Panmixia in Pocillopora verrucosa from South Africa

The genetic structure of six local collections of Pocillopora verrrucosa from six coral reefs in KwaZulu-Natal, South Africa, was examined using allozyme electrophoresis. The six separate reefs lie within two different reef complexes. Twenty-two enzymes were screened on five buffer systems, but only five polymorphic loci (Gpi-1, Gdh-1, Lgg-2, Lpp-1, Est-1) could be consistently resolved. No significant differences in allelic frequencies were detected among the six sites. All local collections were genotypically diverse, with evidence of only very limited clonal replication at each site. Indeed, the ratio of observed to expected genotypic diversity (mean Go:Ge=0.64 +/-0.05 SD), the ratio of observed number of genotypes to the number of individuals (mean Ng:N = 0.65 +/-0.04 SE), and deviations from the Hardy-Weinberg equilibrium indicate that sexual reproduction plays a major role in the maintenance of the populations. No genetic differentiation was found either within (FSR = 0.026 +/-0.003 SE) or between (FRT = 0.000 +/-0.001 SE) reef complexes. The homogeneity of the gene frequencies across the six reefs strongly supports the assumption that the KwaZulu-Natal reef complexes are highly connected by gene flow (Nem=44). The reefs in the southern and central reef complexes along the northern Maputaland coastline can therefore be considered part of a single population.

Carapace dentition patterns, morphometrics and allozyme differentiation amongst two toothed freshwater crab species (Potamonautes warreni and P-unispinus) (Decapoda : Brachyura : Potamonautidae) from river systems in South Africa

The taxonomic relationship between two toothed South African river crabs, Potamonautes warreni and P. unispinus, is unclear. The problem stems from the widespread variation in carapace dentition patterns amongst P. warreni individuals over its biogeographic range, where single toothed individuals may appear similar in carapace morphology to P. unispinus. Ten populations of P. warreni and 18 populations of P. unispinus were collected and the morphometric and genetic differentiation between the two taxa quantified. Patterns of morphometric and genetic variation were examined using multivariate statistics and protein gel electrophoresis, respectively. Principal component analyses of carapace characters showed that the two species are morphologically indistinguishable. However, discriminate functions analyses and additional statistical results corroborate the morphological distinction between the two taxa. Allozyme electrophoresis of 17 protein coding loci, indicated a close genetic similarity between the two species (I = 0.92). A fixed allelic difference at one locus (LT-2) and extensive genetic variability at another locus (PGM-1) indicate that two gene pools are present and that the two taxa are genetically isolated. Intraspecific genetic I values for both species were > 0.97 and indicated no apparent genetic structuring on a micro or macro-geographic scale. The variation in carapace dentition among P. warreni populations possesses no genetic basis and may possibly toe the product of ecogenesis. The value of dentition patterns in the systematics of river crabs is discussed. Dentition patterns among river crab species appear to be conserved and reliable as species specific diagnostic markers, but should ideally be used in combination with other morphological data sets and genetic evidence.

Determination of the hemispheric character (i.e. southern or northern latitudinal position) of equatorial ionosonde stations as deduced from long-term recordings of the minimum height of the F-region (h ' F)

The virtual (or minimum) height of the F-region (h'F), recorded over a number of solar cycles for I I equatorial and mid-latitude ionosonde stations, was used to deduce the hemispheric (i.e. southern or northern hemisphere) character of equatorial stations. The semi-annual median monthly height (h'F) variations consist of two components: major local summer maximum and winter sub-maximum (about 5 percent of the summer maximum). This hemispheric pattern was most consistently observed for equatorial stations (within 5degrees of the geomagnetic equator) in a period centred on the local midnight (21-03 LT) but was also present, to a lesser extent, at mid-latitude stations and at other time intervals. It is evident that the physical parameter h'F defines the hemispheric character of an equatorial station which has different (sometimes opposite) geographic and geomagnetic latitudes. There is a sharp transition in the latitudinal character of the stations on both sides of the equator leading to hypothesis that the equal maxima in h'F in December and June solstices are observed at a near-equator position labelled as ionosonde deduced equator (IDE). Such a signature was observed for an American equatorial (both geographic and geomagnetic) station Talara (Peru) which is an experimental support of the hypothesis. The IDE can be another useful parameter characterising the equatorial ionosphere. This finding reveals a new application of the standard ionosonde data in defining the geophysical character of equatorial stations, being an important contribution to space climatology. (C) 2002 Elsevier Science Ltd. All rights reserved.

The new Africa and Brazil in the Lula era: the rebirth of Brazilian Atlantic Policy

In the post-Cold War world, Africa has been an important focus of Brazilian foreign policy. Having a significant historical weight in building our nation, African countries are also part of the moves adopted by Brazil's foreign policy. The main purpose of the present text is to show this relevant regional dimension regarding Brazil's international insertion during the Lula era. The work is divided in two parts: the first part approaches Africa's international insertion throughout recent years and the second analyses the dimension occupied by African affairs in Brazil during the Lula era. The main argument is that the new role played by Africa in the international scene coincides with a global Brazil

A harder edge: reframing Brazil's power relation with Africa

Brazil's rapprochement with Africa during the last decade has been mostly explained as an attempt to improve political dialogue, raise economic interactions, and provide technical cooperation assistance. This article, however, argues that such framework does not sufficiently account for the use of Brazilian material resources in order to attain harder strategic goals towards the continent. By focusing on defense cooperation ties, it highlights an important niche in South-South relations that has also grown exponentially, with important consequences on how Brazil exerts power across the Atlantic.