scholarly journals Predicting terrestrial dispersal corridors of the invasive African clawed frog Xenopus laevis in Portugal

NeoBiota ◽  
2021 ◽  
Vol 64 ◽  
pp. 103-118
Author(s):  
Philipp Ginal ◽  
Francisco D. Moreira ◽  
Raquel Marques ◽  
Rui Rebelo ◽  
Dennis Rödder
Keyword(s):  
Invasive Species ◽  
Xenopus Laevis ◽  
Vegetation Index ◽  
Stepping Stones ◽  
Dispersal Patterns ◽  
Water Index ◽  
African Clawed Frog ◽  
Normalised Difference Vegetation Index ◽  
Dispersal Corridors ◽  
Clawed Frog

Invasive species, such as the mainly aquatic African clawed frog Xenopus laevis, are a main threat to global biodiversity. The identification of dispersal corridors is necessary to restrict further expansion of these species and help to elaborate management plans for their control and eradication. Here we use remote sensing derived resistance surfaces, based on the normalised difference vegetation index (NDVI) and the normalised difference water index (NDWI) accounting for behavioural and physiological dispersal limitations of the species, in combination with elevation layers, to determine fine scale dispersal patterns of invasive populations of X. laevis in Portugal, where the frog had established populations in two rivers. We reconstruct past dispersal routes between these two invaded rivers and highlight high risk areas for future expansion. Our models suggest terrestrial dispersal corridors that connect both invaded rivers and identify artificial water bodies as stepping stones for overland movement of X. laevis. Additionally, we found several potential stepping stones into novel areas and provide concrete information for invasive species management.

Plotting the course of an African clawed frog invasion in Western France

2006 ◽  
Vol 56 (1) ◽  
pp. 95-102 ◽  
Author(s):  
G. John Measey ◽  
Antoine Fouquet
Keyword(s):  
Invasive Species ◽  
Xenopus Laevis ◽  
South African ◽  
European Countries ◽  
Aquatic Species ◽  
Release Point ◽  
African Clawed Frog ◽  
Rivers And Streams ◽  
Considerable Impact ◽  
Clawed Frog

AbstractThe African clawed frog, Xenopus laevis, is an invasive species with considerable impact in mediterranean climates, similar to its native South African Cape. A population has been established in western France since the early 1980s with a single, known, original release point. This study attempts to determine the limits of the invasion by trapping in 169 ponds in 2001 and 2002. Subsequent trapping of 192 ponds in 2003 and 2004 was undertaken in order to chart the progress of invasion, and to test the hypothesis that ponds were mostly colonised using rivers and streams as corridors. Of ponds without X. laevis in 2001/2002, 36% were found to have been colonised by 2003/2004. The findings clearly show that, while lotic corridors are used by this principally aquatic species, most ponds are colonised through overland migration. The consequences of this finding for invasions in France and other European countries are briefly discussed.

scholarly journals Developmental changes of purinergic control of intestinal motor activity during metamorphosis in the African clawed frog, Xenopus laevis

2007 ◽  
Vol 292 (5) ◽  
pp. R1916-R1925 ◽  
Author(s):  
Monika Sundqvist
Keyword(s):  
Xenopus Laevis ◽  
Motor Activity ◽  
Receptor Antagonist ◽  
Circular Muscle ◽  
Developmental Changes ◽  
Disulfonic Acid ◽  
Developmental Phase ◽  
African Clawed Frog ◽  
Low Concentrations ◽  
Clawed Frog

Little is known about the purinergic regulation of intestinal motor activity in amphibians. Purinergic control of intestinal motility is subject to changes during development in mammals. The aim of this study was to investigate purinergic control of intestinal smooth muscle in the amphibian Xenopus laevis and explore possible changes in this system during the developmental phase of metamorphosis. Effects of purinergic compounds on mean force and contraction frequency in intestinal circular muscle strips from prometamorphic, metamorphic, and juvenile animals were investigated. Before metamorphosis, low concentrations of ATP reduced motor activity, whereas the effects were reversed at higher concentrations. ATP-induced relaxation was not inhibited by the P2-receptor antagonist pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS) but was blocked by the ecto-nucleotidase inhibitor 6- N, N-diethyl-d-β,γ-dibromomethylene ATP ( ARL67256 ), indicating that an ATP-derived metabolite mediated the relaxation response at this stage. Adenosine induced relaxation before, during, and after metamorphosis, which was blocked by the A1-receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). The stable ATP-analog adenosine 5′-[γ-thio]-triphosphate (ATPγS) and 2-methylthioATP (2-MeSATP) elicited contractions in the circular muscle strips in prometamorphic tadpoles. However, in juvenile froglets, 2-MeSATP caused relaxation, as did ATPγS at low concentrations. The P2Y11/P2X1-receptor antagonist NF157 antagonized the ATPγS-induced relaxation. The P2X-preferring agonist α-β-methyleneadenosine 5′-triphosphate (α-β-MeATP) evoked PPADS-sensitive increases in mean force at all stages investigated. This study demonstrates the existence of an adenosine A1-like receptor mediating relaxation and a P2X-like receptor mediating contraction in the X. laevis gut before, during, and after metamorphosis. Furthermore, the development of a P2Y11-like receptor-mediated relaxation during metamorphosis is shown.

