The effects of Anolis sagrei, an exotic lizard, on spider diversity in Taiwan. (2/3) (NSC 94-2621-B-029-001)


The exotic invasive lizard, Anolis sagrei, has caused severe negative effects on web spiders, as has been determined in studies over the past twenty years in the Caribbean. In Taiwan, A. sagrei, was first recorded in 2000, and their introduction was without a doubt through anthropogenic activities. It has been determined that these lizards reduce the spider diversity significantly in betelnut palm plantations(Areca catechu). It was found that the lizards preyed on spiders and ants mostly, and reduced their numbers significantly. Spiders are the top invertebrate predators in terrestrial ecosystem, as the abundance of them are reduced organisms exhibiting trophic interactions with spiders will be impacted. Previous studies showed that ground spiders preyed on springtails (Collembola), reduced their population density, lowered the litter disappearance indirectly, hence affected the ecosystem functioning. In this study, by addressing the following aspects, the impact of the invasive species, A. sagrei, on the ecosystem can be determined: 1) the impacts of lizards on spider and ant diversity, 2) the impact of lizards on detritus ecosystem, 3) will presence of lizards affect litter disappearance rate? 4) the role played by lizards, spiders, ants, springtails, and litters in betel nut plantation ecosystem. This study will be conducted in Santzepu, Chiayi County in the southwestern part of Taiwan. Eight pairs of enclosures are set up in two study sites respectively. Each enclosure is divided into two sub-enclosures with the lizards present and with the lizards removed. The study will be conducted from March to October, 2006. The lizard density in the enclosures will be monitored every week and diversities of spiders, ants, and springtails will be surveyed every two weeks. Litterbags containing 2 g of dry mass of Bidens pilosa, Panicum maximum, and Areca catechu will be placed in the enclosures and litter disappearance rates will be estimated every month. By comparing the diversities and abundance of organisms in different trophic levels, hopefully the impacts of the invasive A. sagrei on ecosystem can be realized.

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Updated: Jan-24-2014 11:34:24 (Taiwan, GMT+08:00).