Meeting Abstract
Invasive species can harm native fauna through competition and predation, and toxic invaders can poison native predators. Cane toads, introduced to several locations around the world, have been reported with larger parotoid (poison) glands near the invading front in Australia, indicating higher risk to naïve predators. To assess relative toxicity of Florida cane toads in terms of gland sizes and likelihood of secreting poison, approximately 20 toads per population were captured and placed into plastic bags from 9 Florida populations. Following one hour of capture, toads were removed from the bags and mass, sex, and snout-vent-length (SVL) were recorded. Toads were placed next to a ruler and images were obtained to measure gland sizes, with images also showing if a toad was secreting poison following this handling period. Measurements of total length, width, and area of glands were performed using Image J software. An ANCOVA using the first component of a principal component analysis (“small gland size”) of Log-transformed gland length, width, and area, was used to explain morphological differences among Florida toads. Gland sizes increased with increasing body mass (p = 0.019), although they were not significantly affected by latitude. Using a generalized linear model to assess likelihood of poison secretion, toads were twice as likely to secrete following capture and handling with every degree of increasing latitude (p = 0.038). Although gland sizes of Florida toads didn’t significantly change with latitude, the likelihood of toads secreting poison as distance from the introduction point increases in Florida is similar to Australian cane toads, and may indicate relative toxicity increases with increased dispersal.
