The state of knowledge on the deglaciation of America in 2017

Abstract

This work presents a summary of all contributions included in this Special Issue on the deglaciation of America. It analyses the differences and coincidences between the phases of glacial evolution and their chronology in each of the regions studied, and seeks a possible explanation for asynchronies, according to the opinions of the authors of the contributions. Most of the papers show significant diversity within each region due to local factors and different approaches to their study. Often, local differences are even more important than differences with other regions. In North and Central America glacial evolution appears quite uniform, in line with the evolution of the temperature in the North Atlantic. The differences found between some regions may be due to slight variations in the impact of the temperature of the Atlantic in each region, and to differences in approaching their study. The glacial evolution of the Andes presents a greater diversity, probably due to the existence of arid areas along most of the mountain range, which show a greater sensitivity to the reception of humidity than to temperature in their glacial balance. In general, researchers have detected an attenuation of the influence of the temperature of the North Atlantic towards the south, and of the Antarctic Cold Reversal towards the north.

The deglaciation of the Americas during the Last Glacial Termination

“…These potential problems may not necessarily be solved by collecting and analyzing a larger number of samples from the same glacial landform. If altered boulders or boulders with prior radiation exposure are sampled, the statistic only increases the error (Palacios, 2017). Placing the results of cosmogenic nuclide exposure dating within a suitable geomorphological context is far more important than the statistics themselves.…”

“…The American continents extend 15,000 km from 70ºN to 55ºS and are characterized on their Pacific margins by mountain ranges that are continuous over this distance and, in most cases, now have glaciers or had them during the last glacial period of the Pleistocene. Knowledge of the activity of these glaciers has increased enormously in recent years (Palacios, 2017). This knowledge provides us an opportunity to study how American glaciers behaved during the Last Glacial Termination in the context of the asynchronous climatic setting of the two hemispheres.…”

Genetic variation and phylogeography of the Triatoma dimidiata complex evidence a potential center of origin and recent divergence of haplogroups having differential Trypanosoma cruzi and DTU infections

“…The driest and coolest period in the Neotropical region (both Mexican coasts and the Yucatan peninsula, south through the Tehuantepec Isthmus/Chimalapas rainforest, to CA) was post-LGM, based on a greater proportion of carbon from tropical forests in the region as compared to LGM, or pre-industrial Holocene [64, 66–68]. The Chimalapas rainforest traverses the Tehuantepec Isthmus, an important biogeographic barrier [69, 70], which is the southern border of the Mexican Trans-volcanic belt and Nearctic realm, and it is the northwest limit of the Mesoamerican biodiversity region, and Neotropical realm.…”

Inferring distributional shifts of epidemiologically important North and Central American sandflies from Pleistocene to future scenarios

“…Although glaciation and volcanic activity in the Nearctic (western U.S.A. and northern and intervolcanic high plains of Mexico) produced the most extreme climate conditions primarily in the LGM, the absence of glaciers in the Neotropics (both on the Mexican coasts and south of the Tehuantepec isthmus through Central America) contributed to the driest and coolest period post‐LGM (Vazquez‐Selem & Lachniet, ). The Mexican and Central American Neotropics (including the Yucatán peninsula) were synchronous with that of the northeastern Andes region, having a greater proportion of carbon from tropical forests in the LGM compared with the pre‐industrial Holocene (Haffer, ; Prentice et al ., ; Palacios, ). As temperatures warmed from the LGM to the present, populations isolated in single or multiple refugia often expanded their geographic distributions as new areas became suitable (Waltari et al ., ).…”