Thermal ecology,activity pattern,habitat, and microhabitats used by the skink Mabuya arajara (Squamata: Scincidae) in the Araripe Plateau,northeastern Brazil

ABSTRACT

We evaluated the activity period, thermal ecology, habitats, and preference for microhabitats of the skink Mabuya arajara in a humid forest environment on the slope of the Araripe Plateau, Brazil. A total of 283 lizards were observed. The lizards were found to be diurnally active (unimodal type pattern), with peak activity during the hottest hours of the day (1100 to 1200). About habitat use, the majority of individuals (73.8% N = 209) were recorded in the narrow transitional area, in the edges of the forest; while 26.4% of individuals were observed in open areas and no observations were made in dense forest. Seven different types of microhabitats were used, with fallen palm leaves (Arecaceae) being the preferred (47.7% N = 135). Considering all lizards, microhabitat niche breadth was 3.27. Males and females presented a high overlap (0.95) in microhabitat use. The average T_c recorded for M. arajara was 32.06 ± 2.72°C. Body size (SVL) did not influence body temperature (F = 0.51, P = > 0.05). Most of the animals were observed with their bodies completely exposed (67.84%, N = 192), 18.37% (N = 52) were semi-exposed and 13.79% (N = 39) were in shelters. Among animals with some degree of sunlight exposure, 57.59% (N = 163) were in shadows, 25.10% (N = 71) were under sunlight filtered by vegetation, and 17.31% (N = 49) were under direct sunlight.A review of the ecology of Mabuya spp. shows that several features appear to be conserved among members of the genus.     

Seriation in the Presence of Errors: NP-Hardness of <Emphasis Type="Italic">l</Emphasis><Subscript><Emphasis Type="Italic">∞</Emphasis></Subscript> -Fitting Robinson Structures to Dissimilarity Matrices

In this paper, we establish that the following fitting problem is NP-hard: given a finite set X and a dissimilarity measure d on X (d is a symmetric function from X ² to the nonnegative real numbers and vanishing on the diagonal), we wish to find a Robinsonian dissimilarity d _R on X minimizing the l _∞ -error ||d − d _R || _∞ = max_x,y ∈X{|d(x, y) − d _R (x, y)|} between d and d _R . Recall that a dissimilarity d _R on X is called monotone (or Robinsonian) if there exists a total order ≺ on X such that x ≺ z ≺ y implies that d(x, y) ≥ max{d(x, z), d(z, y)}. The Robinsonian dissimilarities appear in seriation and clustering problems, in sparse matrix ordering and DNA sequencing.     

Algal populations in Bottle Hollow Reservoir, Duchesne County, Utah

Bottle Hollow Reservoir contains a diverse algal flora. A total of 289 taxa was observed, 227 of which were diatoms. Both littoral and planktonic communities had high diatom diversity. During summer months filamentous Chlorophvta were diverse and high in biomass in the littoral zone. Phytoplankton collections in Bottle Hollow Reservoir were dominated by four species: Asterionella formosa, Cyclotella comta, Dinobryon divergens, and Fragilaria crotonensis. Plankton samples contained mostly small diatoms in early spring, with larger algae succeeding these as the summer progressed. No blue - green algae were important in this succession. Two peak production periods were observed, one in the fall and one in the spring. Bottle Hollow Reservoir appears to be a healthy mesotrophic system based on the evidences of moderately high algal diversity, insignificance of blue-green algae, and the presence of a suite of diatom species indicative of mesotrophic conditions.     

Factors influencing fish assemblages of a high-elevation desert stream system in Wyoming

Seven fish species were found in the Bitter Creek drainage of southwest Wyoming, but only speckled dace ( Rhinichthys osculus ), flannelmouth sucker ( Catostomus latipinnis ), and mountain sucker ( Catostomus platyrhynchus ) were indigenous. No relationships were found between fish standing stocks and habitat features, but species richness was related to elevation and stream width. No fish were found above an elevation of 2192 m. Only the most downstream study read had more than three species present. Two indigenous species, speckled dace and mountain sucker, and a nonnative species, fathead minnow ( Pimephales promelas ), were predominant fishes in the drainage. These three species withstand intermittent stream flows that are common in the drainage.     

