Integrated reconstruction of Holocene millennial-scale environmental changes in Tierra del Fuego, southernmost South America

2014 ◽  
Vol 399 ◽  
pp. 294-309 ◽  
Author(s):  
Nicolás Waldmann ◽  
Ana Maria Borromei ◽  
Cristina Recasens ◽  
Daniela Olivera ◽  
Marcelo A. Martínez ◽  
...  
Keyword(s):  
South America ◽  
Environmental Changes ◽  
Tierra Del Fuego ◽  
Millennial Scale

Future Environments of South America

2007 ◽  
Author(s):  
Thomas T. Veblen ◽  
Kenneth R. Young
Keyword(s):  
South America ◽  
Environmental Change ◽  
Environmental Changes ◽  
Human Impacts ◽  
Southern Oscillation ◽  
Physical Geography ◽  
Tierra Del Fuego ◽  
South American ◽  
Policy Options ◽  
Natural Processes

An important goal of this book has been to provide a comprehensive understanding of the physical geography and landscape origins of South America as important background to assessing the probabilities and consequences of future environmental changes. Such background is essential to informed discussions of environmental management and the development of policy options designed to prepare local, national, and international societies for future changes. A unifying theme of this book has been the elucidation of how natural processes and human activities have interacted in the distant and recent past to create the modern landscapes of the continent. This retrospective appreciation of how the current landscapes have been shaped by nature and humans will guide our discussion of possible future trajectories of South American environments. There is abundant evidence from all regions of South America, from Tierra del Fuego to the Isthmus of Panama, that environmental change, not stasis, has been the norm. Given that fact, the history, timing, and recurrence intervals of this dynamism are all crucial pieces of information. The antiquity and widespread distribution of changes associated with the indigenous population are now well established. Rates and intensities of changes related to indigenous activities varied widely, but even in regions formerly believed to have experienced little or no pre-European impacts we now recognize the effects of early humans on features such as soils and vegetation. Colonization by Europeans mainly during the sixteenth century modified or in some cases replaced indigenous land-use practices and initiated changes that have continued to the present. Complementing these broad historical treatments of human impacts, other chapters have examined in detail the environmental impacts of agriculture (chapter 18) and urbanism (chapter 20), and the disruptions associated with El Niño–Southern Oscillation events. The goal of this final synthesis is to identify the major drivers of change and to discuss briefly their likely impacts on South American environments and resources in the near and medium-term future. Our intent is not to make or defend predictions, but rather to identify broad causes and specific drivers of environmental change to inform discussions of policy options for mitigating undesirable changes and to facilitate potential societal adaptations to them.

Testing ecological and environmental changes during the last 6000 years: a multiproxy approach based on the bivalve Tawera gayi from southern South America

2011 ◽  
Vol 91 (7) ◽  
pp. 1413-1427 ◽  
Author(s):  
Sandra Gordillo ◽  
Julieta Martinelli ◽  
Javiera Cárdenas ◽  
M. Sol Bayer
Keyword(s):  
Stable Isotopes ◽  
South America ◽  
Late Holocene ◽  
Environmental Changes ◽  
Growth Dynamics ◽  
Tierra Del Fuego ◽  
Physical Factors ◽  
Geological Time ◽  
Southern South America ◽  
Ecological Variability

This paper evaluates if the bivalve Tawera gayi from southern South America represents an opportunity to test ecological variability and environmental changes during the last 6000 years in southern South America. For this purpose, we analyse both modern and fossil (mid-to-late Holocene) T. gayi shells from Tierra del Fuego using different techniques, including taphonomy, stable isotopes, cathodoluminiscence (CL) and linear morphometrics. Taphonomic analysis shows that differences between modern and fossil shells appear best related to local variations of physical factors such as current speed, wave action and freshwater input along the non-uniform Beagle Channel coast. However, slight changes of hydraulic energy regimes throughout the Holocene cannot be ruled out. The analysis of stable isotopes on T. gayi shells indicates a mixing of oceanic waters with freshwater from precipitation, river runoff and glacier meltwater during the mid-to-late Holocene. The high depletion of δ18O at ~4400 years before present would be associated with a period of warmer temperatures, the so-called Hypsithermal. Under CL modern and fossil T. gayi shells show a well defined pattern related to the growth dynamics of the shell, which can lead to a better understanding of its biology, adding details to further palaeoenvironmental analysis. Finally, conventional metrics shows that fossil T. gayi shells are smaller and shorter than modern shells. These differences could be related to Holocene environmental changes, but here are best explained on the basis of a predator–prey relationship. This study shows that T. gayi may be a good candidate for looking at evidences of environmental changes in southern South America, and multi-proxy data are necessary to better understand the driving mechanisms of ecological variability and changes over short geological time intervals of few thousands of years.

