The Role of Geomorphology in the Quaternary

The advances in understanding of Quaternary geomorphology in the latter half of the 20th Century were closely linked with the improved knowledge of Quaternary climatic fluctuation, principally derived from isotopic evidence from ocean and ice cores. An important goal was finding terrestrial sedimentary records that can be correlated with the globally applicable isotopic sequence. From a geomorphological viewpoint, river terraces are paramount, particularly since they can provide semi-continuous sequences that record palaeoclimate and landscape evolution throughout the Quaternary, as well as the interaction of rivers with glaciation, sea-level change and notable geomorphological events. In coastal areas, shoreline terraces and raised beaches can provide similar sequences. The chapter discusses the progress made in understanding these archives and, in particular, the various mechanisms for dating and correlation, as well as touching upon contributions from other environments, namely slopes and karstic systems, as well as the role of soils in deciphering geomorphological evidence.

Vorarlberg in den Krisenjahren 1816 und 1817: Gründe und Auswirkungen

Vorarlberg in the Crisis Years 1816 and 1817: Reasons and EffectsBetween 1812 and 1817, the so-called "Little Ice Age" in Central Europe reached its climax. During this period, the summers were two to three degrees colder than the 20th century average. In addition to the economic depression caused by the Napoleonic Wars, the eruption of the volcano Tambora in April 1815 further exacerbated the situation. The consequences of the climatic changes affected the whole world and resulted in the "Year Without a Summer" in 1816. The effects of the climatic fluctuation also had an impact on the following year with famines and natural disasters still being a huge problem. Also in Vorarlberg, this resulted in terrible disasters: Flooding, avalanches and crop failures led to years of crisis in Vorarlberg.

Evidence of introgression in endemic frogs from the campo rupestre contradicts the reduced hybridization hypothesis

The campo rupestre ecosystem is considered an old, climatically buffered, infertile landscape. As a consequence, long-term isolation is thought to have played an important role in the diversification of its biota. Here, we tested for hybridization between two endemic leaf frogs from the campo rupestre. We used sequence markers and coalescent models to verify haplotype sharing between the species, to test the existence and direction of gene flow, and to reconstruct the spatiotemporal dynamics of gene flow. Additionally, ecological niche modelling (ENM) was used to assess for potential co-occurrence by overlapping the climatic niche of these species since the middle Pleistocene. We found haplotype sharing and/or lack of differentiation in four nuclear fragments, one of them associated with introgression. The coalescent models support introgressive hybridization unidirectionally from Pithecopus megacephalus to P. ayeaye, occurring ~300 kya. ENM corroborates this scenario, revealing areas of potential environmental niche overlap for the species at about 787 kya. These results contradict the expectation of reduced hybridization, while ENM suggests climatic fluctuation rather than stability for the two species. The reduced hybridization hypothesis needs to be further investigated because our results suggest that it may have unrealistic premises at least for animals.

FISIOGRAFIA DA PAISAGEM E SUAS IMPLICAÇÕES NA GEOMORFOLOGIA DA TERRA INDÍGENA RAPOSA SERRA DO SOL – UIRAMUTÃ/RORAIMA/BRASIL (LANDSCAPE PHYSIOLOGY AND ITS IMPLICATIONS IN THE GEOMORPHOLOGY OF INDIGENOUS LAND RAPOSA SERRA DO SOL - UIRAMUTÃ/RORAIMA/BRAZIL)

RESUMO:A paisagem geomorfológica do estado de Roraima se configura pela presença de relevos cujas altitudes variam entre 80 a 2.800 metros o que constitui um cenário diversificado e exuberante. Nesse sentido, o presente artigo tem como objetivo demonstrar a fisiografia paisagem e sua influênciana geomorfologia da porção norte do munícipio do Uiramutã/Roraima/Brasil, abrangendo a região da Terra Indígena Raposa Serra do Sol. A metodologia utilizada envolveu sobrevoo na região, coleta e análise de solos da região Ingarikó. Os resultados demonstram que a geomorfologia da área é decorrente principalmente devido aos intensos períodos de flutuação climática na região, sendo representada pelo Planalto Sedimentar Roraima que se configura pela presença de diversas formas de relevos, como mesas, morros testemunhos, relevo cuestiforme, morros e colinas ravinadas com a presença de vales suspensos, inúmeros sulcos e ravinas que evoluem para voçorocas, além de facetas trapezoidais e triangulares que refletem a dinâmica do relevo em franco processo de dissecação, que refletem em solos ácidos e pouco teor de fertilidade.Palavras-chave: Paisagem; Flutuação Climática; Dissecação; Roraima. ABSTRACT:The geomorphological landscape of the state of Roraima is formed by the presence of reliefs whose altitudes vary between 80 and 2,800 meters, which constitutes a diversified and exuberant scenery. In this sense, this article aims to demonstrate the landscape physiography and its influence on the geomorphology of the northern part of the municipality of Uiramutã / Roraima / Brazil, covering the region of the Raposa Serra do Sol Indigenous Land. The methodology used involved overflight in the region, collection and soil analysis of the Ingarikó region. The results demonstrate that the geomorphology of the area is mainly due to the intense periods of climatic fluctuation in the region, being represented by the Roraima Sedimentary Plateau, which is formed by the presence of several forms of relief, such as tables, testimonial hills, slopes, hills and hills ravines with the presence of suspended valleys, numerous grooves and ravines that evolve into gullies, as well as trapezoidal and triangular facets that reflect the relief dynamics in a frank dissection process, which reflect in acidic soils and low fertility content.Keywords: Landscape; Climate Fluctuation; Dissection; Roraima

Absence of general rules governing molluscan body-size response to climatic fluctuation during Cenozoic

Body size is a key factor in dictating the fate of interaction between an organism and its surrounding environment. A negative temperature-size relationship (TSR) has been suggested as one of the universal responses to climatic warming. It is also predicted that groups with narrow latitudinal range, tropical affinity and higher body size, would show higher sensitivity to climatic fluctuation. Moreover, because of the difference in thermal sensitivity, it is also expected that the response to climatic fluctuation would be different between epifaunal and infaunal groups. To confirm the generality of these relationship among marine families, we compiled the relationship between body-size and global temperature trends over Cenozoic using a database of marine benthic molluscs of class gastropoda and bivalvia resolved to temporal stages. We evaluated the dependence of climate induced body-size response to the existing size and latitudinal spread via correlating the first-difference correlation coefficient of temperature-size (ρ1st(size-temp)) with maximum size and latitudinal spread of family respectively. Cenozoic record of this highly diverse group does not show any signature of TSR for molluscan class or for any other regional, ecological groups during the past 66My long climatic fluctuation. We did not find any evidence supporting heightened response to climatic fluctuation in groups with limited latitudinal spread or with large body-size. The tropical species did not show significant difference in their body-size response in comparison to temperate species. It also shows lack of any difference in response between ecological groups of molluscs with varying substrate relationship and hence, refutes the predicted variation due to difference in thermal specialization. Although a negative correlation between maximum latitudinal spread and ρ1st(size-temp)is observed for infaunal families, it is not statistically significant. Our results highlight the limited validity of “universal rules” in explaining the climate induced morphological response of marine communities in deep time and underscores the complexity in generalizing the biotic outcome of future climatic fluctuation.