title: Extinction of an introduced warm-climate alien species,Xenopus laevis, by extreme weather events.
abstract: Invasive, non-native species represent a major threat to biodiversity worldwide. The African amphibianXenopus laevisis widely regarded as an invasive species and a threat to local faunas. Populations originating at the Western Cape, South Africa, have been introduced on four continents, mostly in areas with a similar Mediterranean climate. Some introduced populations are also established in cooler environments where persistence for many decades suggests a capacity for long-term adaptation. In these cases, recent climate warming might enhance invasion ability, favouring range expansion, population growth and negative effects on native faunas. In the cool temperate UK, populations have been established for about 50 years in Wales and for an unknown period, probably >20 years, in England (Lincolnshire). Our field studies over 30 and 10 years, respectively, show that in favourable conditions there may be good recruitment, fast individual growth rates and large body size; maximum longevity exceeds 23 years. Nevertheless, areas of distribution remained limited, with numbers <500 in each population. In 2010, only a single individual was captured at each locality and further searching failed to record any others in repeated sampling up to 2014. We conclude that both populations are now extinct. The winters of 2009-2010 and 2010-2011 experienced extreme cold and drought (December 2010 was the coldest in 120 years and the third driest in 100 years). The extinction ofX. laevisin these areas indicates that even relatively long-established alien species remain vulnerable to rare extreme weather conditions.
authors.affiliation: School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol, BS8 1TQ UK.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Tinsley
authors.affiliation: School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol, BS8 1TQ UK.
authors.forename: Lucy C
authors.initials: LC
authors.lastname: Stott
authors.affiliation: School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol, BS8 1TQ UK.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Viney
authors.affiliation: Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ UK.
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Mable
authors.affiliation: School of Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA UK.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Tinsley
keywords: Climate change; Extinction; Extreme weather; Invasive species; Xenopus laevis