Intrinsic rate of natural increase: The relationship with body size

SummaryThe relationship between previously published values of “the intrinsic rate of natural increase” (rm) and body weight is studied. When organisms covering a wide range of body weights are compared, a correlation is found which can be described by the equation rm=aWn where rm is the intrinsic rate of natural increase per day and W is the average body weight in grams; a is a constant which takes three different values for unicellular organisms and heterotherm and homoiotherm animals respectively. The constant n has a value of about-0.275 for all three groups. This result is compared to the previously found relationship between the metabolic rate per unit weight and body size. It is shown that rm can be inter-preted as the productivity of an exponentially growing population and thus must correlate with metabolic rate. The values of the constants a and n, however, show that for each of the three groups, unicellular organisms, heterotherms and homoiotherms the ratio of energy used for maintenance to that used for production increases with increasing body size and that the evolution from protozoa to metazoa and the evolution from heterotherm to homoiotherm animals in both cases resulted in not only an increased metabolic rate, as shown previously, but also in a decreased population growth efficiency. It is shown that the increase in reproductive potential of homoiotherms relative to that of heterotherms is due to a shorter prereproductive period in the former group.Previous estimates of rm for different species and comparisons between these values in relation to their ecology are discussed in context with the found “rm-body weight” relationship. Attempts to show that such comparisons will be more meaningful when body size is included in the considerations are made. It is suggested that the found relationship may represent the maximum values rm can take rather than average values for all species, since it is likely that the species used for laboratory population-studies are biased in favor of species with high reproductive potentials.

[1]  D. B. Mertz.  The Mathematical Demography of the California Condor Population , 1971, The American Naturalist.

[2]  William H. Bossert,et al.  Life Historical Consequences of Natural Selection , 1970, The American Naturalist.

[3]  P. H. Leslie,et al.  The Intrinsic Rate of Natural Increase of Tribolium Castaneum Herbst. , 1949 .

[4]  S. Hemmingsen,et al.  Energy metabolism as related to body size and respiratory surfaces, and its evolution , 1960 .

[5]  E. Zeuthen.  Body size and metabolic rate in the animal kingdom : with special regard to the marine micro-fauna , 1947 .

[6]  R. B. Root.  An Estimate of Intrinsic Rate of Natural Increase in the Planarian, Dugesia Tigrina , 1960 .

[7]  A. Palissa.  Petrusewicz, K. & Macfadyen, A.: Productivity of Terrestrial Animals — Principles and Methods. IBP Handbook No. 13. — Oxford und Edinburgh (Blackwell Scientific Publications) 1970; 190 S., 28 Abb.; 50 s , 1971 .

[8]  L. C. Cole.  The Population Consequences of Life History Phenomena , 1954, The Quarterly Review of Biology.

[9]  R H Macarthur,et al.  SOME GENERALIZED THEOREMS OF NATURAL SELECTION. , 1962, Proceedings of the National Academy of Sciences of the United States of America.

[10]  C. E. King.  Food, Age, and the Dynamics of a Laboratory Population of Rotifers , 1967 .

[11]  J. Roughgarden.  Density‐Dependent Natural Selection , 1971 .

[12]  L. Birch,et al.  The intrinsic rate of natural increase of an insect population , 1948 .

[13]  Frederick E. Smith,et al.  Population Dynamics in Daphnia magna and a New Model for Population Growth , 1963 .

[14]  A. Macfadyen,et al.  Productivity of Terrestrial Animals: Principles and Methods , 1970 .

[15]  Eric R. Pianka,et al.  On r- and K-Selection , 1970, The American Naturalist.

[16]  P. H. Leslie.  THE INTRINSIC RATE OF INCREASE AND THE OVERLAP OF SUCCESSIVE GENERATIONS IN A POPULATION OF GUILLEMOTS (URIA AALGE PONT.) , 1966 .

[17]  A. Heron.  Population ecology of a colonizing species: The pelagic tunicate Thalia democratica , 1972, Oecologia.

[18]  H. G. Baker,et al.  Selection for colonizing abilitty. , 1965 .

[19]  W. Oliff.  The Mortality, Fecundity and Intrinsic Rate of Natural Increase of the Multimammate Mouse, Rattus (M-astomys) natalensis (Smith) in the Laboratory. , 1953 .

[20]  M. Cody,et al.  A GENERAL THEORY OF CLUTCH SIZE , 1966, Evolution; international journal of organic evolution.

[21]  A. E. Stiven.  The Effect of Temperature and Feeding on the Intrinsic Rate of Increase of Three Species of Hydra , 1962 .

[22]  A. Heron.  Population ecology of a colonizing species: The pelagic tunicate Thalia democratica , 1972, Oecologia.

[23]  T. D. Brock.  Principles of microbial ecology , 1967 .

[24]  N. Hairston,et al.  Natural selection and the parameters of population growth. , 1970 .

[25]  W. Schwartz.  Thomas D. Brock, Principles of Microbial Ecology. XIV und 306 S., 50 Abb., 35 Tab. Englewood Cliffs, N.J. 1966: Prentice Hall Inc. $ 7,75 , 1968 .

[26]  P. H. Leslie.  On the use of matrices in certain population mathematics. , 1945, Biometrika.

[27]  Madhav Gadgil,et al.  The Concept of r- and K-Selection: Evidence from Wild Flowers and Some Theoretical Considerations , 1972, The American Naturalist.

[28]  L. Birch,et al.  Experimental Background to the Study of the Distribution and Abundance of Insects: I. The Influence of Temperature, Moisture and Food on the Innate Capacity for Increase of Three Grain Beetles , 1953 .

[29]  P. Frank,et al.  Vital Statistics of Laboratory Cultures of Daphnia pulex DeGeer as Related to Density , 1957, Physiological Zoology.

[30]  T. Fenchel.  The ecology of marine microbenthos III. The reproductive potential of ciliates , 1968 .

[31]  J. Lawton,et al.  Annual Production and Respiration in Animal Populations , 1970, Nature.

[32]  L. Lefkovitch.  Census Studies on Unrestricted Populations of Lasioderma serricorne (F.) (Coleoptera: Anobiidae) , 1963 .

[33]  B. Clarke.  Density-Dependent Selection , 1972, The American Naturalist.

[34]  R. Dewitt.  The Intrinsic Rate of Natural Increase in a Pond Snail (Physa gyrina Say) , 1954, The American Naturalist.

[35]  F. Evans,et al.  The Intrinsic Rate of Natural Increase for the Human Louse, Pediculus humanus L. , 1952, The American Naturalist.