Non-native species introductions are becoming increasingly common, but we know remarkable little about the long-term consequences of the novel pressures invaders impose on the native species they encounter.  In addition to being critical to the effective management of invaders, this information provides valuable insight into processes that structure communities and permit species coexistence.  Our research aims to understand how interactions between invaders and native species change across invasion time, and how these changes alter the consequences of invasion for native communities. 

Red imported fire ants (Solenopsis invicta) attacking a grasshopper

a) Ecological impacts of invasion


Attacks by the red imported fire ant, a globally important invader, on native fence lizards are common and can be lethal.  We have found that fence lizards have adapted to this novel threat, employing behavioral strategies that improve their chances of surviving aggressive encounters, within 70 years of invasion.  In addition to posing a novel predation threat, fire ants also represent dangerous prey, allowing us to test adaptation to multiple forms of novel threat.  We are investigating whether lizards can learn to avoid fire ants, and how their introduction affects the lizards diet and/or foraging strategies.  We plan to use these data, along with those on the life history of lizards at these sites, to model the population-level impacts of this invasion.


Relevant publications:


Langkilde, T. 2010. Repeated exposure and handling effects on the escape response of fence lizards to encounters with invasive fire ants. Animal Behaviour  79: 291-298


Langkilde T. 2009. Holding ground in the face of invasion: native fence lizards (Sceloporus undulatus) do not alter their habitat use in response to introduced fire ants (Solenopsis invicta). Canadian Journal of Zoology 87: 626-635


Langkilde T. 2009. Invasive fire ants alter behavior and morphology of native lizards. Ecology 90: 208-217


Langkilde T., Smith V., Phillips S., Barrott E. and Shine R. 2003. Ornamental plant traps lizard.  Herpetofauna 32:131



b) Invasive iguanas and nutrient flow


Lindsey Swierk, a graduate student in the lab, is investigating the community-level impact of invasive iguanas.  Iguanas are voracious herbivores that consume large amounts of leaf material, even completely defoliating trees, and input large amounts of fecal material into invaded systems.  This change in nutrient flow likely has important, but unknown, impacts on the local community. See Lindsey’s page for more details.


Relevant publications:


Swierk, L.N. and T. Langkilde. 2009. Micronutrient input into a mangrove ecosystem in Jobos Bay, Puerto Rico, by the exotic green iguana Iguana iguana. Current Zoology 55: 435-438





Consequences of Invasion









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