Culture Media for Drosophila. I. Changes in Hydrogen Ion Concentration of the Medium

Pearl, Raymond; Penniman, W. B. D.

doi:10.1086/280106

Cited by 11 publications

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“…His survey shows that, since the universe of any species is limited, multiplication of animals must of itself restrict further population growth. We see evidence of such ' automatic ' limitation in the work of Richards (1934) and of Gause (1932) on yeasts, in Johnson's (1937) studies on protozoa, in Pearl's (1926) researches on Drosophila, in the investigations of Chapman (1928) and Park (1933) on Tribolium, in Crew & Mirskaia's (193 I) work with rats, and in more complex situations involving predator and prey (Gause, 1934) or parasite and host (Salt, 1934). This review of the literature also brings out how specific biological reactions, arising from reciprocal interaction between the individuals and their environment, may limit the growth of populations.…”

Section: Introductionmentioning

confidence: 90%

“…Indeed Stanley (1932) objects to Volterra's mathematics on these grounds: 'So many assumptions have been made in order to simplify the mathematical treatment, that the entities considered can nowhere be found in the roster of living organisms.' (I) Initial assumptions Verhulst (1839), Pearl (1926) and Kostitzin (1937) derive the logistic from two demographic assumptions which may be stated in general terms as follows: natality decreases and mortality increases with increased crowding. While the second is plausible, there is no clear reason for assuming the first.…”

Section: Biological Assumptions Inherent I N Current Theories O F Popmentioning

confidence: 99%

“…I) fit a logistic for any reason other than the choice of the right time at which to add food and the right amount of it. Pearl's (1926) data refer only to the adult flies present in his cultures: they make no reference to the larvae and pupae, which are rated as equivalent to the unborn in human populations. Consequently the thesis Pearl puts forward is valid only in so far as this analogy with human populations is correct.…”

Section: I93mentioning

confidence: 99%

“…It will be clear from the preceding paragraph that the form of argument by analogy implicit in Pearl's (1926) statements is misleading in at least two respects. First, the developmental stages of the fly are not equivalent to the 'embryos', 'young children', 'older children' and 'adults' found in human populations, either in a demographic sense or in the way they occupy and use their total environment.…”

Section: Population Growth In Drosophila Culturesmentioning

confidence: 99%

“…The logistic growth of the adult population in a Drosophilu culture to which extra food was added after 18 days. FromPearl (1926).…”

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confidence: 99%

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Population Growth in Drosophila Cultures

Sang¹

1950

Biological Reviews

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Summary .1. As Pearl (1926) recognized, the Drosophila culture can be taken as a model of population growth involving the interaction of a plant and an animal species. Early work suggested that the growth of the fly population could be adequately described by an S‐shaped curve of the kind previously applied by Verhulst (1839) to human populations. This curve, the logistic, shows that populations apparently possess: (a) a slow initial growth rate, which (b) increases until it reaches a maximum (the point of inflexion of the curve), and (c) then becomes progressively less as the population approaches the maximal size possible under the particular ecological conditions. This logistic law was subsequently widely applied to a variety of populations, from bacterial to human, developing under divers conditions. Part of the justification for this procedure derived from the apparently fundamental character of the Drosophila model, and this review is devoted to an examination of that assumption. 2. The mathematical derivation of the Pearl‐Verhulst logistic law is shown to rest on highly arbitrary postulates which are not supported even by the early experimental analysis of the circumstances influencing natality and mortality in a Drosophila culture. Pearl and his co‐workers generally failed to recognize the importance of the growth of the yeast population, and, by paying attention only to the adult flies in their cultures, took no account of the contribution of the larvae and pupae present to the total population. As a consequence, their formulation of the experimental analysis was in terms of the intraspecific relationships between the adult individuals of Drosophila, and little weight was attached to the competition between larvae for food and space. 3. Examination of the total population (eggs, larvae, pupae, adults and yeasts) present in a culture shows that the logistic has sometimes been applied to family growth and not to true population growth, and that it describes even this restricted phase very incompletely. The precise course of population growth is found to depend upon the changes of egg output of the females, pre‐adult mortality and the duration of the various instars. Each of these is affected to some extent by the availability of the yeasts, and the growth and distribution of the yeasts is modified by the activity of the feeding larvae in the culture. That is, the interspecific relationship is found to be the primary ecological regulator of population growth; but the data from a total count are not sufficiently precise to permit a detailed analysis of this relationship. 4. While the course of oviposition of normal females is fairly regular under optimal conditions, their potential fecundity is more than halved when they are introduced into a normal culture bottle. This reduction in egg output results from a change in the character of the yeasts, a qualitative change, induced by the activity of the larvae in the medium. Since the yeasts change quantitatively and qualitatively as the culture grows, the early ...

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Section: Introductionmentioning

confidence: 90%

Section: Biological Assumptions Inherent I N Current Theories O F Popmentioning

confidence: 99%

Section: I93mentioning

confidence: 99%

Section: Population Growth In Drosophila Culturesmentioning

confidence: 99%

“…The logistic growth of the adult population in a Drosophilu culture to which extra food was added after 18 days. FromPearl (1926).…”

mentioning

confidence: 99%

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Population Growth in Drosophila Cultures

Sang¹

1950

Biological Reviews

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An experimental study of environmental factors in selection and population

Harnly¹

1929

J. Exp. Zool.

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The following experiments with Drosophila melanogaster were planned to study the effects of four environmental factors on a mixed population. Varying the environmental conditions under which the larvae developed would be expected to show to what'extent these factors affect the total yield and also the ratio of the types to each other. METHODSAll experiments were carried out in incubators at approximately 25°C. The food was the customary banana-agar mixture in the proportion of 500 grams of banana, 500 cc. of water, and 10 grams of agar-agar. The bananas were always overripe (the skins dark brown or black), but not decayed. The amount of yeast used varied with the a r e a -o n e drop of a yeast suspension (one cake of fresh yeast mixed with 100 cc. of water) was used in vials, two drops in 4-ounce bottles, four drops in half-pint and pint milk bottles, and six drops in 250-cc. Erlenmeyer flasks.Virgin wild females of a particular inbred stock (wildtype flies from the Star Dichaete stock) were crossed to vestigial males. Virgin F, females were backcrossed to vestigial males. The use of the backcross assures equal numbers of two kinds of eggs being deposited in each culture. A

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Die Beeinflussung der Vitalit�t durch multiple Allele, untersucht an vestigial-allelen von Drosophila melanogaster

Lüers¹

1935

W. Roux' Archiv f. Entwicklungsmechanik

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Culture Media for Drosophila. I. Changes in Hydrogen Ion Concentration of the Medium

Cited by 11 publications

References 0 publications

Population Growth in Drosophila Cultures

Population Growth in Drosophila Cultures

An experimental study of environmental factors in selection and population

Die Beeinflussung der Vitalit�t durch multiple Allele, untersucht an vestigial-allelen von Drosophila melanogaster

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