Natural hybrid zones between distinct species have been reported for many taxa, but so far, few examples involve carnivores or Neotropical mammals in general. In this study, we employed mitochondrial DNA (mtDNA) sequences and nine microsatellite loci to identify and characterize a hybrid zone between two Neotropical felids, Leopardus geoffroyi and L. tigrinus, both of which are well-established species having diverged from each other c. 1 million years ago. These two felids are mostly allopatric throughout their ranges in South America, with a narrow contact zone that includes southern Brazil. We present strong evidence for the occurrence of hybridization between these species and identify at least 14 individuals (most of them originating from the geographical contact zone) exhibiting signs of interspecific genomic introgression. The genetic structure of Brazilian L. tigrinus populations seems to be affected by this introgression process, showing a gradient of differentiation from L. geoffroyi correlated with distance from the contact zone. We also corroborate and extend previous findings of hybridization between L. tigrinus and a third related felid, L. colocolo, leading to an unusual situation for a mammal, in which the former species contains introgressed mtDNA lineages from two distinct taxa in addition to its own.

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A special case of the x-ray multiple diffraction phenomenon, the Bragg surface diffraction (BSD), has been investigated under lattice damage due to ion implantation in GaAs (001) samples. The BSD profile is very sensitive to the diffraction regime (dynamical or kinematical) and provides information regarding crystalline perfection and lattice strains in both directions—parallel and perpendicular—to the sample surface. Results from grazing-incidence x-ray diffraction and reciprocal space mapping are also reported.

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The intense exploitation since 1972 of the formerly only slightly exploited protogynous hermaphroditic fish Pagrus pagrus (L.) in southern Brazil has led in less than a decade to the collapse of the fishery, with no recovery four decades later. In this study we analized the age structure, growth, reproduction and mortality of the species were studied based on samples collected from 1976 to 1985 to provide a baseline before the onset of overexploitation. Maximum estimated ages were 21 and 26 years based on scale and otolith readings, respectively. Mean total length (TL) at age did not differ between males and females, while hermaphrodites were smaller. The von Bertalanffy growth coefficients for all fish (immature, females, hermaphrodites and males) were L∞ = 447 mm, k = 0.204 and t0 = −1.134 yr. Change in growth was observed during the study period. Females were dominant at all sizes, hermaphrodites were only present up to intermediate sizes, and males, despite being infrequent at small sizes, made up over 40% among the larger specimen (TL > 400 mm). Spawning took place mainly in late spring and condition factors were lower after spawning. Natural mortality was estimated as M = 0.173 yr−1 based on the von Bertalanffy growth parameters. Total mortality (Z) and exploitation rate (E) estimated from catch curves of fully recruited red porgies aged five to ten years increased from 0.24 yr−1 and 28% before 1973 to 0.49 yr−1 and 63% in the following years. Two distinct scale and otolith patterns, one with well-marked annuli and another with faint or absent annuli, suggested that the red porgy stock off southern Brazil might not be homogeneous and may include subpopulations that do not fully mix.

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We report the observation of a spatially-ordered bidimensional array of self-assembled InP quantum dots grown on slightly In-rich InGaP layers. The alignment of InP dots is observed along [100] and [010] directions. This effect is enhanced when 2° off vicinal substrates are used; it is also strongly dependent on growth temperature. Our results suggest that the density and size of CuPt-type atomically ordered regions as well as compositional modulation of InGaP layers play an important role on the spatial alignment of InP/InGaP quantum dots.