Ecology, 90(8), 2009, pp. 2202–2212 Ó 2009 by the Ecological Society of America Reproductive timing and patterns of development for the damselfly Coenagrion puella in the field CHRIS D. LOWE,IAN F. HARVEY,PHILLIP C. WATTS, AND DAVID J. THOMPSON 1 School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB United Kingdom Abstract. By a combination of detailed behavioral observations and molecular genetic approaches we have assessed development time, timing of first maturity, and the extent of genetic structure through the flying season in a wild population of the damselfly Coenagrion puella in England. This work provides the first estimate of development time (egg to mature adult) in the field based on individual damselflies. Development time was significantly longer for females than males. In contrast to reported laboratory studies, there was no difference in development times between different female color morphs. Development time ranged between 347 and 396 days and was negatively correlated with egg-laying date. As a result eggs laid early in one season reach adult maturity relatively late in the next; concurrently individuals developing from eggs laid late mature relatively early. We speculate that this pattern of development is a direct physiological response to seasonal environmental variation and results in reproductive synchrony within a population. Size, specifically hind wing length, declined with development time in males, but not in females. In one of the two years of the study there was evidence for weak clustering of related individuals during the reproductive season. This appeared to be the result of developmental synchronization within families: variance in timing of maturation was smaller in full-sib families than in half-sib families or randomly assigned unrelated groups. Key words: Coenagrion puella; complex life cycle; damselfly; development time; fitness; life history plasticity; parentage analysis; temporal genetic structure; time constraints. INTRODUCTION Ever since Moran’s (1994) review, increasing atten- tion has been focused on animals with complex life cycles. Animals that come into this category were defined by Moran as those whose lives contain different phases that ‘‘exhibit contrasting morphological, physio- logical, behavioral, or ecological attributes.’’ The literature on complex life cycles has focused in two areas: on the ecological, in which there has been an emphasis on how different stages evolve to gather resources while other stages disperse and reproduce; and the developmental, which has been concerned with how evolution in one phase effects development in another (Moran 1994). Although most subsequent ecological work has been carried out with holometab- olous insects, such complex life cycles are not restricted to insects but are found in many groups such as amphibians, crustaceans, and mollusks. The life history consequences of such life cycles for odonates were first explored by Johansson and Rowe (1999), building on theoretical work on life history constraints by Roff (1980, 1992) and Rowe and Ludwig (1991). Johansson and Rowe (1999) demonstrated that time-constrained larvae accelerated development rate and matured at an earlier age and at a smaller size. The body of work stimulated by Johansson and Rowe’s paper has indicated that under a time constraint organisms increased their development rate (e.g., Jo- hansson et al. 2001, De Block and Stoks 2003), but results on body size were equivocal, contrary to the predictions of optimality models (e.g., Abrams et al. 1996). Detailed experimental work by De Block and Stoks (2005) indicated that larval constraints did not necessarily carry over into adult fitness through size and timing of transition. Rolff et al. (2004) demonstrated that time constraints decoupled the relationship between age and size at maturity in a damselfly, particularly in relation to some physiological traits, most notably a component of immunity. They suggested that the predictive value of traits such as age and size at maturity might be restricted. Strobbe and Stoks (2004) pointed out that genetic constraints might have contributed toward different responses to a time constraint for size and mass. While the mechanisms by which developmental constraints act and the responses of developmental parameters to time cues have remained unclear, it is apparent that development has important consequences for individual survival and fitness by determining the timing of life history transitions (e.g., maturity and reproduction; Plaistow and Siva-Jothy 1999). Maturity Manuscript received 25 September 2008; revised 25 November 2008; accepted 5 December 2008. Corresponding Editor: S. J. Simpson. 1 Corresponding author. E-mail: d.j.thompson@liv.ac.uk 2202