FROM MOLECULES TO MATING SUCCESS - INTEGRATIVE BIOLOGY OF MUSCLE MATURATION IN A DRAGONFLY

Dragonflies begin adult life as comparatively weak fliers, then mature to become one of nature's ultimate Eying machines, This ontogenetic t ransition provides an opportunity to investigate the relationship betw een life history, phenotypic plasticity, and changing ecological deman ds on organismal performance. Here we present an overview of a wide-ra nging study of dragonfly muscle maturation that reveals i) ecological changes in the need for efficient versus high-performance flight, ii) organism-level changes in performance, thermal physiology, locomotor m echanics, and energy efficiency, iii) tissue-level changes in muscle u ltrastructure and sensitivity to activation by calcium, and iv) molecu lar-level changes in the isoform composition of a calcium regulatory p rotein in flight muscle (troponin-T), We discuss how these phenomena m ay be causally related, and thereby begin to show Linkages across many levels of biological organization. In particular, we suggest that alt ernative splicing of troponin-T mRNA is an important component of the ''gearing'' of muscle contractile function for developmental changes i n wingbeat frequency and ecological demands on flight performance. Age -variable gearing of muscle function allows energetically economical f light during early adult growth, whereas power output is maximized at maturity when aerial competition determines success during territorial ity and mating.