scholarly journals Optical sensors for variable rate nitrogen application in dairy pastures

2017 ◽  
Vol 79 ◽  
pp. 223-227
Author(s):  
K. Wigley ◽  
J.L. Owens ◽  
J.A.K. Trethewey ◽  
D.C. Ekanayake ◽  
R.L. Roten ◽  
...  
Keyword(s):  
Optical Sensors ◽  
Vegetation Index ◽  
N Uptake ◽  
Variable Rate ◽  
Water Index ◽  
Foliar N ◽  
Normalised Difference Vegetation Index ◽  
Fertiliser Application ◽  
Vegetative Indices ◽  
Simple Ratio

Reducing the amount of nitrogen (N) fertiliser applied to dairy pastures down to agronomically optimised levels would have positive economic and environmental results. The ability of commercially available optical sensors to estimate biomass yield and foliar-N uptake in pastures was investigated. Vegetative indices (Simple Ratio, SR; Water Index, WI; and Normalised Difference Vegetation Index, NDVI) from two active optical reflectance sensors (N-Sensor, Yara; and Greenseeker, Trimble) were compared with manually measured biomass and N-uptake in above-ground foliage. There were three measurements over time, from pastures that had received different N fertiliser applications rates (0, 10, 20, 40 and 80 kg N/ha). It was found that the sensors were able to detect differences in biomass and foliar N-uptake following defoliation of grazed pastures. The tested optical sensors have the potential to inform a real-time variable rate fertiliser application system. Keywords: pasture, nitrogen, optical sensors

scholarly journals Toxic effects of carbendazim andn-butyl isocyanate, metabolites of the fungicide benomyl, on early development in the African clawed frog,Xenopus laevis

2008 ◽  
Vol 23 (1) ◽  
pp. 131-144 ◽  
Author(s):  
Chun-Sik Yoon ◽  
Jung-Hyo Jin ◽  
Joo-Hung Park ◽  
Chang-Yeol Yeo ◽  
Song-Ja Kim ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Early Development ◽  
Toxic Effects ◽  
African Clawed Frog ◽  
Clawed Frog

scholarly journals First parasitological study of the African clawed frog (Xenopus laevis, Amphibia) in Chile

2017 ◽  
Vol 26 (2) ◽  
pp. 243-247 ◽  
Author(s):  
Cristóbal Castillo ◽  
Gabriel Lobos ◽  
Daniel González-Acuña ◽  
Lucila Moreno ◽  
Cynthya Elizabeth González ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Introduced Species ◽  
Batrachochytrium Dendrobatidis ◽  
First Record ◽  
Central Chile ◽  
African Clawed Frog ◽  
Parasite Richness ◽  
Native Birds ◽  
Clawed Frog ◽  
Parasitological Study

Abstract Introduced species can arrive into new territories with parasites; however, these species are expected to face lower parasite richness than in their original regions. Both introduced hosts and parasites can affect native fauna. Since their release into the wild in Chile following laboratory use, Xenopus laevis Daudin, 1802 has widely spread throughout central Chile. The only pathogen described on the host is the fungus Batrachochytrium dendrobatidis Longcore, Pessier, Nichols, 1999; thus, this is the first parasitological study of this species in Chile. In 10 localities in central Chile, 179 specimens of X. laevis were captured and examined for parasites in the gastrointestinal tube, cavities, lungs, liver, and skin. Only nine specimens of the genus Contracaecum Railliet, Henry, 1912 were found in six specimens of X. laevis from a private dam in La Patagua. It is likely that these parasites originated from species of native birds. This is the first record of Contracaecum sp. in Chilean amphibians.

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