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.

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 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 Weeds as Pathogen Hosts and Disease Risk for Crops in the Wake of a Reduced Use of Herbicides: Evidence from Yam (Dioscorea alata) Fields and Colletotrichum Pathogens in the Tropics

2021 ◽  
Vol 7 (4) ◽  
pp. 283
Author(s):  
Pauline Dentika ◽  
Harry Ozier-Lafontaine ◽  
Laurent Penet
Keyword(s):  
Weed Management ◽  
Natural Experiment ◽  
Disease Risk ◽  
Cropping Systems ◽  
Correlation Effect ◽  
Local Scale ◽  
Potential Control ◽  
Weed Host ◽  
Species Characteristics ◽  
The Tropics

The transition toward sustainable agriculture requires rethinking cropping systems in the light of less intensive and chemically reliant practices. Weed management is one of the target practices to evolve cropping systems with decreased impact on the environment. While softened management will lead to increased weeds/crops coexistence, it is of importance to assess the relative benefits and drawbacks of new practices. Among the potential drawbacks of weeds/crops coexistence, disease risk may increase if weeds are hosting pathogens. In this study, we assessed the potential of weeds for hosting pathogenic generalist fungi known to translate into disease in crops. We first describe prevalence in fields after harvest and relate prevalence to species characteristics and communities. Then, we directly test the idea that weeds serve as inoculums sources during cropping with a natural experiment. This study highlights variation in host skill among feral weeds for Colletotrichum species, including potential congeneric sub-specialization on different weeds within communities. Last, prevalence within fields was more correlated to focal crop inoculation rates compared to local weed load, but there was a significant correlation effect with prevalence on weeds in the vicinity of fields, suggesting that weeds are mediating disease levels at the local scale, too. Results pointed to the importance of weed host skill in disease risk yet open the door to the potential control of pathogens via targeted weed management.

scholarly journals Altitudinal distribution, habitat use, and abundance of Grallaria antpittas in the Central Andes of Colombia

1999 ◽  
Vol 9 (3) ◽  
pp. 271-281 ◽  
Author(s):  
Gustavo H. Kattan ◽  
J. William Beltran
Keyword(s):  
Habitat Use ◽  
Habitat Management ◽  
Central Andes ◽  
Local Scale ◽  
Tropical Andes ◽  
Altitudinal Distribution ◽  
River Watershed ◽  
Species Overlap ◽  
Management Plans ◽  
Early Regeneration

SummaryGrallaria antpittas are a group of little known birds from the understorey of humid forests of the tropical Andes, with several species having very narrow distributions. At Ucumari Regional Park, which protects the Otún River watershed in the Central Andes of Colombia, five species occur sympatrically at 2,400 m, including the recently rediscovered G. milleri, of which this is the only known population. We studied the patterns of altitudinal distribution, habitat use and abundance of the five species in the park. We found altitudinal segregation at a local scale, with two species, G. ruficapilla and G. squamigera, found at lower elevations (1,800–2,500 m) and two other species, G. nuchalis and G. rufocinerea, at higher elevations (2,400–3,000); G. milleri was recorded only in the 2,400–2,600 m range. The five species overlap in the range 2,400–2,600 m, where they occur in three habitats: early regeneration, overgrown alder plantations and 30-year-old forest. There were no differences in density among habitats for any species; the five species used the three habitats in proportion to their occurrence in the landscape. Grallaria milleri had the highest overall density (1.3 ind/ha) while G. squamigera had the lowest density (0.2 ind/ha), and the other three species were intermediate. We estimated 106 individuals of G. milleri in an area of 63 ha, and only seven individuals of G. squamigera. The Otún River watershed concentrates an unusual number of Grallaria antpittas, including three endemic species, and the information presented here is fundamental to any future habitat management plans to ensure the persistence of these populations.

Evolutionary conservatism will limit responses to climate change in the tropics

2021 ◽  
Vol 17 (10) ◽  
Author(s):  
Ethan B. Linck ◽  
Benjamin G. Freeman ◽  
C. Daniel Cadena ◽  
Cameron K. Ghalambor
Keyword(s):  
Thermal Tolerance ◽  
Species Turnover ◽  
Tropical Species ◽  
Evolutionary Divergence ◽  
Closely Related Species ◽  
Tropical Mountains ◽  
Low Latitudes ◽  
Parapatric Speciation ◽  
The Tropics

Rapid species turnover in tropical mountains has fascinated biologists for centuries. A popular explanation for this heightened beta diversity is that climatic stability at low latitudes promotes the evolution of narrow thermal tolerance ranges, leading to local adaptation, evolutionary divergence and parapatric speciation along elevational gradients. However, an emerging consensus from research spanning phylogenetics, biogeography and behavioural ecology is that this process rarely, if ever, occurs. Instead, closely related species typically occupy a similar elevational niche, while species with divergent elevational niches tend to be more distantly related. These results suggest populations have responded to past environmental change not by adapting and diverging in place, but instead by shifting their distributions to tightly track climate over time. We argue that tropical species are likely to respond similarly to ongoing and future climate warming, an inference supported by evidence from recent range shifts. In the absence of widespread in situ adaptation to new climate regimes by tropical taxa, conservation planning should prioritize protecting large swaths of habitat to facilitate movement.

Cassia fistula (Indian laburnum).

