scholarly journals Seed predation increases from the Arctic to the Equator and from high to low elevations

2018 ◽  
Author(s):  
A.L. Hargreaves ◽  
Esteban Suárez ◽  
Klaus Mehltreter ◽  
Isla Myers-Smith ◽  
Sula E. Vanderplank ◽  
...  
Keyword(s):  
Sea Level ◽  
Seed Predation ◽  
Species Interactions ◽  
The Arctic ◽  
Tropical Lowland ◽  
Continuous Forest ◽  
The Pacific ◽  
Animal Interaction ◽  
The Tropics ◽  
High Elevations

AbstractSpecies interactions have long been predicted to increase in intensity towards the tropics and low elevations, due to gradients in climate, productivity, or biodiversity. Despite their importance for understanding global ecological and evolutionary processes, plant-animal interaction gradients are particularly difficult to test systematically across large geographic gradients, and evidence from smaller, disparate studies is inconclusive. By systematically measuring post-dispersal seed predation using 6980 standardized seed depots along 18 mountains in the Pacific cordillera, we found that seed predation increases 18% from the Arctic to Equator and 16% from 4000 masl to sea level. Clines in total predation, likely driven by invertebrates, were consistent across tree-line ecotones and in continuous forest, and were better explained by climate seasonality than by productivity, biodiversity, or latitude. These results suggest that species interactions play predictably greater ecological and evolutionary roles in tropical, lowland, and other less seasonal ecosystems.One Sentence SummaryPost-dispersal seed predation increases from the Arctic to the Equator and from high elevations to sea level.

scholarly journals Seed predation increases from the Arctic to the Equator and from high to low elevations

2019 ◽  
Vol 5 (2) ◽  
pp. eaau4403 ◽  
Author(s):  
A. L. Hargreaves ◽  
Esteban Suárez ◽  
Klaus Mehltreter ◽  
Isla Myers-Smith ◽  
Sula E. Vanderplank ◽  
...  
Keyword(s):  
Sea Level ◽  
Seed Predation ◽  
Species Interactions ◽  
The Arctic ◽  
Evolutionary Processes ◽  
Tropical Lowland ◽  
Continuous Forest ◽  
The Pacific ◽  
Animal Interaction ◽  
The Tropics

Species interactions have long been predicted to increase in intensity toward the tropics and low elevations because of gradients in climate, productivity, or biodiversity. Despite their importance for understanding global ecological and evolutionary processes, plant-animal interaction gradients are particularly difficult to test systematically across large geographic gradients, and evidence from smaller, disparate studies is inconclusive. By systematically measuring postdispersal seed predation using 6995 standardized seed depots along 18 mountains in the Pacific cordillera, we found that seed predation increases by 17% from the Arctic to the Equator and by 17% from 4000 meters above sea level to sea level. Clines in total predation, likely driven by invertebrates, were consistent across treeline ecotones and within continuous forest and were better explained by climate seasonality than by productivity, biodiversity, or latitude. These results suggest that species interactions play predictably greater ecological and evolutionary roles in tropical, lowland, and other less seasonal ecosystems.

scholarly journals Patterns of Sea Ice Retreat in the Transition to a Seasonally Ice-Free Arctic

2016 ◽  
Vol 29 (19) ◽  
pp. 6993-7008 ◽  
Author(s):  
Patricia DeRepentigny ◽  
L. Bruno Tremblay ◽  
Robert Newton ◽  
Stephanie Pfirman
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Large Scale ◽  
System Model ◽  
The Arctic ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The Pacific ◽  
Ice Retreat ◽  
Sea Ice Retreat

Abstract The patterns of sea ice retreat in the Arctic Ocean are investigated using two global climate models (GCMs) that have profound differences in their large-scale mean winter atmospheric circulation and sea ice drift patterns. The Community Earth System Model Large Ensemble (CESM-LE) presents a mean sea level pressure pattern that is in general agreement with observations for the late twentieth century. The Community Climate System Model, version 4 (CCSM4), exhibits a low bias in its mean sea level pressure over the Arctic region with a deeper Icelandic low. A dynamical mechanism is presented in which large-scale mean winter atmospheric circulation has significant effect on the following September sea ice extent anomaly by influencing ice divergence in specific areas. A Lagrangian model is used to backtrack the 80°N line from the approximate time of the melt onset to its prior positions throughout the previous winter and quantify the divergence across the Pacific and Eurasian sectors of the Arctic. It is found that CCSM4 simulates more sea ice divergence in the Beaufort and Chukchi Seas and less divergence in the Eurasian seas when compared to CESM-LE, leading to a Pacific-centric sea ice retreat. On the other hand, CESM-LE shows a more symmetrical retreat between the Pacific, Eurasian, and Atlantic sectors of the Arctic. Given that a positive trend in the Arctic Oscillation (AO) index, associated with low sea level pressure anomalies in the Arctic, is a robust feature of GCMs participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5), these results suggest that the sea ice retreat in the Pacific sector could be amplified during the transition to a seasonal ice cover.

scholarly journals Global pattern of nest predation is disrupted by climate change in shorebirds

Science ◽  
2018 ◽  
Vol 362 (6415) ◽  
pp. 680-683 ◽  
Author(s):  
Vojtěch Kubelka ◽  
Miroslav Šálek ◽  
Pavel Tomkovich ◽  
Zsolt Végvári ◽  
Robert P. Freckleton ◽  
...  
Keyword(s):  
Climate Change ◽  
Nest Predation ◽  
Species Interactions ◽  
Interspecific Interactions ◽  
Global Scale ◽  
Trophic Relationships ◽  
The Arctic ◽  
Global Pattern ◽  
Predator Prey ◽  
The Tropics

Ongoing climate change is thought to disrupt trophic relationships, with consequences for complex interspecific interactions, yet the effects of climate change on species interactions are poorly understood, and such effects have not been documented at a global scale. Using a single database of 38,191 nests from 237 populations, we found that shorebirds have experienced a worldwide increase in nest predation over the past 70 years. Historically, there existed a latitudinal gradient in nest predation, with the highest rates in the tropics; however, this pattern has been recently reversed in the Northern Hemisphere, most notably in the Arctic. This increased nest predation is consistent with climate-induced shifts in predator-prey relationships.

scholarly journals Decadal changes in the leading patterns of sea level pressure in the Arctic and their impacts on the sea ice variability in boreal summer

2019 ◽  
Vol 13 (11) ◽  
pp. 3007-3021
Author(s):  
Nakbin Choi ◽  
Kyu-Myong Kim ◽  
Young-Kwon Lim ◽  
Myong-In Lee
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Boreal Summer ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The Pacific ◽  
Circulation Change ◽  
Arctic Sea

Abstract. Besides its negative trend, the interannual and the interdecadal changes in the Arctic sea ice have also been pronounced in recent decades. The three leading modes in the sea level pressure (SLP) variability in the Arctic (70–90∘ N) – the Arctic Oscillation (AO), the Arctic Dipole (AD), and the third mode (A3) – are analyzed to understand the linkage between sea ice variability and large-scale atmospheric circulation in boreal summer (June–August). This study also compares the decadal changes of the modes between the early (1982–1997) and the recent (1998–2017) periods and their influences on the Arctic sea ice extent (SIE). Only the AD mode shows a significant correlation increase with SIE in summer (JJA) from −0.05 in the early period to 0.57 in the recent period. The AO and the A3 modes show a less significant relationship with SIE for the two periods. The AD is characterized by a dipole pattern of SLP, which modulates the strength of meridional surface winds and the Transpolar Drift Stream (TDS). The major circulation change in the late 1990s is that the direction of the wind has been changed more meridionally over the exit region of the Fram Strait, which causes sea ice drift and discharge through that region. In addition, the response of surface albedo and the net surface heat flux becomes larger and much clearer, suggesting a positive sea-ice–albedo feedback in the sea ice variability associated with the AD. The analysis also reveals that the zonal shift of the centers of SLP anomalies and associated circulation change affects a significant reduction in sea ice concentration over the Pacific sector of the Arctic Ocean. This study further suggests that the Pacific Decadal Oscillation (PDO) phase change could influence the spatial pattern change in the AD.

scholarly journals Decadal Changes in the Leading Patterns of Sea Level Pressure in the Arctic and Their Impacts on the Sea Ice Variability in Boreal Summer

2019 ◽  
Author(s):  
Nakbin Choi ◽  
Kyu-Myong Kim ◽  
Young-Kwon Lim ◽  
Myong-In Lee
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Boreal Summer ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The Pacific ◽  
Circulation Change ◽  
Arctic Sea

