排序方式: 共有12条查询结果,搜索用时 46 毫秒
11.
Kyle A. Young Jessica Stephenson Alexandre Terreau Anne-Flore Thailly Gonzalo Gajardo Carlos Garcia de Leaniz 《Biological invasions》2009,11(8):1955-1961
We used an invaded stream fish community in southern Chile to experimentally test whether the diversity of exotic species
affects their competitive impact on a native species. In artificial enclosures an established invasive, rainbow trout, Oncorhynchus mykiss, and a potential invader, Atlantic salmon, Salmo salar, reduced the growth rate of native peladilla, Aplochiton zebra, by the same amount. In enclosures with both exotic salmonids, the growth rates of all three species were the same as in
single exotic treatments. While neither species identity nor diversity appeared to affect competitive interactions in this
experiment, the impact of salmonid diversity may vary with the type of interspecific interaction and/or the species identity
of the exotics. Our experiment links two prominent concepts in invasion biology by testing whether the result of invasional
meltdown, an increase in the diversity of exotic species, affects their impact through interspecific competition, the mechanism
invoked by the biotic resistance hypothesis. 相似文献
12.
The release of an increasing number of complete bacterial genomic sequences allows the evolutionary analysis of processes such as regulatory networks. CtrA is a response regulator of the OmpR subfamily, belonging to a complex regulatory network in the dimorphic bacterium Caulobacter crescentus. It coordinates the cell cycle with an asymmetric division, which is part of the adaptation of Caulobacter to poor-nutrient environments. CtrA is only found in alpha-proteobacteria, a group of bacteria encompassing genera with very distinct lifestyles, including host-associated bacteria. Analyses of CtrA regulatory networks and morphological examinations of some alpha-proteobacteria are presented. Our observations suggest that the core of the CtrA regulation network is conserved and that alpha-proteobacteria divide asymmetrically. We propose that the two daughter cells might be differentiated bacteria, each one displaying specific functions. 相似文献