scholarly journals Extreme and variable torpor among high-elevation Andean hummingbird species

2020 ◽  
Vol 16 (9) ◽  
pp. 20200428
Author(s):  
Blair O. Wolf ◽  
Andrew E. McKechnie ◽  
C. Jonathan Schmitt ◽  
Zenon J. Czenze ◽  
Andrew B. Johnson ◽  
...  
Keyword(s):  
Body Temperature ◽  
Air Temperature ◽  
Species Differences ◽  
Phylogenetic Signal ◽  
High Elevation ◽  
Tropical Andes ◽  
Cold Environments ◽  
Fuel Metabolism ◽  
Fat Reserves ◽  
Evolutionarily Conserved

Torpor is thought to be particularly important for small endotherms occupying cold environments and with limited fat reserves to fuel metabolism, yet among birds deep torpor is both rare and variable in extent. We investigated torpor in hummingbirds at approximately 3800 m.a.s.l. in the tropical Andes by monitoring body temperature ( T b ) in 26 individuals of six species held captive overnight and experiencing natural air temperature ( T a ) patterns. All species used pronounced torpor, with one Metallura phoebe reaching a minimum T b of 3.26°C, the lowest yet reported for any bird or non-hibernating mammal. The extent and duration of torpor varied among species, with overnight body mass ( M b ) loss negatively correlated with both minimum T b and bout duration. We found a significant phylogenetic signal for minimum T b and overnight M b loss, consistent with evolutionarily conserved thermoregulatory traits. Our findings suggest deep torpor is routine for high Andean hummingbirds, but evolved species differences affect its depth.

scholarly journals Whole-Genome Resequencing Points to Candidate DNA Loci Affecting Body Temperature under Cold Stress in Siberian Cattle Populations

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 959
Author(s):  
Alexander Igoshin ◽  
Nikolay Yudin ◽  
Ruslan Aitnazarov ◽  
Andrey A. Yurchenko ◽  
Denis M. Larkin
Keyword(s):  
Body Temperature ◽  
Cold Stress ◽  
Candidate Snps ◽  
Whole Genome ◽  
Genome Resequencing ◽  
Functional Annotations ◽  
Cold Environments ◽  
Cold Tolerant ◽  
Cold Sensitive ◽  
Whole Genome Resequencing

Despite the economic importance of creating cold resilient cattle breeds, our knowledge of the genetic basis of adaptation to cold environments in cattle is still scarce compared to information on other economically important traits. Herein, using whole-genome resequencing of animals showing contrasting phenotypes on temperature maintenance under acute cold stress combined with the existing SNP (single nucleotide polymorphism) functional annotations, we report chromosomal regions and candidate SNPs controlling body temperature in the Siberian cattle populations. The SNP ranking procedure based on regional FST calculations, functional annotations, and the allele frequency difference between cold-tolerant and cold-sensitive groups of animals pointed to multiple candidate genes. Among these, GRIA4, COX17, MAATS1, UPK1B, IFNGR1, DDX23, PPT1, THBS1, CCL5, ATF1, PLA1A, PRKAG1, and NR1I2 were previously related to thermal adaptations in cattle. Other genes, for example KMT2D and SNRPA1, are known to be related to thermogenesis in mice and cold adaptation in common carp, respectively. This work could be useful for cattle breeding strategies in countries with harsh climates, including the Russian Federation.

Environmental and spatial filters of zooplankton metacommunities in shallow pools in high-elevation peatlands in the tropical Andes

2018 ◽  
Vol 63 (5) ◽  
pp. 432-442 ◽  
Author(s):  
Estefania Quenta Herrera ◽  
Dean Jacobsen ◽  
Jérôme Casas ◽  
Olivier Dangles
Keyword(s):  
High Elevation ◽  
Tropical Andes ◽  
Spatial Filters

Temperature and vegetation complexity structure mixed-species flocks along a gradient of elevation in the tropical Andes

The Auk ◽  
2021 ◽  
Author(s):  
Flavia A Montaño-Centellas ◽  
Harrison H Jones
Keyword(s):  
Species Richness ◽  
Abiotic Stress ◽  
Environmental Gradients ◽  
Bird Community ◽  
Taxonomic Diversity ◽  
High Elevation ◽  
Tropical Andes ◽  
Mixed Species ◽  
Mixed Species Flocks ◽  
Species Flocks