Abstract. Besides its negative trend, the interannual and the interdecadal changes in the Arctic sea ice are also pronounced in recent decades. The three leading modes in the sea level pressure (SLP) variability in the Arctic (70°–90 °N) – the Arctic Oscillation (AO), the Arctic Dipole (AD), and the third mode (A3) – are analyzed to understand the linkage between sea ice variability and large-scale atmospheric circulation in boreal summer (June–August). This study also compares the decadal changes of the modes between the early (1982–1997) and the recent (1998–2017) periods and their influences on the Arctic sea ice extent (SIE). Only the AD mode shows a significant correlation increase with SIE from −0.05 in the early period to 0.57 in the recent period. The AO and the A3 modes show a less significant relationship with SIE for the two periods. The AD is characterized by a dipole pattern of SLP, which modulates the strength of meridional surface winds and the transpolar drift stream (TDS). The major circulation change in the late 1990s is that the direction of the wind has been changed more meridionally over the exit region of the Fram Strait, which causes sea ice drift and discharge through that region. The analysis also reveals that the zonal shift of the centers of SLP anomalies and associated circulation change affects a significant reduction in sea ice concentration over the Pacific sector of the Arctic Ocean. This study further suggests that the Pacific Decadal Oscillation (PDO) phase change could influence the spatial pattern change in the AD.

scholarly journals Elevational gradients do not affect thermal tolerance at local scale in populations of livebearing fishes of the genus Limia (Teleostei, Poeciliidae)

2020 ◽  
Author(s):  
Rodet Rodriguez Silva ◽  
Ingo Schlupp
Keyword(s):  
Species Interactions ◽  
Thermal Tolerance ◽  
Distribution Patterns ◽  
Temperature Tolerance ◽  
Local Scale ◽  
Temperature Gradients ◽  
Altitudinal Distribution ◽  
Thermal Limits ◽  
The Tropics ◽  
High Elevations

AbstractOne of the main assumptions of Janzen’s (1976) mountain passes hypothesis is that due the low overlap in temperature regimes between low and high elevations in the tropics, organisms living in high-altitude evolve narrow tolerance for colder temperatures while low-altitude species develop narrow tolerance for warmer temperatures. Some studies have questioned the generality of the assumptions and predictions of this hypothesis suggesting that other factors different to temperature gradients between low and high elevations may explain altitudinal distribution of species in the tropics. We assessed variation in tolerance to extreme temperatures (measured as critical thermal minimum (CTmin) and maximum (CTmax)) and also compared thermal breadth for populations of eight species of livebearing fishes of the genus Limia occurring in three Caribbean islands and that occupy different altitudinal distribution. Our results showed that species analyzed had significant differences in thermal limits and ranges. Generally, species distributed in high and low elevations did not differ in thermal limits and showed a wider range of thermal tolerance. However, species living in mid-elevations had narrower range of temperature tolerance. We found no significant effect of phylogeny on CTmin, CTmax and thermal ranges among species. This study did not provide evidence supporting Janzen’s hypothesis at a local scale since thermal tolerance and altitudinal distribution of Limia species were not related to temperature gradients expected in nature. Phylogeny also did not explain the patterns we observed. We suggest that biotic factors such as species interactions, diet specializations, and others should be taken into account when interpreting current distribution patterns of Limia species.

scholarly journals Mid-upper tropospheric methane retrieval from IASI and its validation

2013 ◽  
Vol 6 (2) ◽  
pp. 2501-2531 ◽  
Author(s):  
X. Xiong ◽  
C. Barnet ◽  
E. S. Maddy ◽  
A. Gambacorta ◽  
T. S. King ◽  
...  
Keyword(s):  
The Arctic ◽  
Aircraft Measurements ◽  
Atmospheric Methane ◽  
Infrared Sensors ◽  
High Northern Latitude ◽  
Observation Network ◽  
The Pacific ◽  
Data Stewardship ◽  
The Tropics ◽  
Cross Track

Abstract. Mid-upper tropospheric atmospheric methane (CH4), as an operational product at NOAA's (National Oceanic and Atmospheric Administration) Comprehensive Large Array-data Stewardship System (CLASS), has been retrieved from the Infrared Atmospheric Sounding Interferometer (IASI) since 2008. This paper provides a description of the retrieval method and the validation using 596 CH4 vertical profiles from aircraft measurements by the HIAPER Pole-to-Pole Observations (HIPPO) program over the Pacific Ocean. The degree of freedom of the CH4 retrieval is mostly less than 1.5, and it decreases under cloudy conditions. The most sensitivity layer is between 100–600 hPa in the tropics, 200–750 hPa in the mid to high latitude. Validation is accomplished using aircraft measurements (convolved by applying the averaging kernels) collocated with all the retrieved profiles within 200 km and in the same day, and the results show that, on average, the largest error of CH4 occurs at 300–500 hPa, and the bias in the trapezoid of 374–477 hPa is −1.74% with residual standard deviation of 1.20%. The retrieval error is relatively larger in the high northern latitude regions and/or under cloudy conditions. The main reasons for this negative bias might be due to the uncertainty in the spectroscopy near methane Q-branch and/or the empirical bias correction, plus cloud-contamination in the cloud-cleared radiances. It is expected for NOAA to generate the CH4 product for 20+ yr using similar algorithm from three similar thermal infrared sensors, i.e. Atmospheric Infrared Sounder (AIRS), IASI and the Cross-track Infrared Sounder (CrIS). Such a unique product will provide a supplementary to current ground-based observation network, particularly in the Arctic, for monitoring the CH4 cycle, its transport and trend associated with climate change.

