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Preliminary Models for Growth Rates in Altricial Birds
Author(s) -
Ricklefs Robert E.
Publication year - 1969
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1936894
Subject(s) - altricial , growth rate , biology , brood , ecology , offspring , function (biology) , precocial , productivity , growth curve (statistics) , zoology , econometrics , economics , evolutionary biology , mathematics , pregnancy , genetics , geometry , macroeconomics
The rate of growth in body weight of birds is not correlated with nestling mortality, but rather is a function of the adult body size of the species and the mode of development of the young. To examine the adaptive basis of growth rates, models are formulated which incorporate the mortality of the young, their energy requirement and their rate of growth into a function which determines the productivity of offspring. This function is maximized when growth rate occurs as rapidly as possible, at the expense of brood size. Optimally, one young should be raised which grows as rapidly as the parents are able to supply food. Because this is not observed in nature, and because of other inefficiencies due to the form of the growth curve, it is postulated that physiological constraints, based on the functional organization of the body plan, limit growth rate. This may occur either through bottlenecks placed on the rate at which food can be processed and utilized, or by problems of allocation of energy and tissues among mature and embryonic functions.