Some Concepts of Bioecology

Shelford, V. E.

doi:10.2307/1928991

Cited by 201 publications

(124 citation statements)

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“…In accordance with the prediction developed above, oxygen uptake and distribution by ventilation and circulation are most likely those processes of a high organisational complexity which set the limits of thermal tolerance. Shelford (1931) defined the law of tolerance, which was used and extended by Schwerdtfeger (1977) to describe the changing performance of organisms within optimum, pejus and pessimum phases of the tolerance range with respect to environmental factors. Frederich and Pörtner (2000) applied the respective terminology to the profile of haemolymph PO 2 obtained in M. squinado (Fig.…”

Section: Capacity-limited Ventilation and Circulationmentioning

confidence: 99%

Climate change and temperature-dependent biogeography: oxygen limitation of thermal tolerance in animals

Pörtner

2001

Naturwissenschaften

949

232

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Recent years have shown a rise in mean global temperatures and a shift in the geographical distribution of ectothermic animals. For a cause and effect analysis the present paper discusses those physiological processes limiting thermal tolerance. The lower heat tolerance in metazoa compared with unicellular eukaryotes and bacteria suggests that a complex systemic rather than molecular process is limiting in metazoa. Whole-animal aerobic scope appears as the first process limited at low and high temperatures, linked to the progressively insufficient capacity of circulation and ventilation. Oxygen levels in body fluids may decrease, reflecting excessive oxygen demand at high temperatures or insufficient aerobic capacity of mitochondria at low temperatures. Aerobic scope falls at temperatures beyond the thermal optimum and vanishes at low or high critical temperatures when transition to an anaerobic mitochondrial metabolism occurs. The adjustment of mitochondrial densities on top of parallel molecular or membrane adjustments appears crucial for maintaining aerobic scope and for shifting thermal tolerance. In conclusion, the capacity of oxygen delivery matches full aerobic scope only within the thermal optimum. At temperatures outside this range, only time-limited survival is supported by residual aerobic scope, then anaerobic metabolism and finally molecular protection by heat shock proteins and antioxidative defence. In a cause and effect hierarchy, the progressive increase in oxygen limitation at extreme temperatures may even enhance oxidative and denaturation stress. As a corollary, capacity limitations at a complex level of organisation, the oxygen delivery system, define thermal tolerance limits before molecular functions become disturbed.

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Section: Capacity-limited Ventilation and Circulationmentioning

confidence: 99%

Climate change and temperature-dependent biogeography: oxygen limitation of thermal tolerance in animals

Pörtner

2001

Naturwissenschaften

949

232

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“…Terminology was applied by adopting the one used in Shelford's law of tolerance (Shelford, 1931). In the spider crab Maja squinado, early limits of thermal tolerance during both heating and cooling were indicated by a set of low and high peius temperatures (T p ), which denote the beginning of insufficient oxygen supply to an organism, or in other words, the onset of mildly hypoxic conditions associated with a progressive loss in aerobic scope.…”

Section: Introduction: a Role For Hypoxia In Thermal Limitation?mentioning

confidence: 99%

Oxygen limited thermal tolerance in fish?

Pörtner

Mark

Bock

2004

Respiratory Physiology & Neurobiology

108

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In various phyla of marine invertebrates limited capacities of both ventilatory and circulatory performance were found to set the borders of the thermal tolerance window with limitations in aerobic scope and onset of hypoxia as a first line of sensitivity to both cold and warm temperature extremes. The hypothesis of oxygen limited thermal tolerance has recently been investigated in fish using a combination of non-invasive nuclear magnetic resonance (NMR) methodology with invasive techniques. In contrast to observations in marine invertebrates arterial oxygen tensions in fish were independent of temperature, while venous oxygen tensions displayed a thermal optimum. As the fish heart relies on venous oxygen supply, limited cardio-circulatory capacity is concluded to set the first level of thermal intolerance in fish. Nonetheless, maximized ventilatory capacity is seen to support circulation in maintaining the width of thermal tolerance windows. The interdependent setting of low and high tolerance limits is interpreted to result from trade-offs between optimized tissue functional capacity and baseline oxygen demand and energy turnover co-determined by the adjustment of mitochondrial densities and functional properties to a species-specific temperature range. At temperature extremes, systemic hypoxia will elicit metabolic depression, thereby widening the thermal window transiently sustained especially in those species preadapted to hypoxic environments.

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“…That abiotic factors limit the distribution and abundance of species and that temperature affects net growth and reproduction in poikilotherms has a long history (von Liebig 1840, Shelford 1931, Andrewartha & Birch 1954, Huffaker et al 1971. The infl uence of weather on the control by natural enemies has been posited for the spotted alfalfa aphid [Therioaphis maculata (Buckton) (Homoptera: Aphididae)] (Force & Messenger 1964), olive scale [Parlatoria oleae (Colvée) (Hemiptera: Diaspididae)] (Huffaker & Kennett 1966), red scale [Aonidella aurantii (Maskell) (Hemiptera: Diaspididae)] , and others.…”

Section: Discussionmentioning

confidence: 99%

A regional analysis of weather mediated competition between a parasitoid and a coccinellid predator of oleander scale

Gutiérrez¹,

Pizzamiglio²

2007

Neotrop. Entomol.

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Análise Regional da Competição Mediada por Fatores Climáticos entre um Parasitóide e um CoccinelídeoPredador da Cochonilha-da-Espirradeira na Califórnia and a coccinellid predator (Rhysobius lophanthae (Blaisd.) (Coleoptera: Coccinellidae), was examined using a general weather-driven, tri-trophic, physiologically based age-mass structured demographic model. The model is of intermediate complexity and was parameterized using extensive laboratory data and fi eld observations from Albany, CA. Temperature-dependent physiological indices were estimated from the laboratory data and used to scale per capita growth, fecundity and survivorship rates from maximal values in a time varying environment. The tri-trophic model was integrated in a GIS (geographic information system) and the species dynamics examined across years and across the ecological zones of California. Field data and simulation results suggested the coccinellid predator was the most important regulating agent of oleander scale in the mild climate of Albany. However, multiple linear regression analysis of simulation data across all ecological zones of California shows that the parasitoid A. chilensis is the most important agent in suppressing oleander scale densities in warmer climates, while the predator R. lophanthae increases scale density an average of 9.7% across all regions.

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Some Concepts of Bioecology

Cited by 201 publications

References 0 publications

Climate change and temperature-dependent biogeography: oxygen limitation of thermal tolerance in animals

Climate change and temperature-dependent biogeography: oxygen limitation of thermal tolerance in animals

Oxygen limited thermal tolerance in fish?

A regional analysis of weather mediated competition between a parasitoid and a coccinellid predator of oleander scale

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