scholarly journals Elevational gradients do not affect thermal tolerance at local scale in populations of livebearing fishes of the genus Limia (Cyprinodontiformes: Poeciliinae)

2021 ◽  
pp. 46-62
Author(s):  
Rodet Rodriguez-Silva ◽  
Ingo Schlupp
Keyword(s):  
Species Interactions ◽  
Thermal Tolerance ◽  
Temperature Tolerance ◽  
Local Scale ◽  
Temperature Gradients ◽  
Greater Antilles ◽  
Altitudinal Distribution ◽  
Thermal Limits ◽  
The Tropics ◽  
High Elevations

One of the main assumptions of Janzen’s mountain passes hypothesis is that due the low overlap in temperature regimes between low and high elevations in the tropics, organisms living in high-altitude evolve narrow tolerance for colder temperatures while low-altitude species develop narrow tolerance for warmer temperatures. Some studies have questioned the generality of the assumptions and predictions of this hypothesis suggesting that other factors different to temperature gradients between low and high elevations may explain altitudinal distribution of species in the tropics. In this study we test some predictions of the Janzen’s hypothesis at local scales through the analysis of the individual thermal niche breadth in populations of livebearing fishes of the genus Limia and its relationship with their altitudinal distribution in some islands of the Greater Antilles. We assessed variation in tolerance to extreme temperatures (measured as critical thermal minimum (CTmin) and maximum (CTmax) and compared thermal breadth for populations of eight species of Limia occurring in three Caribbean islands and that occupy different altitudinal distribution. Our results showed that species analyzed had significant differences in thermal limits and ranges. Generally, species distributed in high and low elevations did not differ in thermal limits and showed a wider range of thermal tolerance. However, species living in mid-elevations had narrower range of temperature tolerance. We found no significant effect of phylogeny on CTmin, CTmax and thermal ranges among species. This study did not provide evidence supporting Janzen’s hypothesis at a local scale since thermal tolerance and altitudinal distribution of Limia species were not related to temperature gradients expected in nature. Phylogeny also did not explain the patterns we observed. We suggest that biotic factors such as species interactions, diet specializations, and others should be considered when interpreting current distribution patterns of Limia species.

Systematics, Biogeography, and Morphological Character Evolution of the Hemiepiphytic Subfamily Monsteroideae (Araceae)

2019 ◽  
Vol 104 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Alejandro Zuluaga ◽  
Martin Llano ◽  
Ken Cameron
Keyword(s):  
Dna Sequences ◽  
Pacific Islands ◽  
R Package ◽  
Morphological Characters ◽  
Ancestral State ◽  
Seed Shape ◽  
Long Distance ◽  
The Pacific ◽  
And Migration ◽  
The Tropics

The subfamily Monsteroideae (Araceae) is the third richest clade in the family, with ca. 369 described species and ca. 700 estimated. It comprises mostly hemiepiphytic or epiphytic plants restricted to the tropics, with three intercontinental disjunctions. Using a dataset representing all 12 genera in Monsteroideae (126 taxa), and five plastid and two nuclear markers, we studied the systematics and historical biogeography of the group. We found high support for the monophyly of the three major clades (Spathiphylleae sister to Heteropsis Kunth and Rhaphidophora Hassk. clades), and for six of the genera within Monsteroideae. However, we found low rates of variation in the DNA sequences used and a lack of molecular markers suitable for species-level phylogenies in the group. We also performed ancestral state reconstruction of some morphological characters traditionally used for genera delimitation. Only seed shape and size, number of seeds, number of locules, and presence of endosperm showed utility in the classification of genera in Monsteroideae. We estimated ancestral ranges using a dispersal-extinction-cladogenesis model as implemented in the R package BioGeoBEARS and found evidence for a Gondwanan origin of the clade. One tropical disjunction (Monstera Adans. sister to Amydrium Schott–Epipremnum Schott) was found to be the product of a previous Boreotropical distribution. Two other disjunctions are more recent and likely due to long-distance dispersal: Spathiphyllum Schott (with Holochlamys Engl. nested within) represents a dispersal from South America to the Pacific Islands in Southeast Asia, and Rhaphidophora represents a dispersal from Asia to Africa. Future studies based on stronger phylogenetic reconstructions and complete morphological datasets are needed to explore the details of speciation and migration within and among areas in Asia.

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