Islands or Artic: Scaling of Gromphadorhina portentosa and Blaptica dubia species to support Bergmann’s rule

Jared Warburton, Sarah Teeman, Aubrey Sumner, Raymond Harrison Trumble, Andrea Gensky


Both endotherms and ectotherms use thermoregulation to maintain homeostasis using internal conditions or external maneuvers, respectively. Scaling of species occurs through Bergmann’s rule, where species that are located further away from the equator are generally larger. We predict that the Gromphadorhina portentosa, or Madagascar hissing cockroaches (MHC) will display a higher metabolic rate than the Blaptica dubia, or Dubia roaches (DR), as the ambient temperature increases, because they have a larger body mass. To test this we will survey three roaches of each species under cold, normal room, and warm temperatures under three-minute trials. After further assessment, the results indicated that our hypothesis was supported as under every condition, that MHC had a higher metabolic rate per roach. This experiment and related studies tend to display similar trends among ectotherms, further supporting Bergmann's rule.

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