Meeting Abstract
Human activity is responsible for numerous introductions of species to areas outside of native ranges. However, because many introduced populations may not persist long enough to be noticed, and hence remain unreported, the factors responsible for population establishment or extinction are often difficult to quantify. We studied a viable population of brown anoles (Anolis sagrei; native to Cuba and The Bahamas) at a temperate latitude that is farther north than its continuous invasive range in the southeast United States. This population was first reported in 2006 at a commercial greenhouse near Auburn, Alabama and likely arrived via propagules transplanted in ornamental plants. The warm confines of the greenhouse presumably shielded this population from lethally cold winters for at least 12 years (~12 generations). However, the greenhouse rapidly degraded after the facility went out of business (in 2016) and lost its roof due to strong winds from Hurricane Irma (in 2017). Prior to winter 2017, individuals of both sexes and all age classes were present (from eggs to adults), and the population size was at least 225 individuals. Post-winter surveys in 2018 revealed that no A. sagrei survived winter. Without the thermal buffering of the greenhouse roof, temperatures dropped well below the population’s critical thermal minimum, and individuals were presumably exposed to lethally low temperatures. This study provides a rare documentation of an extinction of a viable introduced population and illustrates the role that anthropogenic structures and natural weather events play in population establishment and extinction.
