MacLean R Craig, Bell Graham, Rainey Paul B
Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montreal, QC, Canada H3A 1B1.
Proc Natl Acad Sci U S A. 2004 May 25;101(21):8072-7. doi: 10.1073/pnas.0307195101. Epub 2004 May 18.
The evolution of ecological specialization is expected to carry a cost, due to either antagonistic pleiotropy or mutation accumulation. In general, it has been difficult to distinguish between these two possibilities. Here, we demonstrate that the experimental evolution of niche-specialist genotypes of the bacterium Pseudomonas fluorescens that colonize the air-broth interface of spatially structured microcosms is accompanied by pleiotropic fitness costs in terms of reduced carbon catabolism. Prolonged selection in spatially structured microcosms caused the cost of specialization to decline without loss of the benefits associated with specialization. The decline in the cost of specialization can be explained by either compensatory adaptation within specialist lineages or clonal competition among specialist lineages. These results provide a possible explanation of conflicting accounts for the cost of specialization.
由于拮抗多效性或突变积累,生态特化的进化预计会带来代价。一般来说,很难区分这两种可能性。在这里,我们证明,在空间结构微观世界的气-液界面定殖的荧光假单胞菌生态位特化基因型的实验进化,伴随着碳分解代谢降低方面的多效性适合度代价。在空间结构微观世界中的长期选择导致特化代价下降,同时又不会丧失与特化相关的益处。特化代价的下降可以通过特化谱系内的补偿性适应或特化谱系间的克隆竞争来解释。这些结果为关于特化代价的相互矛盾的说法提供了一种可能的解释。