Species delimitation is a major quest in biology and is essential for adequate management of the organismal diversity. A challenging example comprises the fish species of red snappers in the Western Atlantic. Red snappers have been traditionally recognized as two separate species based on morphology: Lutjanus campechanus (northern red snapper) and L. purpureus (southern red snapper). Recent genetic studies using mitochondrial markers, however, failed to delineate these nominal species, leading to the current lumping of the northern and southern populations into a single species ( L. campechanus ). This decision carries broad implications for conservation and management as red snappers have been commercially over-exploited across the Western Atlantic and are currently listed as vulnerable. To address this conflict, we examine genome-wide data collected throughout the range of the two species. Population genomics, phylogenetic and coalescent analyses favour the existence of two independent evolutionary lineages, a result that confirms the morphology-based delimitation scenario in agreement with conventional taxonomy. Despite finding evidence of introgression in geographically neighbouring populations in northern South America, our genomic analyses strongly support isolation and differentiation of these species, suggesting that the northern and southern red snappers should be treated as distinct taxonomic entities.

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We investigate the influence of mass inhomogeneities on the angular size-redshift test through a statistical analysis of angular size data for a large sample of milliarcsecond radio sources. The results are based on flat models driven by nonrelativistic matter plus a dark energy component in the form of a relic cosmological constant. To model the mass inhomogeneities we use the Zeldovich-Kantowski distance formula (also known as Dyer-Roeder distance redshift relation) which is characterized by the smoothness parameter α. Marginalizing over the characteristic angular size l and assuming a Gaussian prior on the matter density parameter, i.e., Ωm = 0.35 ± 0.07, the best fit model occurs at Ωm = 0.35 and α = 0.8. For an analysis without priors and minimizing χ 2 for the parameters l, Ωm and α we find that a conventional homogeneous scenario (α = 1) with Ωm = 0.2 and D = 22.6h −1 pc constitutes the best fit model for the present angular size data.

The Caribbean Red Snapper (Pargo) Lutjanus purpureus is the most economically important snapper in Brazil, which is sold, among other forms, as frozen fillets. During the process of transformation into fillets there is the removal of the distinctive morphological traits, being able to favor the substitution by less valued species. In addition, there is no national legislation requiring the insertion of the specific name on the product label. However, according to a Normative Instruction (IN N ° 29/2015 MAPA) that correlates the common and specific names of the products destined to the national trade, in Brazil only L. purpureus and L. campechanus can be denominated “Pargo”. Thus, the DNA barcode tool was used to identify the fillets sold in north of Brazil, labeled “Pargo”, with the aid of sequences from the public and control databases. The results showed that among 142 fillets examined, 78% was identified as L. purpureus and 22% as Rhomboplites aurorubens, a snapper with low commercial value in the country, revealing commercial fraud. The molecular identification method successfully used in this study to authenticate fillets snappers may also be used by surveillance authorities in the quality control of processed fish products, towards ensuring consumer rights.

The natural fiber market has been growing extraordinarily. Hereupon the current work presents the natural fiber of the periquiteira tree Cochlospermum orinocense of the Amazon forest. The chemical composition, physical aspects, morphology, thermal and mechanical properties of this fiber will be discussed. The thermal stability of the fiber samples was about 200 °C. The decomposition of cellulose and hemicelluloses in the fibers occurred at 300 ºC and above, while the degradation of the fibers happened above 400 °C. This fiber had good specific strength and good binding properties due to their low weight and presence of high cellulose (60.15wt.%), low lignin (12.03wt.%). More pronounced mass loss indicated the degradation of the amorphous regions of the cellulose, and finally reached a peak of approximately 390 °C.