No abstract

For over 150 years, ecologists have been striving to explain fundamental patterns of biological diversity, such as the observation that communities invariably consist of common and rare species, and to unravel the processes that underpin these patterns. This task is increasingly urgent given the accelerating loss of biological diversity. Although fishes are the most diverse vertebrate taxon and fish communities occur in a wide range of habitats, they have been relatively little studied in the quest to elucidate the processes that shape patterns of biological diversity. Here, some of the topics that investigations of fish assemblages can illuminate are highlighted. These include the characteristics of ecological communities and the role that dispersal limitation plays in structuring them, the distinction between core and occasional species, the insights that evaluating abundance in different currencies can bring and the assessment of community capacity. Questions are identified that future investigations of fish communities might tackle and a case study of a biodiverse ecoregion (Thailand and Peninsula Malaysia) is used to illustrate the need for better links between these ecological questions and effective conservation practice.

No abstract

The cryptic invasion of North American aquatic ecosystems by non-native haplotypes of Phragmites australis (Cav.) Trin. ex Steud., 1841, has been well documented. Most research has focused on eastern Canada, and the eastern seaboard, St. Lawrence waterway, southwest (Utah), and Gulf coast regions of the United States. Less has been published on the extent of this invasion in the north central United States. In this report, 69 populations of Phragmites australis were identified and sampled within the Minnesota and Mississippi River corridors of Minnesota, as well as from roadway drainage ditches within the greater Minneapolis-St. Paul metropolitan region (MSP). Restriction fragment length polymorphism analysis and DNA sequencing were used to determine the cpDNA lineage of each population. All populations sampled within the river valleys were native North American haplotype E, as were most MSP populations. However, numerous isolated populations of Eurasian haplotype M Phragmites australis were identified along MSP transportation corridors. Nuclear microsatellites indicated that these M haplotype populations are not clonal. These results show that Eurasian haplotype M Phragmites australis has become established in at least one region of Minnesota, but has not yet widely invaded the riparian wetlands of Minnesota's two largest rivers. This provides a baseline for continued monitoring of the spread of this invasive plant.