Limits...
Extinction of an introduced warm-climate alien species, Xenopus laevis, by extreme weather events.

Tinsley RC, Stott LC, Viney ME, Mable BK, Tinsley MC - Biol. Invasions (2015)

Bottom Line: 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 extinction of X. laevis in these areas indicates that even relatively long-established alien species remain vulnerable to rare extreme weather conditions.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol, BS8 1TQ UK.

ABSTRACT

Invasive, non-native species represent a major threat to biodiversity worldwide. The African amphibian Xenopus laevis is 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 of X. laevis in these areas indicates that even relatively long-established alien species remain vulnerable to rare extreme weather conditions.

No MeSH data available.


Related in: MedlinePlus

Distribution of Xenopus laevis and of fieldwork trapping in Wales: Alun valley and surrounding area, centred on 51°27′50″N, 3°34′14″W, south of Bridgend, Mid-Glamorgan. Blue circles sites of occurrence of X. laevis in the period 1981–2008 (see text for specific years of records). Red circles positions of traps in 2010 and 2011 with numbers of trap-sessions in each locality, a–n, and numbers of X. laevis caught. Paired lines group together data for a series of habitats, single lines with arrows indicate specific ponds
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4581400&req=5

Fig1: Distribution of Xenopus laevis and of fieldwork trapping in Wales: Alun valley and surrounding area, centred on 51°27′50″N, 3°34′14″W, south of Bridgend, Mid-Glamorgan. Blue circles sites of occurrence of X. laevis in the period 1981–2008 (see text for specific years of records). Red circles positions of traps in 2010 and 2011 with numbers of trap-sessions in each locality, a–n, and numbers of X. laevis caught. Paired lines group together data for a series of habitats, single lines with arrows indicate specific ponds

Mentions: The fieldwork area centres on the Alun valley, near Bridgend, adjacent to the Bristol Channel (Fig. 1). A plateau of Liassic limestone (40–90 m a.s.l.) supports pasture farmland from which the river Alun descends into a wooded valley in Carboniferous limestone. The drainage experiences extremes of water flow: after prolonged periods without rain the river disappears into underground fissures and the riverbed is dry, but heavy rain produces torrential floods, often 1–2 m deep. The area has stone-built livestock watering ponds constructed in the 19th century, typically over a spring or seepage that maintains permanent water even during drought. One such site is a pond at Croescwtta farm (Fig. 1k), area 110 m2, located about 400 m up-slope of the river course but without direct connection to it. In the 1990s, water depth was about 60 cm but sediment accumulated so that, during drought in the late 2000s, the water was only a few centimetres deep above about 1.2 m of anoxic mud. Water temperatures on the pond substrate in 2006–2008 were <10 °C for over 6 months each year (mid-October to late April), >15 °C for 4–5 months and >18 °C for only a few days (Tinsley et al. 2011a). Xenopus laevis may experience warmer conditions (but a greater risk of predation) in surface water in sunshine, up to 23 °C (Tinsley et al. 2011b).Fig. 1


Extinction of an introduced warm-climate alien species, Xenopus laevis, by extreme weather events.

Tinsley RC, Stott LC, Viney ME, Mable BK, Tinsley MC - Biol. Invasions (2015)

Distribution of Xenopus laevis and of fieldwork trapping in Wales: Alun valley and surrounding area, centred on 51°27′50″N, 3°34′14″W, south of Bridgend, Mid-Glamorgan. Blue circles sites of occurrence of X. laevis in the period 1981–2008 (see text for specific years of records). Red circles positions of traps in 2010 and 2011 with numbers of trap-sessions in each locality, a–n, and numbers of X. laevis caught. Paired lines group together data for a series of habitats, single lines with arrows indicate specific ponds
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581400&req=5

Fig1: Distribution of Xenopus laevis and of fieldwork trapping in Wales: Alun valley and surrounding area, centred on 51°27′50″N, 3°34′14″W, south of Bridgend, Mid-Glamorgan. Blue circles sites of occurrence of X. laevis in the period 1981–2008 (see text for specific years of records). Red circles positions of traps in 2010 and 2011 with numbers of trap-sessions in each locality, a–n, and numbers of X. laevis caught. Paired lines group together data for a series of habitats, single lines with arrows indicate specific ponds
Mentions: The fieldwork area centres on the Alun valley, near Bridgend, adjacent to the Bristol Channel (Fig. 1). A plateau of Liassic limestone (40–90 m a.s.l.) supports pasture farmland from which the river Alun descends into a wooded valley in Carboniferous limestone. The drainage experiences extremes of water flow: after prolonged periods without rain the river disappears into underground fissures and the riverbed is dry, but heavy rain produces torrential floods, often 1–2 m deep. The area has stone-built livestock watering ponds constructed in the 19th century, typically over a spring or seepage that maintains permanent water even during drought. One such site is a pond at Croescwtta farm (Fig. 1k), area 110 m2, located about 400 m up-slope of the river course but without direct connection to it. In the 1990s, water depth was about 60 cm but sediment accumulated so that, during drought in the late 2000s, the water was only a few centimetres deep above about 1.2 m of anoxic mud. Water temperatures on the pond substrate in 2006–2008 were <10 °C for over 6 months each year (mid-October to late April), >15 °C for 4–5 months and >18 °C for only a few days (Tinsley et al. 2011a). Xenopus laevis may experience warmer conditions (but a greater risk of predation) in surface water in sunshine, up to 23 °C (Tinsley et al. 2011b).Fig. 1

Bottom Line: 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 extinction of X. laevis in these areas indicates that even relatively long-established alien species remain vulnerable to rare extreme weather conditions.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol, BS8 1TQ UK.

ABSTRACT

Invasive, non-native species represent a major threat to biodiversity worldwide. The African amphibian Xenopus laevis is 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 of X. laevis in these areas indicates that even relatively long-established alien species remain vulnerable to rare extreme weather conditions.

No MeSH data available.


Related in: MedlinePlus