Submitted to: Journal of Orthoptera Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2008
Publication Date: 3/2/2009
Citation: Branson, D.H. 2009. Influence of Individual Body Size on Reproductive Traits in Melanopline Grasshoppers (Orthoptera: Acrididae). Journal of Orthoptera Research. 17(2):259-263. Interpretive Summary: Numerous biotic and environmental factors can influence body size and reproduction in grasshoppers. It is important to determine the relative influence biotic factors and body size have on fecundity, to aid in our ability to predict grasshopper population dynamics and outbreaks. In addition, individual variation in reproduction allocation has important implications for understanding life-history evolution. As food resource availability can explain much of the variation in reproduction, the effects of food availability could conceal the influence of body size on reproduction. However, relationships between body size and reproduction traits were apparent in three experiments manipulating food availability. As correlations between body size and reproduction are inconsistent, both in these experiments and in previously published work, additional research is needed to better understand how body size affects reproduction and if relationships between body size and reproductive traits change with food availability.
Technical Abstract: Body size is a fundamental trait of an organism, affecting most aspects of its performance, including reproduction. Numerous biotic and environmental factors can influence individual body size and reproduction in grasshoppers. Using data from four experiments, I examined intraspecific relationships between reproductive traits and either grasshopper body size or weight in Melanoplinae grasshoppers. Significant positive correlations between body size and reproductive traits occurred in three of four experiments for both Melanoplus sanguinipes (Fabricius) and Phoetaliotes nebrascensis (Thomas). In addition, individual femur length variation was significant as a covariate in explaining additional variation beyond the effects of the manipulative treatments in at least one reproductive trait in three experiments. As correlations between reproductive traits and body size were not evident in one experiment, an unresolved question is if relationships between body size and reproductive traits change with food availability. Food limitation would likely have a larger proportional effect on lifetime reproduction than body size, but additional research is needed to determine the relative roles biotic factors and individual body size play in determining reproductive allocation in grasshoppers.