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Origin and Development of Endothermy: From the Standpoint of Ecological Energetics of Birdsстатья
- Автор: Gavrilov Valery M.
- Сборник: Recent Progress in Microbiology and Biotechnology
- Том: 3
- Глава в коллективной монографии
- Год издания: 2020
- Место издания: Book Publisher International a part of SCIENCEDOMAIN International)
- Первая страница: 131
- Последняя страница: 154
- Номер статьи: 12
- DOI: 10.9734/bpi/rpmb/v3
- Аннотация: The study is based on the results of the integrated measurement of the energy expenditure at rest and common activity in birds belonging to various systematic groups that display considerable variation in their phylogenesis, specific features of ecology and feeding, locomotor methods, and body sizes. We believe that the emergence of homoiothermy was directly associated with the development of high activity due to the aerobic metabolism. The standard metabolism of the extant birds and mammals is over one order of magnitude higher than poikilotherms of equal size. This high level of heat production, in combination with low heat conductance, is the basis for homoiothermy. Heat conductance is a result of the interactions between vasomotor and pilomotor responses. The differences in the level of heat production by one order of magnitude are present, even when the body temperature of poikilotherms reaches the same values as in homoiotherms. The maintenance of homoiothermy is energetically expensive and requires considerably higher level of food consumption as compared with poikilotherms. It is rather unlikely that such an increase in metabolism developed in phylogenesis only for the sake of thermoregulation, especially at the earliest stages in the evolution of homoiothermy, when it was inefficient to maintain thermal stability. This is also highly improbable, since homoiotherms developed in the early Mesozoic era, which was the warmest and most thermostable period in the history of the Earth. Thermoregulation is a side effect of the increase in aerobic capacity. We believe that an increase in the aerobic capacity, which leads to an increase in activity, was the major selective factor that formed the background for the development of homoiothermy. The selective advantage of elevated activity may be considered to be a major condition for the survival and reproduction of homoiotherms. An advantage of birds and their ancestors with higher energetics can easily be explained in terms of selection; they are able to maintain higher flying speed and cover larger distances when searching for food and, in defensive behavior, will better protect their area and occupy new sites, as well as succeed in courting and reproduction. Despite an increase in the energetic cost for existence, these advantages are also important, since increased minimal capacity makes it possible to correspondingly elevate the energy input for meeting new energetic demands.
- Добавил в систему: Гаврилов Валерий Михайлович