e-journal

A new thermoregulatory index for heterothermy

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1. The controlled adjustment of body temperature (Tb) by animals in relation to ambient temperature (Ta), or
heterothermy, is a phenomenon that has a clear adaptive value. Heterothermy results in a substantial reduction
in energy expenditure and water loss, but it also incurs costs, such as the energy cost required for rewarming,
energy cost of excretion of metabolic wastes, delayed development of offspring and fitness costs of increased vulnerability
to predators. A general index quantifying heterothermy would be useful, since heterothermy is often
correlated with important physiological variables that determine fitness.
2. We used metabolic rate (MR), Tb and Ta to develop a thermoregulatory index (TRi), a continuous variable
that describes the thermoregulatory effort of animals. TRi is expressed by an equationwith two terms: the deviation
of actual heat gain/dissipation to heat gain/dissipation predicted by first principles and the temperature
dependence of metabolic reactions.
3. TRi can be interpreted as a measure of the amount of time an animal needs to generate an amount of heat,
estimated from physical principles, to reach a certain Tb along a temperature gradient.
4. TRi eliminates the need to define a threshold for Tb and can be used to compare positions of animals along a
thermoregulatory continuumwithin and among species of diverse taxonomic affiliation. In addition, TRi unveils
the relationship between the energy expended for thermoregulation and important physiological variables that
determine survival and reproduction. TRi requires knowledge ofMR, which may be a disadvantage since information
on MR for free-living animals may be difficult to obtain. However, with the advent of methods to measure
field metabolism, this impediment may be surmountable inmany species.

Key-words: body temperature, heterothermy, resting metabolic rate, thermoregulation index

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Informasi Detail

Judul Seri

Methods in Ecology and Evolution

No. Panggil

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Penerbit

: British Ecological Society., 2014

Deskripsi Fisik

Methods in Ecology and Evolution 2014, 5, 141–145

Bahasa

English

ISBN/ISSN

doi: 10.1111/2041-21

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

Bilogi

Info Detail Spesifik

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Pernyataan Tanggungjawab

Wati/Agus

Versi lain/terkait

Lampiran Berkas

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