Ecotypes and genetic structure of Rhinanthus alectorolophus (Orobanchaceae) in southwestern Germany

European annual species of the genus Rhinanthus often exhibit seasonal ecotypic variation, a phenomenon also known from related genera of hemiparasitic Orobanchaceae. Populations with different flowering times exist, correlated with differences in a number of morphological characters. The present study evaluates the correlation of morphological characters and genetic differentiation of populations of Rhinanthus alectorolophus. Thirty-nine populations of three different subspecies from southwestern Germany were sampled. A total of 798 individuals were used for morphological analyses and 187 of these for AFLP analyses. Principal component analysis showed that morphological variation is mostly continuous. In a discriminant analysis based on morphological characters, only 89.7 % of all individuals were correctly assigned to their previously determined subspecies, indicating that subspecies identification is ambiguous for some populations. Using AFLP data and Bayesian assignment analysis, the sampled individuals could be grouped in three genetic clusters which do not correspond to the three subspecies. Instead, the clustering shows a clear geographic pattern and a Mantel test likewise revealed a significant correlation between genetic and geographic distances. Correlations of genetic distances with differences in morphological characters were weak and mostly insignificant. The results indicate that the subspecies of R. alectorolophus do not form discrete entities and that the character combinations distinguishing them are homoplastic.

The Family Pasteurellaceae

This chapter describes the systematics and evolution of Pasteurellaceae with emphasis on new information generated since the 3rd edition of The Prokaryotes which only included chapters dealing with Haemophilus, Actinobacillus, and Pasteurella. A major source of new information for the current chapter has been provided by whole genome sequences now available for many taxa of the family. Some 100 species and species-like taxa have been documented and 18 genera of Pasteurellaceae reported so far. Members of the family include specialized commensals, potential pathogens, or pathogens of vertebrates and mainly survive poorly in other habitats including the external environment. The pathogenic members are of major importance to animal production and human health. Members of Pasteurellaceae have relatively small genomes, probably as a result of adaption to a special habitat. The most important species in veterinary microbiology include Pasteurella multocida, Actinobacillus pleuropneumoniae, [Haemophilus] parasuis, Mannheimia haemolytica, Bibersteinia trehalosi, and Avibacterium paragallinarum, while Haemophilus influenzae and Aggregatibacter actinomycetemcomitans represent the most important species as to human disease. Traditional isolation techniques are still used in both human and veterinary clinical diagnostic laboratories although genetically based diagnostic methods have replaced traditional biochemical/physiological methods for characterization and identification. For all species, MALDI-TOF can now be used as a diagnostic tool. As control and if MALDI-TOF equipment is not at hand, PCR-based specific detection is possible for Pasteurella multocida, Actinobacillus pleuropneumoniae, [Haemophilus] parasuis, Mannheimia haemolytica, Avibacterium paragallinarum, Gallibacterium anatis, Haemophilus influenzae, and Aggregatibacter actinomycetemcomitans. A lot of work has been directed towards identification of virulence factors and understanding host microbe interactions involved in disease.