Niche Relationships and Interspecific Interactions in Antiguan Lizard Communities

Anolis lizards are the focus of most Caribbean lizard community ecology studies with few studies including other common species that might influence community structure. To study niche relationships and interspecific interactions in Antiguan lizard communities, we used five offshore islands with varying combinations of three diurnal lizards: Ameiva griswoldi, Anolis leachii, and Anolis wattsi. We collected data on perch height, substrate, thermal microhabitat, body size, head length, daily activity, and abundance to characterize the ecological niche of each species. Ameiva griswoldi was more similar to A. leachii in size and daily activity, but more similar to A. wattsi in perch height, and A. leachii and A. wattsi were more similar in thermal microhabitat. This pattern of niche differentiation was consistent with niche complementarity, where species are similar on some niche axes but differ on others. Using the same niche characteristics as in species comparisons, we tested for a niche shift among islands for A. wattsi. In the absence of A. griswoldi, A. wattsi used lower perches, sunnier microhabitats, and was found more often on the ground. In contrast, with A. leachii absent, A. wattsi perched higher, more often in the shade, and on trunks. Furthermore, A. wattsi was most abundant when with A. leachii only, but least abundant when alone with A. griswoldi. These results suggest interspecific interactions, most likely due to competition and intraguild predation, are important for structuring Antiguan lizard communities.

Fig. 1

Map of the Northern Lesser Antilles with an inset of the North Sound area of Antigua showing the five offshore islands used in this study.

Fig. 2

Frequency of substrate use for the three Antiguan lizard species. Sample sizes are shown in parentheses.

Fig. 3

Perch heights (mean ± 1 SE) for the three Antiguan lizard species in one-hour time increments from 0500 to 1900 h.

Fig. 4

Distributions of female and male head lengths and snout–vent lengths (SVL) for the three Antiguan lizard species. Sample sizes are shown in parentheses.

Fig. 5

Abundance (mean ± 1 SE) for the three Antiguan lizard species in one-hour time increments from 0500–1900 h. Data are from visual encounter surveys.

Fig. 6

Mean perch height of Anolis wattsi in one-hour time increments from 0500–1900 h on each of the five offshore islands. Perch height data from both visual encounter surveys and habitat observations are shown. SE bars are omitted for clarity.

Fig. 7

Percentage of sunny or shady thermal microhabitat observations for Anolis wattsi in two-hour time increments from 0500–1900 h on each of the five offshore islands.

Fig. 8

Mean abundance of Ameiva griswoldi, Anolis leachii, and Anolis wattsi in one-hour time increments from 0500–1900 h on each of the five offshore islands. SE bars are omitted for clarity.

Contributor Notes

Associate Editor: J. W. Snodgrass.

¹ Department of Biology, Campus Box 1137, Washington University, St. Louis, Missouri 63130. Present address: Museum of Vertebrate Zoology, 3101 Valley Life Sciences Building, University of California, