Trade-off acquisition and allocation in Gryllus firmus: a test of the Y model


Elizabeth King, Department of Ecology & Evolution, University of California, Irvine, CA 92697-2525, USA.
Tel.: (949) 824 5994; fax: (949) 824 2181; e-mail:


Many models of life history evolution assume trade-offs between major life history traits; however, these trade-offs are often not found. The Y model predicts that variation in acquisition can mask underlying allocation trade-offs and is a major hypothesis explaining why negative relationships are not always found between traits that are predicted to trade-off with one another. Despite this model’s influence on the field of life history evolution, it has rarely been properly tested. We use a model system, the wing dimorphic cricket, Gryllus firmus as a case study to test the assumptions and predictions of the Y model. By experimentally altering the acquisition regime and by estimating energy acquisition and energy allocation directly in this species, we are able to explicitly test this important model. Overall, we find strong support for the predictions of the Y model.