Species distribution modeling reveals the ecological niche of extinct megafauna from South America

2021 ◽  
pp. 1-8
Author(s):  
Thaísa Araújo ◽  
Helena Machado ◽  
Dimila Mothé ◽  
Leonardo dos Santos Avilla
Keyword(s):  
South America ◽  
Species Distribution ◽  
Environmental Changes ◽  
Species Distribution Modeling ◽  
Human Action ◽  
Northeastern Brazil ◽  
Climate Conditions ◽  
Middle Holocene ◽  
Distribution Modeling ◽  
The Impact

Abstract Climatic and environmental changes, as well as human action, have been cited as potential causes for the extinction of megafauna in South America at the end of the Pleistocene. Among megamammals lineages with Holarctic origin, only horses and proboscideans went extinct in South America during this period. This study aims to understand how the spatial extent of habitats suitable for Equus neogeus and Notiomastodon platensis changed between the last glacial maximum (LGM) and the middle Holocene in order to determine the impact that climatic and environmental changes had on these taxa. We used species distribution modeling to estimate their potential extent on the continent and found that both species occupied arid and semiarid open lands during the LGM, mainly in the Pampean region of Argentina, southern and northeastern Brazil, and parts of the Andes. However, when climate conditions changed from dry and cold during the LGM to humid and warm during the middle Holocene, the areas suitable for these taxa were reduced dramatically. These results support the hypothesis that climatic changes were a driving cause of extinction of these megamammals in South America, although we cannot rule out the impact of human actions or other potential causes for their extinction.

Salicornia cuscoensis (Amaranthaceae/Chenopodiaceae), a new species from Peru (South America)

Phytotaxa ◽  
2017 ◽  
Vol 319 (3) ◽  
pp. 254 ◽  
Author(s):  
M. ÁNGELES ALONSO ◽  
MANUEL B. CRESPO ◽  
HELMUT FREITAG
Keyword(s):  
New Species ◽  
South America ◽  
Morphological Characters ◽  
Tierra Del Fuego ◽  
South American ◽  
Habitat Distribution ◽  
Closely Related Species ◽  
Molecular Analyses ◽  
Southern Patagonia ◽  
A New Species

The name Salicornia cuscoensis given to a plant from high Andean saltmarshes near Cusco [Cuzco] and Ayacucho, Peru (South America) is validated by a diagnosis and description. The main morphological characters that separate S. cuscoensis from other closely related species are creeping habit, delicate branches, inflorescence of short and thin spikes, and seed indumentum. The new species clearly differs from other perennial Salicornia taxa growing in high Andean saltmarshes such as S. pulvinata and S. andina. The former forms small compact cushions producing very short, few-flowered inflorescences. The latter shows woody stems and forms larger rounded carpets. Morphologically, S. cuscoensis is also similar to S. magellanica, a species growing along the seashore in southern Patagonia and Tierra del Fuego, but the latter has shorter and wider inflorescences and larger seeds with a different type and arrangement of indumentum. Molecular analyses also supported the separation of S. cuscoensis. Data on habitat, distribution and phylogenetic relationships are presented for the new species and its relatives, and an identification key is given for the South American taxa of the genus Salicornia.

scholarly journals Quality assessment of chronologies in Latin American pollen records: a contribution to centennial to millennial scale studies of environmental change

2015 ◽  
Vol 11 (2) ◽  
pp. 1219-1262 ◽  
Author(s):  
S. G. A. Flantua ◽  
H. Hooghiemstra ◽  
M. Blaauw
Keyword(s):  
South America ◽  
Quality Assessment ◽  
Latin American ◽  
Time Windows ◽  
Uncertainty Assessment ◽  
Last Deglaciation ◽  
Age Model ◽  
Millennial Time Scale ◽  
Pollen Records ◽  
Millennial Scale

Abstract. The newly updated inventory of the Latin American Pollen Database (LAPD) offers an important overview of data available for multi-proxy and multi-site purposes. However, heterogeneous paleoecological databases are not suitable to be integrated without an uncertainty assessment of existing chronologies. Therefore, we collected all chronological control points and age model metadata from the LAPD literature to create a complementary chronological database of 5116 dates from 1097 pollen records. We start with an overview on chronological dating and reporting in Central and South America. Specific problems and recommendations for chronology reporting are discussed. Subsequently, we implement a temporal quality assessment of pollen records from northwest South-America to support research on climate forcers and responses at a centennial-millennial time-scale. New chronologies are generated for 233 pollen records based on updated calibration curves. Different time windows are discussed on sample resolution and temporal uncertainty. Approximately one in four pollen diagrams depicts < 500 years resolution data at the Younger Dryas/Holocene transition. Overall, our analyses suggest that the temporal resolution of multi-site syntheses of late Pleistocene fossil pollen records in the northwest South-America is ca. 240 years, a resolution which allows analysis of ecological responses to centennial-millennial-scale climate change during the last deglaciation.

