TESTS FOR ANCIENT SPECIES FLOCKS BASED ON MOLECULAR PHYLOGENETIC APPRAISALS OF SEBASTES ROCKFISHES AND OTHER MARINE FISHES

The concept of species flocks has been central to previous interpretations of patterns and processes of explosive species radiations within several groups of freshwater fishes. Here, molecular phytogenies of species-rich Sebastes rockfishes from the northeastern Pacific Ocean were used to test predictions of null theoretical models that assume random temporal placements of phylogenetic nodes. Similar appraisals were conducted using molecular data previously published for particular cichlid fishes in Africa that epitomize, by virtue of a rapid and recent radiation of species, the traditional concept of an intralacustrine “species flock.” As gauged by the magnitudes of genetic divergence in cytochrome b sequences from mitochondrial DNA, as well as in allozymes, most speciation events in the Sebastes complex were far more ancient than those in the cichlids. However, statistical tests of the nodal placements in the Sebastes phylogeny suggest that speciation events in the rockfishes were temporally nonrandom, with significant clustering of cladogenetic events in time. Similar conclusions also apply to an ancient complex of icefishes (within the Notothenioidei) analyzed in the same fashion. Thus, the rockfishes (and icefishes) may be interpreted as ancient species flocks in the marine realm. The analyses exemplified in this report introduce a conceptual and operational approach for extending the concept of species flocks to additional environmental settings and evolutionary timescales.     

MORPHOLOGICAL AND ECOLOGICAL STUDY OF PHYSODERMA DULICHII

A new species of aquatic Phycomycete, Physoderma dulichii Johns, parasitic on the aquatic sedge Dulichium arundinaceum (L.) Britt., is described from northern Michigan. This parasite infects and kills the upper epidermal cells of the host leaves. Macroscopically, infection by P. dulichii is indicated by striking brown bands with irregular margins, at intervals on the upper surfaces of the leaves. Like other species of Physoderma, this organism's development includes two distinct phases, an epibiotic monocentric phase producing asexual zoospores and an endobiotic polycentric phase bearing thick-walled resting spores that germinate after an extensive period of maturation at low temperature to form zoospores. The morphology and development of the two phases and of resting spore germination are reported in detail. Only the immature leaves of the host are susceptible to infection, which may be initiated by the introduction of mature resting spores, zoospores from germinated resting spores, or zoospores from epibiotic sporangia. Resting-spore zoospores may also produce the endobiotic stage directly. Initiation of infection in nature requires that the terminal cluster of immature leaves on the host plant be submerged, but infection of subsequently formed leaves of emergent culms can be accomplished through the agency of zoospores from epibiotic sporangia on older leaves. The relation of infected stands of hosts to their environment is discussed and the importance of standing water to infection noted. The geographical distribution of the parasite shows correlation with the drainage basins of the Great Lakes, the St. Lawrence River, and the northern Atlantic Coastal Plain     

Responses of rain-forest primates to habitat disturbance: A review

The survival of primates in moderately disturbed forests is determined by a complex of variables. Correlation analyses suggest that ecological features of a species may confer a basal survival ability but that details of the form of disturbance may be crucially important. Correlation analyses reveal that body size alone is a poor predictor of primate response to moderate forest disturbance. However, when the effects of diet variables are held constant, body size more strongly correlates with survival ability (smaller species surviving better). Degree of frugivory shows a significant negative correlation with survival ability at both univariate and multivariate levels of analysis. In contrast, dietetic diversity is not correlated with survival ability at either level of analysis. Together, body size and percentage frugivory explain 44% of the variation in species’ responses to moderate habitat disturbance. Idiosyncratic responses of species can usually be traced to specific features of the changing environment, such as selective elimination of important food sources and, conversely, the presence of increased densities of particular food sources arising from the disturbance.     

Leaky intra-acinar arteries in rat lungs perfused with hydrogen peroxide

We have investigated the effects of H2O2 (150 or 300 microM) on the ultrastructure and permeability of the pulmonary endothelium in rat lungs perfused for 60 min with buffered Hanks' bovine serum albumin medium. In one group of experiments, we examined the effect of H2O2 on the uptake and transport of cationized ferritin (CF) by endothelial cells in intra-acinar arteries, alveolar capillaries, and interlobular veins. The influence of the oxidant on endothelial adsorptive endocytic processes was assessed by measuring the density of ferritin particles in luminal vesicles, multivesicular bodies, and basal lamina. In a second group of experiments, we examined the effects of H2O2 on the fine structure and permeability to electron-dense macromolecules of arterial, microvascular, and venous endothelium. For this purpose, at the end of the 60-min perfusion with H2O2, CF was perfused to identify leaky vessels. We found that H2O2 caused a dose-dependent inhibition of transcytosis of CF in all vascular segments. At the lower dose of H2O2, inhibition of transcytotic activity was not associated with structural injury to the vascular endothelium or with elevation of wet-to-dry ratios. At the higher oxidant dose, inhibition of transcytosis was associated with leaky arterial endothelium and elevation of wet-to-dry ratios (6.44 +/- 0.12 vs. 5.64 +/- 0.16, P less than 0.02). The effects of H2)2 were prevented by adding catalase to the perfusate. The selective loss of structural integrity and leakiness of the arterial endothelium were diminished but not completely abolished by perfusing the oxidant retrograde from the venous side.(ABSTRACT TRUNCATED AT 250 WORDS)