Evol Ecol Res 6: 415-431 (2004)     Full PDF if your library subscribes.

Genetic, environmental and maternal effects on magpie nestling-fitness traits under different nutritional conditions: a new experimental approach

Liesbeth De Neve,1* Juan José Soler,2 Tomás Pérez-Contreras2 and Manuel Soler1

1Departamento de Biología Animal y Ecología, Facultad de Ciencias, Universidad de Granada, 18071 Granada and  2Estacíon Experimental de Zonas Áridas, CSIC, c/ General Segura 1, 04001 Almeira, Spain

Address all correspondence to Liesbeth De Neve, Museo Nacional de Ciencias Naturales, CSIC, c/ José Gutiérrez Abascal 2, 28006 Madrid, Spain.
e-mail: deneve@mncn.csic.es

ABSTRACT

Rearing full siblings under different environmental conditions allows partitioning of the total phenotypic variance of a trait into its genetic and environmental components. This, in natural bird populations, is usually achieved by cross-fostering experimental designs. We estimated genetic and environmental components of nestling-fitness traits using an alternative experimental approach in a magpie (Pica pica) population. Two broods of full siblings were reared under contrasting environmental conditions of first and replacement clutches. With this approach, potential maternal effects related to differences in clutch size and egg size could also be partially evaluated. In addition, the nutritional condition of half of the nestlings within each nest was manipulated by providing a calorie-rich paste enriched with micronutrients. Our results are only indicative because of very low sample sizes. In food-supplemented nestlings, the heritability estimates of tarsus length, body mass and T-cell-mediated immune response tended to be higher compared with control nestlings. No causal conclusions could be drawn for changes in heritability estimates of body mass and T-cell-mediated immune response; for tarsus length, the results suggest a lower potential to adapt to poor nutritional conditions. Furthermore, we found some indication that maternal effects related to clutch/egg size inflated causal estimates of phenotypic variance in tarsus length.

Keywords: body mass, food supplementation, immune response, magpie, maternal effects, Pica pica, quantitative genetics, tarsus length.

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