Early post-breakup kinematic adjustments of continental-oceanic transform fault zones; Cape Range, Coromandal and Romanche transform margin case study

A comparison of transform margins that started their evolution as continental transforms shows differences in their tectonic style, which can be attributed to the variable kinematic adjustments they underwent during the post-breakup continental-oceanic stage of their development. Three end-member examples are presented in detail. The Cape Range transform fault zone (Western Australia) retained its strike-slip character during its entire continental-oceanic stage, as documented by the transform-perpendicular system of spreading-related magnetic stripe anomalies. The Coromandal transform fault zone (Eastern India) adjusted its kinematics to a transtensional one during its continental-oceanic stage, as indicated by the transform-oblique system of magnetic stripe anomalies and extensional component of movement indicated by a narrow zone of crustal thinning. The Romanche transform fault zone (Equatorial Africa) adjusted its kinematics to transpressional, as documented by the changing geometries of magnetic stripe anomalies and transpressional folding during its continental-oceanic development stage. Based on the recognition of the aforementioned adjustments, we suggest a new categorization of transforms into (1) those that experience transpressional adjustment, (2) those that experience transtensional adjustment and (3) those that do not experience any adjustment during their continental-oceanic development stage.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5762388

Mapping the complexity of Transform Margins

Transform margins are a function of the pre-existing crustal architecture (pre-transform) and the interplay of syn- and post-transform geodynamic processes. We use a suite of geospatial databases to investigate four transform margins: East Africa (Davie Deformational Zone, DDZ), Equatorial Africa, and the South African and Falkland (Malvinas) margins (Agulhas-Falkland Fracture Zone, AFFZ). The East African margin is the most complex of the four. This is a consequence of Late Jurassic - Early Cretaceous transform motion affecting highly heterogeneous crust, and post-transform deformation that varies along the margin. Equatorial Africa most closely adheres to traditional definitions of “transform margins”, but actually comprises two principal transform systems - the Romanche and St. Pauls, dictated by the pre-transform distribution of mobile belts and West African craton. All four margins are spatially associated with volcanism, and each exhibits narrow uplifts associated with transpression or transtension. But the causal relationship of these features with transform processes differ. Volcanism along the East African margin is pre- and post-transform. Syn-transform volcanism on the AFFZ is spatially limited, with the AFFZ possibly acting as a conduit for magmatism rather than as a causal driver. Transform margins are varied and complex and require an understanding of pre-, syn- and post-transform geodynamics.

Linking Equatorial African precipitation to Kelvin wave processes in the CP4-Africa convection-permitting regional climate simulation

Observational studies have shown the link between Convectively Coupled KelvinWaves (CCKWs) and eastward propagating rainfall anomalies. We explore the mechanisms in which CCKWs modulate the propagation of precipitation from west to east over Equatorial Africa. We examine a multi-year state-of-the-art Africa-wide climate simulation from a convection permitting model (CP4A) along with a parameterised global driving-model simulation (G25) and evaluate both against observations (TRMM) and ERA-Interim (ERA-I), with a focus on precipitation and Kelvin wave activity. We show that the two important related processes through which CCKWs influence the propagation of convection and precipitation from west to east across Equatorial Africa are: 1) low-level westerly wind anomalies that lead to increased low-level convergence, and 2) westerly moisture flux anomalies that amplify the lower-to-mid-tropospheric specific humidity. We identify Kelvin wave activity using zonal wind and geopotential height. Using lagged composite analysis, we show that modelled precipitation over Equatorial Africa can capture the eastward propagating precipitation signal that is associated with CCKWs. Composite analysis on strong (high-amplitude) CCKWs shows that both CP4A and G25 capture the connection between the eastward propagating precipitation anomalies and CCKWs. In comparison to TRMM, however, the precipitation signal is weaker in G25, while CP4A has a more realistic signal. Results show that both CP4A and G25 generally simulate the key horizontal structure of CCKWs, with anomalous low-level westerlies in phase with positive precipitation anomalies. These findings suggest that for operational forecasting, it is important to monitor the day-to-day Kelvin wave activity across Equatorial Africa.

Differences in the genotype frequencies of genes related to blood pressure regulation-a comparative study between South-West Europe and Peri-equatorial Africa

Background: Since the emergence of the genus Homo, hominids have occupied a wide variety of environments, facing different selective pressures. Objectives: The aim this study is to compare genotype frequencies between South-West Europe and Peri-equatorial Africa in genes potentially modulators of blood pressure. Methods: The analyzed sample consisted of 325 individuals from Portugal and 226 individuals from Africa (48 from Mozambique and 178 from São Tomé and Príncipe). The following genetic variants were analyzed: intron 4 VNTR in eNOS, rs1050829 in G6PD, -3.7kb α-thalassemic deletion in HBA, rs1800457 in CYB5R3, Hp 1/2 genotype/phenotype in Hp and intron 16 I/D in ACE. Results: Frequencies of genotypes with the 4a allele in eNOS (p<0.001), the G allele in G6PD (p<0.001), the α-3.7 kb in HBA (p <0.001), the C allele in the CYB5R3 (p<0.001) were higher in Peri-equatorial Africa. The Hp 1.1 genotype of Hp has a higher frequency in Peri-equatorial Africa (p=0.002). ACE shows no significant differences. Conclusion: Results show differences in five genetic variants. Conditions of extreme heat and humidity, characteristic of Peri-equatorial Africa, have been associated with increased sodium loss. This study suggests that selected compensatory mechanisms printed in the genome, are nowadays risk factors for hypertension in Peri-equatorial Africa. Keywords: Blood pressure; genetics; Africa.

