Buckland Steeves, Cole Nik C, Aguirre-Gutiérrez Jesús, Gallagher Laura E, Henshaw Sion M, Besnard Aurélien, Tucker Rachel M, Bachraz Vishnu, Ruhomaun Kevin, Harris Stephen
School of Biological Sciences, University of Bristol, Bristol, United Kingdom; National Parks & Conservation Service, Reduit, Mauritius.
School of Biological Sciences, University of Bristol, Bristol, United Kingdom; Durrell Wildlife Conservation Trust, Jersey, Channel Islands; Mauritian Wildlife Foundation, Vacoas, Mauritius.
PLoS One. 2014 Apr 30;9(4):e88798. doi: 10.1371/journal.pone.0088798. eCollection 2014.
The invasion of the giant Madagascar day gecko Phelsuma grandis has increased the threats to the four endemic Mauritian day geckos (Phelsuma spp.) that have survived on mainland Mauritius. We had two main aims: (i) to predict the spatial distribution and overlap of P. grandis and the endemic geckos at a landscape level; and (ii) to investigate the effects of P. grandis on the abundance and risks of extinction of the endemic geckos at a local scale. An ensemble forecasting approach was used to predict the spatial distribution and overlap of P. grandis and the endemic geckos. We used hierarchical binomial mixture models and repeated visual estimate surveys to calculate the abundance of the endemic geckos in sites with and without P. grandis. The predicted range of each species varied from 85 km2 to 376 km2. Sixty percent of the predicted range of P. grandis overlapped with the combined predicted ranges of the four endemic geckos; 15% of the combined predicted ranges of the four endemic geckos overlapped with P. grandis. Levin's niche breadth varied from 0.140 to 0.652 between P. grandis and the four endemic geckos. The abundance of endemic geckos was 89% lower in sites with P. grandis compared to sites without P. grandis, and the endemic geckos had been extirpated at four of ten sites we surveyed with P. grandis. Species Distribution Modelling, together with the breadth metrics, predicted that P. grandis can partly share the equivalent niche with endemic species and survive in a range of environmental conditions. We provide strong evidence that smaller endemic geckos are unlikely to survive in sympatry with P. grandis. This is a cause of concern in both Mauritius and other countries with endemic species of Phelsuma.
马达加斯加巨型日行壁虎（Phelsuma grandis）的入侵增加了对毛里求斯本土四种日行壁虎（Phelsuma spp.）的威胁，这四种壁虎在毛里求斯主岛上存活了下来。我们有两个主要目标：（i）在景观层面预测大壁虎和本土壁虎的空间分布及重叠情况；（ii）在局部尺度上研究大壁虎对本土壁虎数量及灭绝风险的影响。采用了一种集成预测方法来预测大壁虎和本土壁虎的空间分布及重叠情况。我们使用分层二项混合模型和重复的视觉估计调查来计算有和没有大壁虎的地点的本土壁虎数量。每个物种的预测范围从85平方公里到376平方公里不等。大壁虎预测范围的60%与四种本土壁虎的综合预测范围重叠；四种本土壁虎综合预测范围的15%与大壁虎重叠。大壁虎和四种本土壁虎之间的莱文生态位宽度在0.140到0.652之间。与没有大壁虎的地点相比，有大壁虎的地点本土壁虎数量低89%，并且在我们调查的有大壁虎的十个地点中的四个地点，本土壁虎已经灭绝。物种分布模型与宽度指标一起预测，大壁虎可以部分与本土物种共享等效生态位，并在一系列环境条件下生存。我们提供了有力证据，表明较小的本土壁虎不太可能与大壁虎共存。这在毛里求斯以及其他有本土日行壁虎物种的国家都是一个令人担忧的问题。
