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M. Doebeli 《Population Ecology》2002,44(2):59-70
Understanding mechanisms of evolutionary diversification is central to evolutionary biology. Microbes constitute promising
model systems for observing processes of diversification directly in the laboratory. One of the main existing paradigms for
microbial diversification is the evolution of cross-feeding polymorphisms, in which a strain specializing on a primary resource
coexists with a cross-feeding strain that specializes on a waste product resulting from consumption of the primary resource.
Here I propose a theoretical model for the evolutionary dynamics through which cross-feeding polymorphisms can gradually emerge
from a single ancestral strain. The model is based on the framework of adaptive dynamics, which has proved to be very useful
for studying adaptive processes of divergence under sympatric conditions. In particular, the phenomenon of evolutionary branching
serves as a general paradigm for diversification. I show that evolutionary branching naturally occurs in evolutionary models
of cross-feeding if (1) there is a trade-off between uptake efficiencies on the primary and secondary resources, and (2) this
trade-off has positive curvature. The model also suggests that the evolution of cross-feeding should be more likely in chemostat
cultures than in serial batch cultures, which conforms with empirical observations. Overall, the model provides a theoretical
metaphor for the evolution of cross-feeding polymorphisms.
Received: February 19, 2002 / Accepted: May 8, 2002 相似文献
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We report the production of two types of siderophores namely catecholate and hydroxamate in modified succinic acid medium
(SM) from Alcaligenes faecalis. Two fractions of siderophores were purified on amberlite XAD, major fraction was hydroxamate type having a λmax at 224 nm and minor fraction appeared as catecholate with a λmax of 264 nm. The recovery yield obtained from major and minor fractions was 297 and 50 mg ml−1 respectively. The IEF pattern of XAD-4 purified siderophore suggested the pI value of 6.5. Cross feeding studies revealed
that A. faecalis accepts heterologous as well as self (hydroxamate) siderophore in both free and iron complexed forms however; the rate of
siderophore uptake was more in case of siderophores complexed to iron. Siderophore iron uptake studies indicated the differences
between hydroxamate siderophore of A. faecalis and Alc E, a siderophore of Alcaligenes eutrophus. 相似文献
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