Abstract Mixed-species flocks constitute community modules that can help test mechanisms driving changes to community composition across environmental gradients. Here, we examined elevational patterns of flock diversity (species richness, taxonomic diversity, species, and guild composition) and asked if these patterns were reflections of the full bird community at a given elevation (open-membership hypothesis), or if they were instead structured by environmental variables. We surveyed both the overall avian community and mixed-species flocks across an undisturbed elevational gradient (~1,350–3,550 m) in the Bolivian Andes. We then tested for the role of temperature (a surrogate for abiotic stress), resource diversity (arthropods, fruits), and foraging niche diversity (vegetation vertical complexity) in structuring these patterns. Patterns for the overall and flocking communities were similar, supporting our open-membership hypothesis that Andean flocks represent dynamic, unstructured aggregations. Membership openness and the resulting flock composition, however, also varied with elevation in response to temperature and vegetation complexity. We found a mid-elevation peak in flock species richness, size, and Shannon’s diversity at ~2,300 m. The transition of flocking behavior toward a more open-membership system at this elevation may explain a similar peak in the proportion of insectivores joining flocks. At high elevations, increasing abiotic stress and decreasing fruit diversity led more generalist, gregarious tanagers (Thraupidae) to join flocks, resulting in larger yet more even flocks alongside a loss of vegetation structure. At lower elevations, flock species richness increased with greater vegetation complexity, but a greater diversity of foraging niches resulted in flocks that were more segregated into separate canopy and understory sub-types. This segregation likely results from increased costs of interspecific competition and activity matching (i.e., constraints on movement and foraging rate) for insectivores. Mid-elevation flocks (~2,300 m) seemed, therefore, to benefit from both the open-membership composition of high-elevation flocks and the high vegetation complexity of mid- and low-elevation forests.

Fluvial sediment fluxes response to modern climate change and human activities in the Tibetan Plateau and its margins

2021 ◽  
Author(s):  
Dongfeng Li ◽  
Xixi Lu ◽  
Ting Zhang
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Human Activities ◽  
Sediment Flux ◽  
The Tibetan Plateau ◽  
Fluvial Sediment ◽  
Sediment Fluxes ◽  
Cold Environments

<p>Sediment flux in cold environments is a crucial proxy to link glacial, periglacial, and fluvial systems and highly relevant to hydropower operation, water quality, and the riverine carbon cycle. However, the long-term impacts of climate change and multiple human activities on sediment flux changes in cold environments remain insufficiently investigated due to the lack of monitoring and the complexity of the sediment cascade. Here we examine the multi-decadal changes in the in-situ observed fluvial sediment fluxes from two types of basins, namely, pristine basins and disturbed basins, in the Tibetan Plateau and its margins. The results show that the fluvial sediment fluxes in the pristine Tuotuohe headwater have substantially increased over the past three decades (i.e., a net increase of 135% from 1985–1997 to 1998–2017) due to the warming and wetting climate. We also quantify the relative impacts of air temperature and precipitation on the increases in the sediment fluxes with a novel attribution approach and finds that climate warming and intensified glacier-snow-permafrost melting is the primary cause of the increased sediment fluxes in the pristine cold environment (Tuotuohe headwater), with precipitation increase and its associated pluvial processes being the secondary driver. By contrast, the sediment fluxes in the downstream disturbed Jinsha River (southeastern margin of the Tibetan Plateau) exhibit a net increase of 42% from 1966-1984 to 1985-2010 mainly due to human activities such as deforestation and mineral extraction (contribution of 82%) and secondly because of climate change (contribution of 18%). Then the sediment fluxes dropped by 76% during the period of 2011-2015 because of the operations of six cascade reservoirs since 2010. In an expected warming and wetting climate for the region, we predict that the sediment fluxes in the pristine headwaters of the Tibetan Plateau will continue to increase throughout the 21st century, but the rising sediment fluxes from the Tibetan Plateau would be mostly trapped in its marginal reservoirs.</p><p>Overall, this work has provided the sedimentary evidence of modern climate change through robust observational sediment flux data over multiple decades. It demonstrates that sediment fluxes in pristine cold environments are more sensitive to air temperature and thermal-driven geomorphic processes than to precipitation and pluvial-driven processes. It also provides a guide to assess the relative impacts of human activities and climate change on fluvial sediment flux changes and has significant implications for water resources stakeholders to better design and manage the hydropower dams in a changing climate. Such findings may also have implications for other cold environments such as the Arctic, Antarctic, and other high mountainous basins.</p><p>Furthermore, this research is under the project of "Water and Sediment Fluxes Response to Climate Change in the Headwater Rivers of Asian Highlands" (supported by the IPCC and the Cuomo Foundation) and the project of "Sediment Load Responses to Climate Change in High Mountain Asia" (supported by the Ministry of Education of Singapore). Part of the results are also published in Li et al., 2018 Geomorphology, Li et al., 2020 Geophysical Research Letters, and Li et al., 2021 Water Resources Research.</p>

