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991.
992.
The architecture of termite mounds: a result of a trade-off between thermoregulation and gas exchange? 总被引:2,自引:1,他引:1
We examined the influence of gas exchange on the architectureof termite
mounds. In Comoé National Park
(Côted'Ivoire), Macrotermes
bellicosus builds, as an adaptation toambient temperature conditions,
differently shaped mounds inthe shrub savanna and the gallery forest.
Previous studies suggestedthat there might be a constraint that limits the
degree of thermalinsulation of the interior (i.e., nest) of the mounds in
environmentswith relatively low ambient temperatures. This factor causes,in
proximate terms, suboptimal low nest temperatures and ultimatelyleads to
reduced reproductive success in the gallery forest.In this study, we examined
whether the necessity for gas exchangemight constrain mound architecture. We
measured CO2 concentrationsin the air channels of mounds in
different habitats and undermanipulated temperature regimes. During both the
dry and therainy season we found higher CO2 concentrations in
mounds ofthe gallery forest than in mounds of the savanna. Additional
measurementsin forest mounds, architecturally resembling those of the savanna
dueto an experimental increase in ambient temperatures, revealedlower
CO2 concentrations than unmanipulated mounds in this habitat.
Generally,concentrations were higher during the rainy season comparedto the
dry season and lower during day than during night. Summarizingthese results
we present a model that illustrates this trade-offbetween thermoregulation
and gas exchange under different temperatureregimes. Both factors together
result in different mound architecturesunder different environmental
temperatures and may finally limitthe distribution of this species. 相似文献
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997.
Eduard v. Martens 《Journal of Ornithology》1866,14(1):5-31
Ohne Zusammenfassung 相似文献
998.
Eduard Uhlenhuth 《The Journal of general physiology》1919,1(4):473-482
1. Two substances are involved in amphibian metamorphosis as studied in Ambystoma opacum: first, iodine, which is taken up by the food, and second, an excretor substance, which is evolved during the processes of growth and serves to induce the excretory function of the thyroid gland. 2. This explains why in larvæ, whose metamorphosis is inhibited by lack of iodine, growth is checked at the time when metamorphosis should occur; for at this time the excretor substance commences to act and this results, if iodine is absent, in the excretion by the thyroid of toxic substances which cause the breakdown of proteins and consequently a decrease in size of the larvæ. 3. Larvæ whose metamorphosis is inhibited by extirpation of the thyroid or by the hereditary lack of a thyroid (as is the case in Typhlomolge) can grow normally, since in them the action of the excretor substance cannot result in the excretion by the thyroid of a toxic growth-inhibiting substance. 4. At low temperature less excretor substance is produced than at high temperature during an equal rate of growth; therefore larvæ kept at low temperature reach a larger size than larvæ kept at high temperature, before they metamorphose. 相似文献
999.
The Journal of Membrane Biology - Methods were developed for estimation of the area of the microscopic and ultramicroscopic surface of the toad bladder epithelium at various degrees of stretch.... 相似文献
1000.