Morphological Uniqueness: The Concept and Its Relationship to Indicators of Biological Quality of Human Faces from Equatorial Africa

Facial symmetry, averageness, and the level of sex-typical development of dimorphic traits are traditionally associated with various biological quality indicators and should be, therefore, preferred in mate choice. The aim of this study is to propose a concept of morphological uniqueness and uncover its possible associations to putative phenotypic cues of biological quality. In contrast to typicality expressed by averageness, morphological uniqueness quantifies the degree of possessing characteristics unique to particular groups. I employed a combination of geometric morphometric and Bayesian multiple regression to analyze 300 Cameroonian faces, while an additional 1153 faces from eight distinct populations from across four continents were used as a reference sample of the global population to calculate the morphological uniqueness of Cameroonians. I found that morphological uniqueness is positively associated with a feminine facial shape in women and negatively with morphological masculinity in men. Facial symmetry was positively associated with female faces with greater levels of uniqueness; the result for male faces was inconclusive. The faces of both sexes perceived as more attractive had lower levels of morphological uniqueness. Facial distinctiveness showed no relationship to morphological uniqueness in either sex, which indicates that morphological uniqueness and distinctiveness are two complementary approaches to studying facial typicality. In the conclusion, the evolutionary significance of the proposed concept and its potential applicability is discussed.

Mechanisms of Rainfall Biases in two CORDEX-CORE Regional Climate Models at rainfall peaks over Central Equatorial Africa

Two regional climate models (RCMs) participating in the CORDEX-Coordinated Output for Regional Evaluations (CORDEX-CORE) project feature a dipole-type rainfall bias during March-May (MAM) and September-November (SON) over Central Equatorial Africa (CEA), consisting in positive bias in West Central Equatorial Africa (WCEA) and negative bias in East Central Equatorial Africa (ECEA). One is the REgional MOdel version 2015 (REMO2015), and the other is the fourth version of the Regional Climate Model (RegCM4-v7). RCMs are nested in three Earth System Models (ESMs) from the Coupled Model Intercomparison Project phase 5 (CMIP5), and in the reanalysis ERA-Interim, at ~25 Km spacing-grid resolution. This study highlights misrepresented underlying physical processes associated with these rainfall biases through a process-based evaluation. Both RCMs produce a weaker Congo basin cell, associated with a weaker land-ocean zonal surface pressure gradient. Consequently, less water vapour enters the region, and little amount is transported from WCEA to ECEA, resulting in higher moisture availability in the west than in the east. This leads to an unevenly distributed moisture across the region, favouring a stronger atmospheric instability in WCEA where the moist static energy (MSE) anomalously increases through an enhanced latent static energy (LSE). Moisture arrives at a slower pace in ECEA, associated with the weak cell's strength. The intensity of ascent motions in response to the orographic constraint is weak to destabilise atmospheric stability in the lower layers, necessary for initiating deep convection. Therefore, the convection is shallow in ECEA related to underestimating the MSE due to the reduced LSE.

Educate Kermit Roosevelt Through Sport Hunting and Train Him for Government Missions. Roosevelt Scientific Mission to English Equatorial Africa in 1909

The practice of sport hunting in colonized areas presents a set of knowledge and techniques indispensable to self-control and the domination of territories elsewhere by colonial empires, by their leaders and, more generally, by the political elites of the Northern states. During his scientific mission to English Equatorial Africa in 1909, Theodore Roosevelt responded to a double commission from the Smithsonian Institute and the American Museum in Washington. In this African mission, he brought and trained his youngest son Kermit, aged 20, in an initiatory journey. This article proposes to study this ritual of passage and the practice of sport hunting in the English colonial space as a revelation of the socio-racial hierarchies at work in the territories dominated by the English Empire.

The genetic impact of an Ebola outbreak on a wild gorilla population

Background Numerous Ebola virus outbreaks have occurred in Equatorial Africa over the past decades. Besides human fatalities, gorillas and chimpanzees have also succumbed to the fatal virus. The 2004 outbreak at the Odzala-Kokoua National Park (Republic of Congo) alone caused a severe decline in the resident western lowland gorilla (Gorilla gorilla gorilla) population, with a 95% mortality rate. Here, we explore the immediate genetic impact of the Ebola outbreak in the western lowland gorilla population. Results Associations with survivorship were evaluated by utilizing DNA obtained from fecal samples from 16 gorilla individuals declared missing after the outbreak (non-survivors) and 15 individuals observed before and after the epidemic (survivors). We used a target enrichment approach to capture the sequences of 123 genes previously associated with immunology and Ebola virus resistance and additionally analyzed the gut microbiome which could influence the survival after an infection. Our results indicate no changes in the population genetic diversity before and after the Ebola outbreak, and no significant differences in microbial community composition between survivors and non-survivors. However, and despite the low power for an association analysis, we do detect six nominally significant missense mutations in four genes that might be candidate variants associated with an increased chance of survival. Conclusion This study offers the first insight to the genetics of a wild great ape population before and after an Ebola outbreak using target capture experiments from fecal samples, and presents a list of candidate loci that may have facilitated their survival.