18-6 Monday, Jan. 4 11:30 Invasion of a novel predator reverses latitudinal gradients of multiple traits in a native lizard THAWLEY, C.J.*; GOLDY-BROWN, M.; MCCORMICK, G.L.; GRAHAM, S.P.; LANGKILDE, T.; Penn State University; Penn State University; Penn State University; Sul Ross State University; Penn State University firstname.lastname@example.org http://langkildelab.weebly.com/chris-thawley.html
Ecologists have long been fascinated by latitudinal gradients and the selective mechanisms that drive their formation and maintenance. Environmental change, including climate change and invasive species, can alter selective pressures across large portions of species’ ranges. Resulting changes in species’ traits are generally assumed to be adaptive, but could alter existing latitudinal patterns, potentially imposing costs. We examined how latitudinal patterns of morphology, behavior and physiology in the eastern fence lizard, Sceloporus undulatus, are affected by invasion of the red imported fire ant, Solenopsis invicta, which occupies the southern half of this species’ range. When moving from north to south along a latitudinal gradient outside of the fire ant’s range, lizard populations become less responsive to ants, have relatively shorter legs, and have lower stress responses. However, the direction of these gradients is reversed in the presence of fire ants; in more southern areas invaded by fire ants, lizard populations are more responsive to ants and have longer legs, adaptations to surviving attack by fire ants, and have higher stress responses, likely a response to frequent attack by these predatory ants. These changes represent shifts away from trait values that evolved under natural conditions, suggesting that these adaptations may incur costs.