Palaeoglaciation in the low latitude, low elevation tropical Andes, northern Peru

2021 ◽  
Author(s):  
Ethan Lee ◽  
Neil Ross ◽  
Andrew Henderson ◽  
Andrew Russell ◽  
Stewart Jamieson ◽  
...  
Keyword(s):  
High Elevation ◽  
Tropical Andes ◽  
Low Latitude ◽  
Climate History ◽  
Ongoing Research ◽  
Important Region ◽  
Ongoing Work ◽  
Geomorphological Map ◽  
Northern Peru ◽  
Data Gap

<p>Palaeo-glaciological studies of former ice thickness and extent within the tropical Andes have tended to focus on locations where glaciers are currently present, or in high elevation locations where evidence exists of recently deglaciated cirques. Few studies have focussed on low elevation regions due to the presumption that glaciers could not have existed at such low altitudes within the tropics. A latitudinal ‘data gap’ exists between Ecuador and more central and southern Peru where evidence for former glaciation is abundant. To fill this gap we present rare evidence of past glaciation from the Las Huaringas region, northern Peru, located in a relatively low elevation massif (<3900 m).</p><p>Within Las Huaringas a large valley glacier existed, extending N-S ~12 km down valley to ~2900 m in elevation while glacial cirques existed exhibiting an E-W orientation on the western facing hillslope of the massif with pronounced moraine complexes and bedrock erosion. We used high-resolution remotely sensed imagery, a 30 m ALOS DEM, and preliminary field observations to identify and map an abundance of geomorphic evidence of glaciation. These include moraines at different stages of preservation and predominance, eroded bedrock surfaces, cirque landforms and overdeepened valleys to develop the first glacial geomorphological map of the region. We performed morphometric analysis (e.g. width, length, altitude, azimuth) of the mapped glacial landforms and cirques along with hypsometric analysis of the main valley of Laguna Shimbe, yielding a hypsometric maxima of 3250 m. Using the geomorphological map, we determine the former extent and thickness of palaeoglaciers in the area and use delineated glacial outlines of their furthest extent to reconstruct Equilibrium Line Altitudes (ELAs) of these ice masses using a combination of ELA estimation techniques.</p><p>Ongoing research aims to determine whether the palaeoglacial evidence is consistent with formation by valley glaciers or an icecap and whether the timing of the local Last Glacial Maximum (LGM) was synchronous with the global timing. A set of hypotheses for the timing and drivers of the reconstructed extent of former glaciers in the area will be presented. Our analysis confirms the presence of former glaciers in a low elevation and low latitude region of the tropical Andes. Our ongoing work aims to unveil the timing of the glacial events and the drivers of the glacial and climate history seen within this important region.</p>

scholarly journals Centennial-scale precipitation anomalies in the southern Altiplano (18° S) suggest an extratropical driver for the South American summer monsoon during the late Holocene

2019 ◽  
Vol 15 (5) ◽  
pp. 1845-1859 ◽  
Author(s):  
Ignacio A. Jara ◽  
Antonio Maldonado ◽  
Leticia González ◽  
Armand Hernández ◽  
Alberto Sáez ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Large Scale ◽  
Southern Oscillation ◽  
Atlantic Coast ◽  
Austral Summer ◽  
High Elevation ◽  
South American ◽  
Tropical Andes ◽  
The South ◽  
Precipitation Anomalies

