The effect of diet quality on physiological and life-history traits in the harvestman Pachylus paessleri

• Published in: Journal of insect physiology Vol. 53; no. 2; pp. 132 - 138
• Main Authors: Naya, Daniel E., Lardies, Marco A., Bozinovic, Francisco
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2007
• Subjects: Analysis of Variance; Animals; Arachnida - physiology; Basal Metabolism; body condition; Body Constitution - drug effects; Body Weight - drug effects; body weight changes; Carbon Dioxide - metabolism; Chile; Dietary Carbohydrates - pharmacology; Dietary Proteins - pharmacology; energy expenditure; Energy Metabolism - drug effects; experimental diets; Fecundity; Female; Fertility - drug effects; Food quality; high carbohydrate diet; high protein diet; Metabolic rate; metabolism; mortality; nutritional adequacy; Opiliones; Phenotypic plasticity; reproduction; Solanum tuberosum; Somatic condition; standard metabolic rate; Chile; Metabolic rate; Phenotypic plasticity; Food quality; Somatic condition; Fecundity
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2006.11.004

The balance between energy acquisition and expenditure is critical to the survival and reproductive success of animals. Here we investigate the long-term effects of diet quality on physiological and life-history flexibility in the harvestman, Pachylus paessleri. We used cow meal as a protein-rich diet and potatoes as a carbohydrate-rich diet in order to reproduce two extreme conditions regarding food quality in harvestmen natural habitat. As proxy variables of the energy expenditure process, we quantified standard metabolic rate (maintenance), changes in body mass (somatic condition), and fecundity (reproduction). We found that animals consuming the protein-rich diet were able to increase both their body condition and fecundity. However, the increment in these two life-history traits was correlated with higher maintenance costs. In contrast, the carbohydrate-rich diet did not provide enough specific nutrients for reproductive events, although it may have allowed animals to survive for a long time. Thus, according to the quality of the diet available in the environment, harvestman females can adopt different life-history strategies correlated with phenotypic adjustments at anatomical and physiological levels. In the Mediterranean region, spatial and temporal changes in food quality are typical, so greater phenotypic flexibility is expected to cope with this kind of environmental variation.