Covariation among organismal traits is nearly universal, occurring both within and among species (static and evolutionary allometry, respectively). If conserved developmental processes produce similarity in static and evolutionary allometry, then when species differ in development, it should be expressed in discordance between allometries. Here, we investigate whether rapidly evolving developmental processes result in discordant static and evolutionary allometries attributable to trade-offs in resource acquisition, allocation, or growth across 30 species of aquatic beetles. The highly divergent sperm phenotypes of these beetles might be an important contributor to allometric evolution of testis and accessory gland mass through altered requirements for the production of sperm and seminal fluids. We documented extensive discordance between static and evolutionary allometries, indicating that allometric relationships are flexibly modified over short time periods but subject to constraint over longer time spans. Among species, sperm phenotype did not influence relative investment in accessory glands but was weakly associated with investment in testes. Furthermore, except when sperm were long and simple, sperm phenotype was not associated with species-specific modification of the allometry of testis/accessory gland mass and body size. Our results demonstrate the utility of allometric discordance to infer species differences in the provisioning and growth of concurrently developing traits.

Consensus_treeA nexus file containing the majority rule consensus tree produced from 40,000 post burn-in trees.MrBayes_inputA nexus file containing sequence alignments and MrBayes commands. Taxa names correspond to the abbreviations listed in Table2.PATHd8_inputInput file for the program PATHd8. Contains details of the fossil calibration.TableS1Tab delineated file contains raw data (testis, paragonial and body mass) used to calculate inter- and intraspecific allometric relationships.Table S2Tab delineated file contains insect family names, species names, presence and type of conjugation, sample sizes, trait means and standard errors. Missing data is coded with na. For a few species, only minimum sperm length were available (determined from sperm bundles or potentially broken sperm) and is indicated with *.TableS2Table S3Tab delineated file contains species names and accession numbers for mitochondrial DNA sequences. Also includes abbreviated names used in Nexus file.TableS3Ultrametric_treeA nexus file containing a fossil calibrated tree (see article for details) with polytomies randomly resolved in Mesquite.Read MeContains descriptions of other files in this data set.