Biological Journal of the Linnean Society, 2007, 90, 293–302. With 3 figures © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90, 293–302 293 Blackwell Publishing LtdOxford, UKBIJBiological Journal of the Linnean Society0024-4066(c) 2007 The Linnean Society of London? 2007 90? 293302 Original Article LIFE-HISTORY STRATEGIES IN INSECTS M. A. JERVIS ET AL . *Corresponding author. jervis@cf.ac.uk Egg maturation strategy and survival trade-offs in holometabolous insects: a comparative approach MARK A. JERVIS 1 *, CAROL L. BOGGS 2 and PETER N. FERNS 1 1 Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3TL, Wales, UK 2 Center for Conservation Biology, Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA Received 21 October 2005; accepted for publication 1 March 2006 One of the key predictions of general life-history theory is that reproduction incurs a survival cost. Although there is a convincing body of evidence to support this prediction at the intraspecific level in insects, evidence at the inter- specific level is relatively scarce, as is the case for other animals. By employing two methods of phylogenetically con- trolled analysis, we demonstrate the existence of a negative correlation between life-span and early life investment in reproduction, across a wide diversity of Lepidoptera. The measure of initial reproductive effort used was the ’ovig- eny index’, defined as the proportion of the lifetime potential egg complement that is mature (ready to lay) upon female emergence. We present a graphical model for holometabolous insects, illustrating the trade-offs that are hypothesized to occur among capital resources (soma vs non-soma and initial eggs vs storage) in relation to variation in ovigeny index. These trade-offs, for which there is some empirical support, are postulated to underlie the life-span/ ovigeny index relationship observed in the Lepidoptera and also in other insect orders. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90, 293–302. ADDITIONAL KEYWORDS: cost of reproduction – Hymenoptera – Lepidoptera – reproductive investment – resource allocation – Trichoptera. INTRODUCTION EGG MATURATION STRATEGY AND ITS ASSOCIATED TRADE-OFFS IN INSECTS A key prediction of general life-history theory is that reproduction incurs a survival cost (Roff, 2002). In particular, various allocation models predict a trade- off between life-span and early life investment in reproduction (Gadgil & Bossert, 1970; Van Noordwijk & de Jong, 1986; Zera & Harshman, 2001; Novoseltsev et al., 2002; Roff, 2002). For insects, there is a signifi- cant body of empirical evidence to support this predic- tion at the intraspecific level (Partridge & Farquhar, 1981; Luckinbill et al., 1984; Rose, 1984; Ernsting & Isaaks, 1991; Kaitala, 1991; Kopelman & Chabora, 1992; Tatar, Carey & Vaupel, 1993; Valicente & O’Neill, 1995; Ellers & van Alphen, 1997; Partridge, Prowse & Pignatelli, 1999; Dixon, 2000; and see ref- erences above), but data relating to the interspecific level are relatively scarce (Kaitala, 1991; Dixon, 2000; Jervis et al., 2001; Pexton & Mayhew, 2002; Jervis, Ferns & Heimpel, 2003). Indeed, for animals as a whole, there are relatively few documented examples of any kind of cross-species reproduction/survival trade-off (Read & Harvey, 1989; Stearns, 1992; Roff, 2002; Jervis et al., 2003). This most likely reflects dif- ferences in the intensity of research effort at the two taxonomic levels, rather than the existence of any con- straint upon the presence of such a trade-off at the interspecific level. The question thus remains as to whether a repro- duction/survival trade-off occurs more generally. Focusing on holometabolous insects, we ask whether, given the known interspecific early life reproduction/ life-span trade-off in the order Hymenoptera (Jervis et al., 2001; Pexton & Mayhew, 2002), such a relation- ship also exists in another major order, the Lepi- doptera. The scattered literature on egg maturation in Lepidoptera (Eidmann, 1931; Labine, 1968; Janzen,