Effects of the Brown Anole Invasion and Betelnut Palm Planting on Arthropod Diversity in Southern Taiwan

Abstract

The brown anole ( Anolis sagrei ) occurs naturally in various localities in Central America, and an exotic invasive population was first reported in Sheishan District, Chiayi County, Taiwan, in 2000. Previous studies showed that following the invasion of A. sagrei , the diversity and abundance of local terrestrial arthropods, such as orb spiders and arboreal insects, were severely affected. In this study, we assessed the impact of A. sagrei on arthropod diversity in Taiwan by comparing spider and insect diversities among betelnut palm plantations, in which this lizard species was either present or absent, and a secondary forest. In addition, enclosures were established in which the density of A. sagrei was manipulated to investigate the effect of this predator on spiders. The results of a lizard stomach content analysis showed that spiders comprised 7% and insects 90% of the prey consumed. Among the insects consumed by A. sagrei , more than 50% were ants. The abundances of the major arthropod prey of A. sagrei , such as jumping spiders and hymenopterans, in the lizard-present sites were much lower than in the lizard-removed sites. The enclosure experiments also showed that predation by the lizards significantly reduced the abundance of jumping spiders. All these results indicated that the introduced lizard greatly affected the diversity and abundance of terrestrial arthropods in agricultural areas in southern Taiwan.

Frequency of tail loss reflects variation in predation levels, predator efficiency, and the behaviour of three populations of brown anoles

“…It is unlikely that all the anoles present were seen at each pass because anoles can be remarkably common in suitable, particularly disturbed or anthropogenically altered, sites (e.g. 0.25 to 0.97 individuals/m 2 ; Lee et al ., 1989; Huang et al ., 2008). Surveys lasted around 1 h each and were carried out between 10.00 h and 12.00 h. We are confident that this pattern of repeated independent surveys of each population yielded a representative sample of individuals and minimized repeated sampling of the same individuals.…”

Invasive aliens on tropical East Asian islands

“…Moreover, the forest invasions by vertebrates in Hong Kong appear to be exceptional. The Central American brown anole, Anolis sagrei, is abundant in betelnut plantations in southern Taiwan, where it reduces the diversity and abundance of terrestrial arthropods, but it is rare in secondary forests (Huang et al 2008). However, the capture of two rats from the commensal Rattus rattus complex in primary lowland rain forest in Borneo may be a warning sign (Wells et al 2006).…”

Additional notes on the diet of Japalura swinhonis (Agamidae) from southwestern Taiwan, with comments about its dietary overlap with the sympatric Anolis sagrei (Polychrotidae)

“…The dietary descriptions for J. swinhonis from Orchid Island (HUANG, 2007), and northern (KUO et al, 2007) and southwestern (this study) Taiwan were incorporated for comparison with the dietary descriptions for A. sagrei from Santzepu, southwestern Taiwan (HUANG et al, 2008a;NORVAL et al, 2010). Because not all the dietary items were identified to the family level, the order level was used in the analysis as the resource category.…”

“…Anolis sagrei is an aggres-sive competitor that has been shown to displace other species of lizards from their habitats (SALZBURG, 1984;TOKARZ & BECK, 1987;LOSOS et al, 1993;LOSOS & SPILLER, 1999). Ongoing research on this species in Taiwan indicates that in areas disturbed by anthropogenic activities, it is increasingly becoming part of local ecosystems, both as predator (HUANG et al, 2008a;NORVAL et al, 2010) and prey (NORVAL et al, 2004(NORVAL et al, , 2007(NORVAL et al, , 2011NORVAL & MAO, 2008;CHIU et al, 2011).…”