Abstract. Modern precipitation anomalies in the Altiplano, South America, are closely linked to the strength of the South American summer monsoon (SASM), which is influenced by large-scale climate features sourced in the tropics such as the Intertropical Convergence Zone (ITCZ) and El Niño–Southern Oscillation (ENSO). However, the timing, direction, and spatial extent of precipitation changes prior to the instrumental period are still largely unknown, preventing a better understanding of the long-term drivers of the SASM and their effects over the Altiplano. Here we present a detailed pollen reconstruction from a sedimentary sequence covering the period between 4500 and 1000 cal yr BP in Lago Chungará (18∘ S; 4570 m a.s.l.), a high-elevation lake on the southwestern margin of the Altiplano where precipitation is delivered almost exclusively during the mature phase of the SASM over the austral summer. We distinguish three well-defined centennial-scale anomalies, with dry conditions between 4100–3300 and 1600–1000 cal yr BP and a conspicuous humid interval between 2400 and 1600 cal yr BP, which resulted from the weakening and strengthening of the SASM, respectively. Comparisons with other climate reconstructions from the Altiplano, the Atacama Desert, the tropical Andes, and the southwestern Atlantic coast reveal that – unlike modern climatological controls – past precipitation anomalies at Lago Chungará were largely decoupled from north–south shifts in the ITCZ and ENSO. A regionally coherent pattern of centennial-scale SASM variations and a significant latitudinal gradient in precipitation responses suggest the contribution of an extratropical moisture source for the SASM, with significant effects on precipitation variability in the southern Altiplano.

scholarly journals Soil and Air Temperature Calibrations Using Branched GDGTs for the Tropical Andes of Colombia: Toward a Pan‐Tropical Calibration

2020 ◽  
Vol 21 (8) ◽  
Author(s):  
Lina C. Pérez‐Angel ◽  
Julio Sepúlveda ◽  
Peter Molnar ◽  
Camilo Montes ◽  
Balaji Rajagopalan ◽  
...  
Keyword(s):  
Air Temperature ◽  
Tropical Andes

Thermal influence of sunshine and clothing on men walking in humid heat

1962 ◽  
Vol 17 (2) ◽  
pp. 311-316 ◽  
Author(s):  
F. N. Craig ◽  
E. G. Cummings
Keyword(s):  
Body Temperature ◽  
Temperature Gradient ◽  
Air Temperature ◽  
Indoor Air ◽  
Physiological Strain ◽  
Mean Body Temperature ◽  
Clothing Insulation ◽  
Air Temperatures ◽  
Rate Of Increase ◽  
Thermal Influence

For two men walking on a treadmill and wearing two layers of permeable clothing, the same physiological strain measured by the rate of increase in mean body temperature could be produced a) next to a building outdoors in the sunshine with an average air temperature of 85 F and humidity of 20 mm Hg and b) indoors with the same humidity and an air temperature 10 F higher. Under these conditions, the underwear was mainly wet with sweat and the outer layer was mainly dry. In comparable indoor tests on a third subject, the temperature of the underwear approached equilibrium 1 or 2 F lower than the temperature of the skin at air temperatures of 85 and 115 F. The error in calculating clothing insulation introduced by assuming the clothing to be dry is determined by the size and direction of the temperature gradient between skin and air. Adding 10 F to the indoor air temperature does not duplicate all the effects of sunshine. Submitted on September 15, 1961

scholarly journals The Regulation of Body Temperature in Extremes of Dry Heat

1912 ◽  
Vol 12 (4) ◽  
pp. 479-488 ◽  
Author(s):  
E. H. Hunt
Keyword(s):  
Body Temperature ◽  
Air Temperature ◽  
The Body ◽  
Strong Argument ◽  
Dry Heat ◽  
Healthy Man ◽  
Large Reserve

(1) Comfort and health can readily be maintained in dry heat where for long periods the air temperature is above that of the body.(2) The amount of water absolutely required, and actually consumed, is very large; and this is accounted for by the necessity for neutralising, in some circumstances, the whole heat of metabolism (requiring up to 6,000 c.c.) and in addition a variable but sometimes very large amount of heat added to the body by radiation and conduction.(3) A healthy man carries in his body a large reserve of water, this reserve being mainly stored in muscle and being so readily available that the percentage of water in the blood is not appreciably diminished even when several litres of water have been lost by sweating. If, however, it be extensively drawn on, replacement seems to occupy many hours, and this delay is an important factor, forming a strong argument against any undue or needless use of the stored water owing to restriction of drinking.

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