β-Chitin/Chitosan Obtained from Loligo and Humboldt Squids Effectiveness as Wound Dressing Material

A number of materials are utilized to develop wound care dressing materials with metallic treatments such as ionic silver and zinc. Metallic ions if used for a prolonged time may lead to toxicity. Alternatively chitin,a natural polysaccharide found in nature, is utilized. It is found in fungi, crabs, mushrooms,squids, octopus, and many other living organisms. Chitin has similar structure to cellulose but its deacetylated derivate chitosan has amine groups that provide potential antibacterial properties along with a number of other advantages. Chitin in its natural form is found in three different structural forms,namely α,β,and γ.The β-chitin and chitosan are mostly found in the exoskeleton of squids. Loligo and Humboldt squids were studied. It is anticipated that Humboldt chitin is more effective in serving as antibacterial material and can be utilized for wound care. Differences in steriochemical structure were observed among β-chitin structures obtained and amine group’s presences were found along with ability of materials to swell.     

Embryology: does prepatterning occur in the mouse egg?

A recurring question in developmental biology has been whether localized determinants play any role in mammalian preimplantation development. This is a controversial issue that brings back the idea of prepatterning and is explored further by Plusa et al., who claim it is the first cleavage of the mouse zygote that predicts the blastocyst axis, rather than the animal pole or sperm entry point, as previously suggested. However, other evidence indicates that the blasotcyst axis is not predetermined and there is no prepatterning in the mouse egg. Here we investigate the origin of these different views and conclude that they arise from differences in the data themselves and in their interpretation.     

Insights into the dynamics of mantle plumes from uranium-series geochemistry

The long-standing paradigm that hotspot volcanoes such as Hawaii or Iceland represent the surface expression of mantle plumes--hot, buoyant upwelling regions beneath the Earth's lithosphere--has recently been the focus of controversy. Whether mantle plumes exist or not is pivotal for our understanding of the thermal, dynamic and compositional evolution of the Earth's mantle. Here we show that uranium-series disequilibria measured in hotspot lavas indicate that hotspots are indeed associated with hot and buoyant upwellings and that weaker (low buoyancy flux) hotspots such as Iceland and the Azores are characterized by lower excess temperatures than stronger hotspots such as Hawaii. This direct link between buoyancy flux and mantle temperature is evidence for the existence of mantle plumes.     

Historical phenology: grape ripening as a past climate indicator

French records of grape-harvest dates in Burgundy were used to reconstruct spring-summer temperatures from 1370 to 2003 using a process-based phenology model developed for the Pinot Noir grape. Our results reveal that temperatures as high as those reached in the 1990s have occurred several times in Burgundy since 1370. However, the summer of 2003 appears to have been extraordinary, with temperatures that were probably higher than in any other year since 1370.     

Perennial water ice identified in the south polar cap of Mars

The inventory of water and carbon dioxide reservoirs on Mars are important clues for understanding the geological, climatic and potentially exobiological evolution of the planet. From the early mapping observation of the permanent ice caps on the martian poles, the northern cap was believed to be mainly composed of water ice, whereas the southern cap was thought to be constituted of carbon dioxide ice. However, recent missions (NASA missions Mars Global Surveyor and Odyssey) have revealed surface structures, altimetry profiles, underlying buried hydrogen, and temperatures of the south polar regions that are thermodynamically consistent with a mixture of surface water ice and carbon dioxide. Here we present the first direct identification and mapping of both carbon dioxide and water ice in the martian high southern latitudes, at a resolution of 2 km, during the local summer, when the extent of the polar ice is at its minimum. We observe that this south polar cap contains perennial water ice in extended areas: as a small admixture to carbon dioxide in the bright regions; associated with dust, without carbon dioxide, at the edges of this bright cap; and, unexpectedly, in large areas tens of kilometres away from the bright cap.