Meeting Abstract
Invasive species are a major driver of biodiversity loss. Some hypotheses suggest successful invaders would demonstrate different stress and immune response profiles than native species. The higher dispersal rate common in invasive species are associated with elevated energetic demands and glucocorticoids levels (GCs). Additionally, it is hypothesized that invasive species should utilize one type of immune response (innate or adaptive) over the other based on energetic cost of the response, potentially reducing pathogen load. We explored the relationship among GC, immune responsiveness, and energetic cost in cane toads (Rhinella marina), an invasive species in Florida. Toads (N=14) were acclimated to captivity for 3 weeks at which time we measured their metabolic rate (MR) and took a blood sample to determine their bacterial killing ability (BKA, an innate immune response), corticosterone levels (CORT) and antibody titers (IGG). Toads were then injected with 20% SRBC or saline solution. One-week post injection, toads’ MR was again measured. They were re-bled and re-challenged with 20% SRBC or saline injections. We predicted SRBC challenged toads would exhibit higher MR, CORT and IGG, while showing lower BKA. We found a significant increase in IGG in SRBC vs. saline injected toads 7 days after injection (F1,11=8.513, p=0.014). The second SRBC challenge did not significantly increase IGG over levels observed after the first challenge in SRBC toads (p=1.000). There was no difference between saline vs. SRBC in MR (F1,12=1.149, p=0.305), but MR increased in SRBC challenged toads after 7 days compared to before injection (p=0.028). There were no significant differences in CORT (F1,11=0.031, p=0.863) or BKA (F1,11=1.269, p=0.284) between SRBC and saline controls.
