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An Experimental Analysis of a Life History Theory
Author(s) -
Luckinbill Leo S.
Publication year - 1984
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1938325
Subject(s) - biology , adaptation (eye) , competition (biology) , selection (genetic algorithm) , density dependence , ecology , growth rate , population density , population , evolutionary biology , demography , mathematics , geometry , artificial intelligence , neuroscience , sociology , computer science
r— and K—selection were applied to bacterial populations for up to 400 generations in the form of density—independent or density—dependent population controls in both batch and semi—continuous culture. Shifting ratios of competitively neutral genetic markers signaled the adaptation of bacterial strains to selection. Pairwise competition of r— with K—adapted strains showed adaptation under density—dependent and independent and independent controls to be nonspecific; that is, the adaptive trade—off predicted in theory did not occur here. R— and K—selection only adapted populations to the same thing; growth. Predicted adaptations in growth rate, saturation density, cell size, productivity, and efficiency also did not occur. These bacteria, however, were found to have the ability both to grow rapidly and exploitatively, or alternatively to survive up to 7 wk starvation at high density. The latter mechanism, allowing survival through prolonged periods of intense resource deprivation, is clearly a K type of adaptation. E. Coli appears to have hedged its environmental bets by the capacity for either rapid growth and exploitation, or persistence in the face of depleted resources, as the situation demands.