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Burmese Python Invasion Risk: Bioclimatic and Physiological Models Burmese Python, Python molurus bivittatus ● Generalist snakes native to Southern Asia ● Established in Southern Florida via pet trade ● Great concern in the Everglades ○ 31 species at risk due to python predation Species Distribution Two Models of Invasion Risk Bioclimatic Envelope Model- uses empirical data about species distribution to inform model. Physiological Model - uses empirical data about a species’ physiological tolerance to inform model. Bioclimatic Models: Individual Suitability Maps * Annual Mean Temp. Range: 19.6 - 24.5 C Combined Quarterly Rainfall Range: 124-661 mm Bioclimatic Model: Combination of Annual Mean Temperature and Precipitation Weaknesses of Bioclimatic Models ● Doesn’t take into consideration: ○ biotic interactions ○ physiological limitations ○ evolutionary change ○ dispersal ability ● Invasive species are still spreading ○ not necessarily at equilibrium with their environment! ● Current distributions are not reliable in predicting future risk. Literature Review: Dorcas et al. ● Monitored 10 wild-captured pythons ● Recorded air temp, water temp, underground refuge temp ● Observed deaths during cold winter temps ● Avg. min. temperature at death: 7.65 c Physiological Model Min Jan Temp > 7.65 Weaknesses of Physiological Models ● Small samples sizes of studies ● Flawed experimental design (done on captive snakes, etc.) ● Limited data So...which is the optimal model? Neither! Ideal: integrated model including physiological limitations, climatic of invaded and native range, interactions, adaptations and dispersal ability. Sources http://www.evergladeshub.com/lit/pdf09/Rodda09BioInvas-103-PythoNorth.pdf http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1859&context=icwdm_usdanwrc&seiredir=1&referer=http%3A%2F%2Fscholar.google.com%2Fscholar%3Fq%3Dburmese%2Bpython%2Bi nvasive%26btnG%3D%26hl%3Den%26as_sdt%3D0%252C22#search=%22burmese%20python%20i nvasive%22 http://usark.org/wp-content/uploads/2012/05/Cold%20pythons%20(2).pdf http://link.springer.com/article/10.1007/s10530-010-9797-5/fulltext.html http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0002931 Questions?