Elucidating the history of anuran invasions: life history characteristics associated with range expansion in Florida

<p>Invasive species pose serious ecological and economic threats to native biological systems. The temporal dynamics of invasions vary tremendously and are often difficult to characterize but can provide key insights into patterns of establishment and spread of introduced species. Herein, we reconstructed the invasion history of two amphibians that are of ecological concern in Florida, the cane toad (<em>Rhinella marina</em>) and Cuban treefrog (<em>Osteopilus septentrionalis</em>). We analyzed publicly available datasets using deterministic spatial interpolation to quantify the range expansion of both species within Florida since their establishment. We found that both species were restricted to small geographic regions of Florida until about 1990, when they increased their rate of spread due at least in part to multiple transplantation events. Since 1990, both species have undergone sharp range increases that may be due to increased recruitment and landscape disturbances caused by Hurricane Andrew in 1992. Presently, the expansion rate of the cane toad shows initial signs of slowing while the Cuban treefrog continues to grow at an exponential rate of increase. Our results highlight the commonalities and differences in range expansion between anuran species with disparate natural history strategies. Short generation time and high fecundity, in combination with disturbances caused by hurricanes, appear to have fueled both species’ invasions. By comparing invasion histories across species, we can begin to understand the drivers that may influence anuran invasions, including historical events, climate, habitat availability and life history characteristics.</p>