scholarly journals First record of tuberculosis lesions in zooarchaeological samples of otariid pinnipeds. New aspects of the pre-european origin of human tuberculosis in South America and dissemination mechanisms of Mycobacterium pinnipedii in the Southern Hemisphere

2020 ◽  
Vol 24 (3) ◽  
pp. 227-253
Author(s):  
Ricardo Bastida ◽  
Viviana Quse ◽  
María Paz Martinoli ◽  
Atilio Francisco Zangrando
Keyword(s):  
South America ◽  
Southern Hemisphere ◽  
First Record ◽  
Tierra Del Fuego ◽  
Bone Lesions ◽  
Tuberculosis Complex ◽  
European Origin ◽  
Wild Mammals ◽  
Pinniped Species ◽  
New Hypothesis

In 2003 Mycobacterium pinnipedii was described as responsible for producing tuberculosis (TB) in living otariid pinnipeds from Argentina and Australia. It is the only member of marine origin within the Mycobacterium tuberculosis Complex (MTBC), which also affects other domestic and wild mammals, and humans. Based on several pre-Columbian records of human tuberculosis in South America, in 2010-2011 a new hypothesis about the origin of this zoonosis through otariid pinnipeds arose. In 2014, this hypothesis was confirmed based on the study of ancient DNA from three mummies (700-1,000 years BP) of the Chiribaya culture (Peru). Since there were no records of TB bone lesions in zooarchaeological samples of otariid pinnipeds from South America and the rest of the world, our study aimed at examining zooarchaeological samples of pinnipeds from coastal sites of the Beagle Channel (Tierra del Fuego, Argentina), being the oldest Túnel I (6,400-4,300 years BP). A total of 4,138 vertebrae were analyzed, of which 0.46 % showed lesions compatible with TB. In addition, we propose a new hypothesis on possible mechanisms of Mycobacterium pinnipedii dissemination that would explain the transmission routes to the different otariid pinniped species of the Southern Hemisphere. Mycobacterium pinnipedii is one of the most aggressive mycobacteria of the MTBC and of high risk for humans.

Cyttaria darwinii. [Descriptions of Fungi and Bacteria].

2004 ◽  
Author(s):  
I. J. Gamundí
Keyword(s):  
South America ◽  
Geographical Distribution ◽  
Wood Decay ◽  
Golf Ball ◽  
Tierra Del Fuego ◽  
Santa Cruz ◽  
Obligate Parasite ◽  
Rio Negro ◽  
Nothofagus Antarctica ◽  
Highly Evolved

Abstract A description is provided for Cyttaria darwinii. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: A highly evolved and highly specific obligate parasite causing often spectacular cankers only on branches of Nothofagus species. Fruitbodies only appear on the cankers; this fungus does not cause wood decay. HOSTS: Nothofagus antarctica, N. betuloides, N. dombeyi, N. pumilio, Nothofagus sp. (Fagaceae); more than 70% of all records are from N. antarctica and N. pumilio. GEOGRAPHICAL DISTRIBUTION: SOUTH AMERICA: Argentina (Chubut, Neuquén, Río Negro, Santa Cruz, Tierra del Fuego); Chile (Aisén, Los Lagos, Magallanes y Antártica Chilena, Bío-Bío, Maule). Highest recorded altitude: 1700 m. TRANSMISSION: Not known, but presumably infection is by wind-dispersed ascospores. The reasons postulated by INGOLD (1988) for evolution of the golf ball shape of fruitbodies of Cyttaria espinosae [IMI Descriptions No. 1593] are doubtless also valid for this species.

Cyttaria hariotii. [Descriptions of Fungi and Bacteria].

2004 ◽  
Author(s):  
I. J. Gamundí
Keyword(s):  
South America ◽  
Geographical Distribution ◽  
Wood Decay ◽  
Golf Ball ◽  
Tierra Del Fuego ◽  
Obligate Parasite ◽  
Rio Negro ◽  
Nothofagus Antarctica ◽  
Highly Evolved

Abstract A description is provided for Cyttaria hariotii. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: A highly evolved and highly specific obligate parasite causing often spectacular cankers only on branches of Nothofagus species. Fruitbodies only appear on the cankers; this fungus does not cause wood decay. HOSTS: Nothofagus antarctica, N. betuloides, N. dombeyi, N. nitida, N. pumilio, Nothofagus sp. (Fagaceae) [old fallen ascomata have also been recorded on soil, being blackish]. GEOGRAPHICAL DISTRIBUTION: SOUTH AMERICA: Argentina (Chubut, Neuquén, Río Negro, Tierra del Fuego); Chile (Aisén, La Araucanía, Los Lagos, Magallanes y Antártica Chilena, Bío-Bío, Maule). Highest recorded altitude: 1000 m. TRANSMISSION: Not known, but presumably infection is by wind-dispersed ascospores. The reasons postulated by INGOLD (1988) for evolution of the golf ball shape of fruitbodies of Cyttaria espinosae [IMI Descriptions No. 1593] are doubtless also valid for this species.

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