GOOSEPHYSIOL · Resilience to global change in long-lived species: physiological comparisons between Arctic and temperate-breeding barnacle geese

Resilience to global change in long-lived species: physiological comparisons between Arctic and temperate-breeding barnacle geese

Our project investigates behavioural and physiological constraints of adaptation in animals to rapidly changing environments. Particularly the Arctic is now experiencing some of the most rapid and severe climate changes on earth. Recent studies mainly emphasise the inability of species to adapt to such changes. In this project, we have approached this problem by studying a traditionally migratory Arctic-breeding species, the barnacle goose, that instead has been very successful in spreading into new, temperate, environments. Predictions from life-history theory implies a relatively higher 'pace-of-life' (increased growth and metabolic rates) but reduced immune defence under climate-harsh and germ-poor conditions in the Arctic as compared to conditions in more benign but germ-rich temperate regions. Furthermore, already the developing embryo experiences a risk of disease. To shield their progeny from microbial attacks, mothers can transfer protective proteins into their eggs, and it is predicted that immune factors deposited in eggs differ depending on specific nest Environment and the risk of contracting disease early in life. To test these predictions, we compare arctic- and temperate breeding barnacle goose populations for parasite loads, growth and metabolic rates, immune function with focus on innate immunity, energetic costs involved in mounting an immune response, and immune factors in eggs. We found significantly higher loads of intestinal parasites in temperate-breeding (Dutch) geese as compared to arctic-breeding (Russian) geese in terms of coccidian oocyst and helminth egg counts (G. Eichhorn, talk at Nordic Oikos conference 2014). In contrast, ecto-parasite diversity, prevalence and abundance were similar in arctic and temperate populations (L. Gijsen, MSc thesis 2014, Lund University). Ecto-parasites complete their whole life cycle on the host and, apparently, depend less on the host’s environment. Screening for haemosporidian (blood) parasites by PCR-based molecular tools is currently in process and will nicely complement the picture on parasite patterns, since blood parasites depend additionally on vectors (insects) in the environment. Goslings in Arctic Russia showed higher growth rates, confirming a supposed benefit of breeding at higher latitudes. Among our objectives is also to test if higher growth rates are supported by higher metabolic rates and, moreover, to investigate possible trade-offs between immune defence and energy metabolism in young geese raised in both biota. Thus far, complications in Russia prevented us from measurements of metabolic rates in the Arctic population for comparison. However, we will continue pursuing this objective in summer 2014. Plasma samples gathered from Dutch, Swedish and Russian goose populations were used in two immune assays: 1) haemolysis-haemagglutination assay characterising natural antibody-mediated complement activation; 2) haptoglobin assay as a measure of acute phase protein concentration. Post-laboratory and data analysis is in process. We measured albumen concentrations of lysozyme and ovotransferrin (two supposed immune factors, albeit of unspecific defence) in geese eggs sampled from Dutch, Swedish, Finnish and Russian breeding sites. Lysozyme concentration was highest in eggs from the Dutch (southernmost) site and equally lower in all other sites, a pattern partly in line with presumed higher infection risk in southern breeding sites. In contrast and opposite to our expectation, ovotransferrin concentration was lowest in the Dutch site, intermediate in Swedish and Finnish sites, and highest in the Russian site (H. Schepp, MSc thesis 2014, Wageningen University). Thus, our results reveal a more complicated picture of geographically nest-site dependent disease risk for the developing embryo and/or a more intricate role of lysozyme and ovotransferrin in mediating adaptation to local diseases risk. It will be interesting to complement these results with an analysis of more specific immune factors like, for instance, immunoglobulins transferred by mothers into egg yolk. The final combined results of these various project objectives will yield novel insights into the adjustments to the physiological phenotype needed to cope with rapidly changing environments, and the adaptive value in the transition from migratory to non-migratory behaviour.

Data: CORDIS, © European Union