Temperature-size rule is mediated by thermal plasticity of critical size in Drosophila melanogaster

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 280; no. 1760; p. 20130174
• Main Authors: Ghosh, Shampa M., Testa, Nicholas D., Shingleton, Alexander W.
• Format: Journal Article
• Language: English
• Published: England The Royal Society 07.06.2013
• Subjects: Adaptation, Biological - physiology; Analysis of Variance; Animals; Body Size - physiology; Body Weights and Measures; Critical Size; Drosophila; Drosophila melanogaster; Drosophila melanogaster - growth & development; Growth Duration; Growth Rate; Logistic Models; Manduca - growth & development; Manduca sexta; Models, Biological; Species Specificity; Temperature; Temperature-Size Rule; Thermal Plasticity
• ISSN: 0962-8452; 1471-2945; 1471-2954
• DOI: 10.1098/rspb.2013.0174

Most ectotherms show an inverse relationship between developmental temperature and body size, a phenomenon known as the temperature-size rule (TSR). Several competing hypotheses have been proposed to explain its occurrence. According to one set of views, the TSR results from inevitable biophysical effects of temperature on the rates of growth and differentiation, whereas other views suggest the TSR is an adaptation that can be achieved by a diversity of mechanisms in different taxa. Our data reveal that the fruitfly, Drosophila melanogaster, obeys the TSR using a novel mechanism: reduction in critical size at higher temperatures. In holometabolous insects, attainment of critical size initiates the hormonal cascade that terminates growth, and hence, Drosophila larvae appear to instigate the signal to stop growth at a smaller size at higher temperatures. This is in contrast to findings from another holometabolous insect, Manduca sexta, in which the TSR results from the effect of temperature on the rate and duration of growth. This contrast suggests that there is no single mechanism that accounts for the TSR. Instead, the TSR appears to be an adaptation that is achieved at a proximate level through different mechanisms in different taxa.