Infection genetics and the likelihood of host shifts in coevolving host-parasite interactions.

Identifying factors that promote host shifts is crucial for understanding the origin and maintenance of biodiversity as well as the emergence of novel infectious diseases. Previous research has demonstrated that the opportunity for cross-species transmission and parasite adaptation can play an important role in determining if and when a host shift occurs. Another possibility is that the genetic basis of infection and resistance, when coupled with the process of coevolution (i.

Influence of toxic cyanobacteria on community structure and microcystin accumulation of freshwater molluscs.

Community structure and microcystin accumulation of freshwater molluscs were studied before and after cyanobacterial proliferations, in order to assess the impact of toxic blooms on molluscs and the risk of microcystin transfer in food web. Observed decrease in mollusc abundance and changes in species richness in highly contaminated waters were not significant; however, relative abundances of taxa (prosobranchs, pulmonates, bivalves) were significantly different before and after cyanobacterial bloom. Pulmonates constituted the dominant taxon, and bivalves never occurred after bloom.

The evolution of specificity in evolving and coevolving antagonistic interactions between a bacteria and its phage.

The evolution of exploitative specificity can be influenced by environmental variability in space and time and the intensity of trade-offs. Coevolution, the process of reciprocal adaptation in two or more species, can produce variability in host exploitation and as such potentially drive patterns in host and parasite specificity. We employed the bacterium Pseudomonas fluorescens SBW25 and its DNA phage Phi2 to investigate the role of coevolution in the evolution of phage infectivity range and its relation with phage growth rate.

The impact of migration from parasite-free patches on antagonistic host-parasite coevolution.

Natural populations of hosts and parasites are often subdivided and patchily distributed such that some regions of a host species' range will be free from a given parasite. Host migration from parasite-free to parasite-containing patches is expected to alter coevolutionary dynamics by changing the evolutionary potential of antagonists. Specifically, host immigration can favor parasites by increasing transmission opportunities, or hosts by introducing genetic variation.

Variation in the response of the invasive species Potamopyrgus antipodarum (Smith) to natural (cyanobacterial toxin) and anthropogenic (herbicide atrazine) stressors.

In the context of increasing freshwater pollution, the impact on life-traits (survival, growth and fecundity) and locomotion of Potamopyrgus antipodarum of a 5-week field-concentration exposure to the cyanobacterial toxin microcystin-LR and the triazine herbicide, atrazine was studied. Whatever the age of exposed snails (juveniles, subadults, adults), microcystin-LR induced a decrease in survival, growth and fecundity but had no effect on locomotion. Atrazine induced a decrease in locomotory activity but had no significant effect on the life-traits.