Organisms use incomplete information from local experience to assess the suitability of potential habitat sites over a wide range of spatial and temporal scales. Although ecologists have long recognized the importance of spatial scales in habitat selection, few studies have investigated the temporal scales of habitat selection. In particular, cues in the immediate environment may commonly provi...

Here we show that pathogen-mediated selection can influence the evolution of host longevity. Greater longevity can impair the fitness of host organisms subject to pathogen attack, by reducing the mortality rate of infected hosts and thus creating a larger and more persistent reservoir of disease, from which infection can spread to the healthy population. Where longer-lived and shorter-lived hos...

Numerous genes in diverse organisms have been shown to be under positive selection, especially genes involved in reproduction, adaptation to contrasting environments, hybrid inviability, and host-pathogen interactions. Looking for genes under positive selection in pathogens has been a priority in efforts to investigate coevolution dynamics and to develop vaccines or drugs. To elucidate the func...

Flexibility in adult body size allows generalist parasitoids to use many host species at a cost of producing a range of adult sizes. Consequently, host selection behaviour must also maintain a level of flexibility as adult size is related to capture efficiency. In the present study, we investigated covariance of two plastic traits--size at pupation and host size selection behaviour-using Aphidi...

Divergent habitat preferences can contribute to speciation, as has been observed for host-plant preferences in phytophagous insects. Geographic variation in host preference can provide insight into the causes of preference evolution. For example, selection against maladaptive host-switching occurs only when multiple hosts are available in the local environment and can result in greater divergen...

The extent to which pathogens maintain the extraordinary polymorphism at vertebrate Major Histocompatibility Complex (MHC) genes via balancing selection has intrigued evolutionary biologists for over half a century, but direct tests remain challenging. Here we examine whether a well-characterized epidemic of Mycoplasmal conjunctivitis resulted in balancing selection on class II MHC in a wild so...

Hepatitis C virus (HCV) displays high genetic diversity. Inter-host sequence variability may mainly reflect a neutral drift evolution. In contrast, intra-host evolution may be driven by an adaptive selection to host responses to infection. Here, HCV E2 intra-host evolution in two patients during the course and follow-up of successive treatments with IFN-alpha and IFN-alpha/ribavirin was investi...

The fate of a parasite with exclusively vertical transmission depends critically on its virulence, the magnitude of its negative impact on fitness of the infected host. Relaxation of natural selection within the host population should favour the parasite by reducing this impact. We studied the dynamics of the sigma virus, a vertically transmitted parasite of Drosophila melanogaster, within a ca...

The Red Queen hypothesis can explain the maintenance of host and parasite diversity. However, the Red Queen requires genetic specificity for infection risk (i.e., that infection depends on the exact combination of host and parasite genotypes) and strongly virulent effects of infection on host fitness. A European crustacean (Daphnia magna)--bacterium (Pasteuria ramosa) system typifies such speci...