Allometric and non-allometric consequences of inbreeding on Drosophila melanogaster wings VINCENZO TROTTA 1 *, SANDRO CAVICCHI 1 , DANIELA GUERRA 1 , DITTE H. ANDERSEN 2 , GREGORY A. BABBITT 3 , TORSTEN N. KRISTENSEN 2,4 , KAMILLA S. PEDERSEN 2,4 , VOLKER LOESCHCKE 2 and CINO PERTOLDI 2,5 1 Alma Mater Studiorum, Università di Bologna, Dipartimento di Biologia Evoluzionistica Sperimentale, Via Selmi 3, 40126, Bologna, Italy 2 Department of Biological Sciences, Ecology and Genetics, Aarhus University, Ny Munkegade, Building 1540, DK-8000 Aarhus C, Denmark 3 Center for Evolutionary Functional Genomics, The Biodesign Institute and School of Life Sciences, Arizona State University, PO Box 875301 Tempe, AZ 85287-5301, USA 4 Department of Genetics and Biotechnology, Aarhus University, Blichers Allé 20, DK-8830, Denmark 5 Mammal Research Institute, Polish Academy of Sciences, Waszkiewicza 1c, 17-230 Bialowiez ˙a, Poland Received 15 June 2010; revised 27 September 2010; accepted for publication 27 September 2010 Inbreeding is expected to increase the variability in size and shape within populations. The distinct effects of inbreeding on size and shape suggest that they are governed by different developmental pathways. One unresolved question is whether the non-allometric shape component is partially unconstrained developmentally and therefore whether shape is evolvable. In the present study, we utilized a mass outbred population of Drosophila melanogaster maintained at standard laboratory conditions. Eight lines with equivalent expected levels of inbreeding (F ª 0.67) were obtained by restricting the size of each population to two pairs for nine generations. Nine landmarks were measured on Drosophila wings of the inbreed lines and compared with those of the mass population. Wing landmarks comprise an excellent model system for studying evolution of size and shape. Landmark measurements were analyzed with a Procrustes generalized least squares procedure. To visualize global shape changes among samples, we reconstructed the mean shape and the shape changes related to both the allometric and non-allometric components. An increased variability in the non-allometric shape component was found with inbreeding. This indicated that shape was not entirely developmentally constrained, and therefore that shape appears to be evolvable. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 626–634. ADDITIONAL KEYWORDS: allometry – wing shape. INTRODUCTION Studies in different species of the genus Drosophila have revealed that genetic variation for body size and shape occurs in natural populations (Stalker & Carson, 1947; Prevosti, 1955; David, Bocquet & De Scheemaeker-Louis, 1977; James, Azevedo & Par- tridge, 1997; Pezzoli et al., 1997; Huey et al., 2000; Gilchrist, Huey & Serra, 2001; Calboli, Gilchrist & Partridge, 2003; Gibert et al., 2004; Trotta et al., 2006). In Drosophila, some quantitative traits provide more or less the same information because they are positively correlated (David et al., 2005). For example, wing area is positively correlated with body size as a whole (Robertson & Reeve, 1952; Robertson, 1959; Misra & Reeve, 1964; Wilkinson, Fowler & Partridge, 1990; Partridge et al., 1994, 1999; Huey et al., 2000; Calboli et al., 2003; David et al., 2005, 2006). The final size and shape of the Drosophila wing is the result of tight coordination among cell *Corresponding author. E-mail: v.trotta@unibo.it Biological Journal of the Linnean Society, 2011, 102, 626–634. With 5 figures © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 626–634 626 Downloaded from https://academic.oup.com/biolinnean/article/102/3/626/2450571 by guest on 03 February 2023