Speeding Up Microevolution: The Effects of Increasing Temperature on Selection and Genetic Variance in a Wild Bird Population

The authors show that environmental variation may lead to a positive association between the annual strength of selection and expression of genetic variance in a wild bird population, which can speed up microevolution and have important consequences for how fast natural populations adapt to environmental changes

Variation in the adult body mass of Wilson's storm petrels Oceanites oceanicus during breeding

Quillfeldt P, Masello J, Lubjuhn T. Variation in the adult body mass of Wilson’s storm petrels Oceanites oceanicus during breeding. Polar Biology. 2006;29(5):372-378.Mass loss of breeding birds might be due to the physiological stress of breeding or it could be an adaptation to lower the costs of flight to the feeding areas. We examined the natural variation in the adult body mass of Wilson’s storm petrels Oceanites oceanicus on King George Island, South Shetland Islands over four breeding seasons. During two seasons, the prey abundance was high, while it was poor during the other two seasons. Only breeding birds were sampled; the fluctuations in mass were similar among males and females. During incubation, the mass of the adults was high in good seasons and low in poor seasons. Thus, body mass during incubation was determined by energetic constraints. However, during chick feeding, adults lost mass in the good seasons but gained mass in the poor seasons, suggesting that mass loss during chick rearing is not primarily caused by stress, but is regulated adaptively. Adults in poor conditions may buffer against unpredictable food supply by increasing their own body mass, even at the expense of the chick. Reduced body condition at the beginning of the breeding season was associated with reduced egg volumes and late laying, suggesting that the initial body condition influenced the level of investment in the current breeding attempt

Leucocytes in adult burrowing parrots Cyanoliseus patagonus in the wild: Variation between contrasting breeding seasons, gender, and individual condition

International audienceWild birds exposed to stressors may modulate their investment in immunity. We studied the leucocytes of breeding burrowing parrots () in Patagonia during five breeding seasons, during which global climate events such as a strong La Niña and a weak El Niño occurred. We observed strong inter-annual variation in the ratio of heterophils to lymphocytes (/), with higher / during the adverse conditions of La Niña compared with the favourable conditions of El Niño for the studied region. Nevertheless, highest / were found in the breeding season following a La Niña event; this is probably explained by a combination of long-term detrimental effects of climatic conditions and other, e.g. biotic, stressors. Males had higher / than females, and / ratios were negatively related to individual body condition

Do leucocytes reflect condition in nestling burrowing parrots Cyanoliseus patagonus in the wild?

Masello J, Choconi RG, Helmer M, Kremberg T, Lubjuhn T, Quillfeldt P. Do leucocytes reflect condition in nestling burrowing parrots Cyanoliseus patagonus in the wild? Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology. 2009;152(2):176-181.The different leucocyte types are an important part of the immune system. Thus, they have been used in ecological studies to assess immune function and physiological stress in wild birds. It is generally assumed that increased stress and decreased condition are associated with an increase in the ratio of heterophils to lymphocytes, the H/L ratio. We studied leucocyte profiles in relation to body condition in nestling Burrowing Parrots (Cyanoliseus patagonus) in North-eastern Patagonia, Argentina. As in other wild parrots, heterophils were the most numerous leucocyte type, suggesting strong investment into innate immunity. Leucocyte profiles did not change with the age, while nestlings in better body condition increased the number of heterophils. Because the number of lymphocytes was independent of body condition, as a result we observed a positive correlation between body condition and the H/L ratio. The total number of leucocytes relative to erythrocytes increased in nestlings in better body condition, indicating a larger overall investment into immune function in well-nourished nestlings. The observed heterophilic profiles of nestling Burrowing Parrots together with the positive relationship between H/L ratio and body condition may indicate a favoured investment in a robust innate immunity that reduces the risk of infection taking hold in these long-lived birds