TY - JOUR A1 - Hovestadt, Thomas A1 - Thomas, Jeremy A. A1 - Mitesser, Oliver A1 - Schönrogge, Karsten T1 - Multiple host use and the dynamics of host-switching in host-parasite systems JF - Insect Conservation and Diversity N2 - The link between multi‐host use and host switching in host–parasite interactions is a continuing area of debate. Lycaenid butterflies in the genus Maculinea, for example, exploit societies of different Myrmica ant species across their ranges, but there is only rare evidence that they simultaneously utilise multiple hosts at a local site, even where alternative hosts are present. We present a simple population‐genetic model accounting for the proportion of two alternative hosts and the fitness of parasite genotypes on each host. In agreement with standard models, we conclude that simultaneous host use is possible whenever fitness of heterozygotes on alternative hosts is not too low. We specifically focus on host‐shifting dynamics when the frequency of hosts changes. We find that (i) host shifting may proceed so rapidly that multiple host use is unlikely to be observed, (ii) back and forth transition in host use can exhibit a hysteresis loop, (iii) the parasites' host use may not be proportional to local host frequencies and be restricted to the rarer host under some conditions, and (iv) that a substantial decline in parasite abundance may typically precede a shift in host use. We conclude that focusing not just on possible equilibrium conditions but also considering the dynamics of host shifting in non‐equilibrium situations may provide added insights into host–parasite systems. KW - Host-parasite interaction KW - Maculinea butterfly KW - Myrmica ant non-equilibrium dynamics KW - population genetics Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-204747 VL - 12 IS - 6 ER - TY - JOUR A1 - Biju, Joseph A1 - Schwarz, Roland A1 - Linke, Burkhard A1 - Blom, Jochen A1 - Becker, Anke A1 - Claus, Heike A1 - Goesmann, Alexander A1 - Frosch, Matthias A1 - Müller, Tobias A1 - Vogel, Ulrich A1 - Schoen, Christoph T1 - Virulence Evolution of the Human Pathogen Neisseria meningitidis by Recombination in the Core and Accessory Genome JF - PLoS One N2 - Background Neisseria meningitidis is a naturally transformable, facultative pathogen colonizing the human nasopharynx. Here, we analyze on a genome-wide level the impact of recombination on gene-complement diversity and virulence evolution in N. meningitidis. We combined comparative genome hybridization using microarrays (mCGH) and multilocus sequence typing (MLST) of 29 meningococcal isolates with computational comparison of a subset of seven meningococcal genome sequences. Principal Findings We found that lateral gene transfer of minimal mobile elements as well as prophages are major forces shaping meningococcal population structure. Extensive gene content comparison revealed novel associations of virulence with genetic elements besides the recently discovered meningococcal disease associated (MDA) island. In particular, we identified an association of virulence with a recently described canonical genomic island termed IHT-E and a differential distribution of genes encoding RTX toxin- and two-partner secretion systems among hyperinvasive and non-hyperinvasive lineages. By computationally screening also the core genome for signs of recombination, we provided evidence that about 40% of the meningococcal core genes are affected by recombination primarily within metabolic genes as well as genes involved in DNA replication and repair. By comparison with the results of previous mCGH studies, our data indicated that genetic structuring as revealed by mCGH is stable over time and highly similar for isolates from different geographic origins. Conclusions Recombination comprising lateral transfer of entire genes as well as homologous intragenic recombination has a profound impact on meningococcal population structure and genome composition. Our data support the hypothesis that meningococcal virulence is polygenic in nature and that differences in metabolism might contribute to virulence. KW - population genetics KW - DNA recombination KW - meningococcal disease KW - recombinant proteins KW - genomic databases KW - comparative genomics KW - neisseria meningitidis KW - homologous recombination Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-137960 VL - 6 IS - 4 ER -