No selection on immunological markers in response to a highly virulent pathogen in an Arctic breeding bird

Abstract

In natural populations, epidemics provide opportunities to look for intense natural selection on genes coding for life history and immune or other physiological traits. If the populations being considered are of management or conservation concern, then identifying the traits under selection (or ‘markers’) might provide insights into possible intervention strategies during epidemics. We assessed potential for selection on multiple immune and life history traits of Arctic breeding common eiders (Somateria mollissima) during annual avian cholera outbreaks (summers of 2006, 2007 & 2008). We measured prelaying body condition, immune traits, and subsequent reproductive investment (i.e., clutch size) and survival of female common eiders and whether they were infected with Pasteurella multocida, the causative agent of avian cholera. We found no clear and consistent evidence of directional selection on immune traits; however, infected birds had higher levels of haptoglobin than uninfected birds. Also, females that laid larger clutches had slightly lower immune responses during the prelaying period reflecting possible downregulation of the immune system to support higher costs of reproduction. This supports a recent study indicating that birds investing in larger clutches were more likely to die from avian cholera and points to a possible management option to maximize female survival during outbreaks.

Injecting epidemiology into population viability analysis: avian cholera transmission dynamics at an arctic seabird colony

“…An alternative approach, which may be more logistically feasible and cost‐effective, is for managers to actively encourage nesting birds to their abandon their eggs at the first sign of avian cholera mortality (Legagneux et al . ). Most colonial nesting seabirds disperse when their eggs are lost and by inducing migration away from the colony individuals could be moved from a location of high density and elevated disease transmission probability to a location of low density and lower disease transmission probability.…”

“…; Legagneux et al . ). However, this must be balanced against the possibility that efforts to reduce transmission are counterproductive if they only hinder natural selection for disease resistance (Staszewski & Boulinier ).…”

“…() and Legagneux et al . (), we assumed that eiders found dead on the colony died due to avian cholera.…”

Corticosterone, inflammation, immune status and telomere length in frigatebird nestlings facing a severe herpesvirus infection

“…Second, the immune traits we have measured in our study might not have been responsive to this specific infection. Given the several mechanisms involved in the immune response, the simultaneous use of multiple immune metrics might help to cover the complexity of the immune system (Legagneux et al ., 2014). Although the levels of complement and natural antibodies are amongst the most used in avian immunology, it would be interesting in future work to include additional markers, such as heterophile-to-lymphocyte ratio, avian immunoglobulin and basophils (Legagneux et al ., 2014).…”

Avian Cholera emergence in Arctic-nesting northern Common Eiders: using community-based, participatory surveillance to delineate disease outbreak patterns and predict transmission risk

“…Such action requires early detection and prompt response by trained individuals to ensure safe and effective disposal. An alternative approach, raised by Legagneux et al (2014), is to actively encourage nesting birds to abandon their eggs at the first sign of Avian Cholera mortality and thereby induce movement away from affected locations. This tactic relies on the species tendency to return to the same nesting location each year (Goudie et al 2000), in effect sacrificing current year productivity to decrease pathogen exposure and enhance adult survivorship.…”