliferative sickle cell retinopathy. I. Preliminary results

A randomized prospective clinical trial of feeder vessel photocoagulation for proliferative sickle cell retinopathy was performed. In Chicago, there were 34 argon laser-treated eyes and 30 control eyes. In Kingston, there were 53 xenon arc treated eyes and 50 control eyes. Prolonged loss of visual acuity was rare in both photocoagulated and control eyes. Argon laser and xenon arc feeder vessel photocoagulation reduced the incidence of vitreous hemorrhage and visual loss from vitreous hemorrhage. However, photocoagulation was associated with an increased risk of choroidal neovascularization (xenon arc greater than argon laser) and retinal detachment (argon laser), although visual loss from these complications has not been in these patients so far. (AU)

Macular vasculature, visual acuity, and irreversibly sickled cells in homozygous sickle cell disease

Observations of visual acuity and the conjunctival, macular, and perimacular vascularity have been assessed in patients with homozygous sickle cell (SS) disease. There were 17 matched pairs, each consisting of one patient with a high count (>15 percent) and one with a low count (<5 percent) of irreversibly sickled cell (ISCs). The macular vascular bed was assessed by measurements of the foveal avascular zone (FAZ), perimacular zones, and counts of perimacular vascular abnormalities (perimacular counts). Small foveal avascular zones and high perimacular counts were commoner in younger than older patients and there was a significant inverse correlation between size of the FAZ and the perimacular count. These observations were compatible with the hypothesis that perimacular vessel anomalies represent the early vaso-occlusive phase which progresses to ischaemia and the formation and enlargement of avascular areas. Visual acuity was assessed by Snell's test type and by measuring contrast sensitvity. There was no obvious relationship between acuity measured by the 2 methods and no relationship between acuity and observations of mascular vascularity. High ISC counts were significantly related to abnormalities of conjunctival vasculature, but no relationship was noted with abnormalities of the macular vasculature or with visual acuity (AU)

Angioid streaks in Jamaican patients with homozygous sickle cell disease

Angioid streaks were observed in 21 of 242 patients with homozygous sickle cell disease. Two morphological types were observed. There is no evidence that angioid streaks in Jamaican patients are related to pseudoxanthoma elasticum (AU)

Choroidal neovascularisation induced by photocoagulation in sickle cell disease

Choroidal neovascularisation occurred in 35 out of 57 (61 percent) patients during a trial of xenon arc photocoagulation in proliferative sickle retinopathy. Nineteen patients manifested abnormal vessel systems in the plane of the retina which tended to be benign, not enlarging and without complications (choroidoretinal neovascularization). In 16 patients the abnormal vessel system grew into the vitreous, tended to increase in size and to be associated with vitreous haemorrhage and retinal traction (choroidovitreal neovascularisation). Both forms of neovascularisation were significantly more common at younger ages. Treatment was generally unsatisfactory, frequently resulting in further enlargement of the lesions. Although the natural history of choroidal neovascularisation and its ultimate effect on visual function remains to be recorded, these lesions constitute a common and potentially serious complication of xenon arc photocoagulation in proliferative sickle retinopathy as currently performed. (Summary)