2021 ◽  
Author(s):  
Marianne Jennifer Datiles ◽  
Pedro Acevedo-Rodríguez
Keyword(s):  
Local Scale ◽  
Cassia Fistula ◽  
Commercial Scale ◽  
Golden Yellow ◽  
The Tropics

Abstract C. fistula is widely planted in the tropics as an ornamental and avenue tree. The timber is hard, strong and durable, and although not available on a commercial scale, is used for a wide variety of purposes on a local scale. The roots, bark, seeds, leaves and pulp from ripe pods are used medicinally. In India, the bark is also widely used in tannin industry. The flowers are golden-yellow, and are used in religious ceremonies in India and Bangladesh. The flowers and buds may be eaten (Krishnamurthy, 1993).

scholarly journals Thermal tolerance patterns across latitude and elevation

2019 ◽  
Vol 374 (1778) ◽  
pp. 20190036 ◽  
Author(s):  
Jennifer Sunday ◽  
Joanne M. Bennett ◽  
Piero Calosi ◽  
Susana Clusella-Trullas ◽  
Sarah Gravel ◽  
...  
Keyword(s):  
Cold Tolerance ◽  
Heat Tolerance ◽  
Thermal Tolerance ◽  
Large Scale ◽  
Global Climate ◽  
Climate Extremes ◽  
Species Traits ◽  
Acclimation Temperature ◽  
Tolerance Limits ◽  
Thermal Limits

Linking variation in species' traits to large-scale environmental gradients can lend insight into the evolutionary processes that have shaped functional diversity and future responses to environmental change. Here, we ask how heat and cold tolerance vary as a function of latitude, elevation and climate extremes, using an extensive global dataset of ectotherm and endotherm thermal tolerance limits, while accounting for methodological variation in acclimation temperature, ramping rate and duration of exposure among studies. We show that previously reported relationships between thermal limits and latitude in ectotherms are robust to variation in methods. Heat tolerance of terrestrial ectotherms declined marginally towards higher latitudes and did not vary with elevation, whereas heat tolerance of freshwater and marine ectotherms declined more steeply with latitude. By contrast, cold tolerance limits declined steeply with latitude in marine, intertidal, freshwater and terrestrial ectotherms, and towards higher elevations on land. In all realms, both upper and lower thermal tolerance limits increased with extreme daily temperature, suggesting that different experienced climate extremes across realms explain the patterns, as predicted under the Climate Extremes Hypothesis . Statistically accounting for methodological variation in acclimation temperature, ramping rate and exposure duration improved model fits, and increased slopes with extreme ambient temperature. Our results suggest that fundamentally different patterns of thermal limits found among the earth's realms may be largely explained by differences in episodic thermal extremes among realms, updating global macrophysiological ‘rules’. This article is part of the theme issue ‘Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen’.

Temperature Tolerance of Bloater (Coregonus hoyi)

1970 ◽  
Vol 27 (11) ◽  
pp. 2047-2052 ◽  
Author(s):  
Thomas A. Edsall ◽  
Donald V. Rottiers ◽  
Edward H. Brown
Keyword(s):  
Young Adult ◽  
High Temperatures ◽  
Thermal Tolerance ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Temperature Tolerance ◽  
Lethal Temperature ◽  
Lethal Temperatures ◽  
Coregonus Artedii ◽  
Coregonus Hoyi

Juvenile and young adult bloaters (Coregonus hoyi) were tested for tolerance to high temperatures. The ultimate upper lethal temperature of juvenile bloaters (26.75 C) appeared to be slightly higher than that of young adult bloaters, but was similar to that of juvenile ciscoes, Coregonus artedii (26.0 C), the only other North American coregonine for which a detailed description of temperature tolerance has been published.Regression equations are given that permit estimation of the thermal tolerance when the lethal temperatures are incompletely known. The estimated thermal tolerance of juvenile bloaters (617 units) was slightly less than that of the brook trout (Salvelinus fontinalis; 625 units), but was higher than that of other Salmonidae.

scholarly journals Global analysis of thermal tolerance and latitude in ectotherms

2010 ◽  
Vol 278 (1713) ◽  
pp. 1823-1830 ◽  
Author(s):  
Jennifer M. Sunday ◽  
Amanda E. Bates ◽  
Nicholas K. Dulvy
Keyword(s):  
Thermal Tolerance ◽  
Large Scale ◽  
Global Analysis ◽  
Marine Species ◽  
Seasonal Temperature ◽  
Geographical Patterns ◽  
Thermal Limits ◽  
Physiological Processes ◽  
Seasonal Temperature Variation ◽  
Do So

A tenet of macroecology is that physiological processes of organisms are linked to large-scale geographical patterns in environmental conditions. Species at higher latitudes experience greater seasonal temperature variation and are consequently predicted to withstand greater temperature extremes. We tested for relationships between breadths of thermal tolerance in ectothermic animals and the latitude of specimen location using all available data, while accounting for habitat, hemisphere, methodological differences and taxonomic affinity. We found that thermal tolerance breadths generally increase with latitude, and do so at a greater rate in the Northern Hemisphere. In terrestrial ectotherms, upper thermal limits vary little while lower thermal limits decrease with latitude. By contrast, marine species display a coherent poleward decrease in both upper and lower thermal limits. Our findings provide comprehensive global support for hypotheses generated from studies at smaller taxonomic subsets and geographical scales. Our results further indicate differences between terrestrial and marine ectotherms in how thermal physiology varies with latitude that may relate to the degree of temperature variability experienced on land and in the ocean.

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