Costs of reproduction in a long-lived bird: Large clutch size is associated with low survival in the presence of a highly virulent disease

Department of Biology, Carleton University, Ottawa, Ontario, Canada K1A0H3.
Biology letters (Impact Factor: 3.25). 05/2009; 5(2):278-81. DOI: 10.1098/rsbl.2008.0704
Source: PubMed


Fitness costs of reproduction are expected to be more pronounced when the environmental conditions deteriorate. We took advantage of a natural experiment to investigate the costs of reproduction among common eiders (Somateria mollissima) nesting at a site in the Arctic, where an avian cholera epizootic appeared at different magnitudes. We tested the predictions that larger reproductive effort (clutch size) is associated with lower survival or breeding probability the following year, and that this relationship was more pronounced under heightened exposure to the disease. Our results indicate that large clutch sizes were associated with lower survival of female eider ducks, but only when there was heightened exposure to avian cholera, as indexed by eider mortality on site. No cost was observed when cholera was absent or when lesser exposure was evident. This supports the hypothesis that fitness costs of high reproductive effort are higher under unfavourable conditions such as a disease epizootic, and further indicates that being a conservative breeder can increase survival probability, given the presence of a highly virulent disease.

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Available from: Mark Randall Forbes, Oct 04, 2015
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    • "Similar results were found in at least two bird species using brood or clutch size manipulation ; individuals with increased parental care exhibited lower levels of antibodies or complement (Deerenberg et al. 1997; Berzins et al. 2011). Because immune traits considered here do not seem to mediate any prominent mechanisms affecting survival, we conclude that eiders may be more affected by avian cholera because of egg production and/or incubating larger clutches (Descamps et al. 2009) than by a slight reduction of their specific immunocompetence at the onset of reproduction . This reflects possible downregulation of the immune system to support higher costs of reproduction (Norris and Evans 2000). "
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    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.
    Evolutionary Applications 06/2014; 7(7). DOI:10.1111/eva.12180 · 3.90 Impact Factor
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    • "In wild populations, when foraging conditions are poor, malnourished post-spawning fish may suffer high mortality (Dutil and Lambert, 2000), likely higher than in our study which provided ample feeding opportunities and controlled environmental conditions year round. Interactions between environmental conditions (temperature and food supply) and metabolic performance presumably act as a function of season, year and life history strategy, such that under some unfavorable environmental conditions, reproduction would lead to high mortality, whereas in favorable years it might remain unaffected (Descamps et al., 2009; Gustafsson et al., 1994; Lambert and Dutil, 2000). Accurately assessing the age-specific abundance of immature and mature fish in exploited populations can be problematic, but is necessary for evaluating the survival cost of reproduction from long-term fishery databases (Beverton et al., 2004). "
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    ABSTRACT: Despite increasing interest in optimal life history theory and the associated physiological, ecological and evolutionary processes, little information exists on gonad–soma tradeoffs and longevity of individuals over long time periods. We examined somatic and survival costs of reproduction in captive iteroparous, batch-spawning Atlantic cod (Gadus morhua), utilizing diploids and triploids, knowing that triploid females invest little to no energy into gametogenesis. Based on annual specific growth rate, there was no evidence for a somatic cost of reproduction at ages 2 (virgin year) and 4 years, but there was at age 3 years. At age 2 years, low investment in reproduction likely accounted for the lack of a somatic cost of reproduction, whereas at age 4 the absence was associated with heightened growth post-spawning enabling mature fish to catch up to immature fish. At age 3, compensatory growth during post-spawning was below that of immature fish. Survival represented a significant component of the cost of reproduction. Laboratory experiments examining the cost of reproduction have traditionally focused on shorter time periods, commonly spanning several months, whereas ours spanned nearly four years. Although previously done for bivalves, to our knowledge, this is the first time the cost of reproduction has been evaluated using triploid fish as a comparator.
    Journal of Experimental Marine Biology and Ecology 02/2014; 451:35–43. DOI:10.1016/j.jembe.2013.10.030 · 1.87 Impact Factor
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    • "challenges involved in attaining the required resources. For example , whereas female eiders laying large clutches generally show higher survival than those laying smaller ones (Yoccoz et al., 2002), Descamps et al. (2009) showed that this pattern was actually reversed when there was heightened exposure to avian cholera . This result suggests that female eiders may only pay the fitness costs of high reproductive effort under unfavorable conditions. "
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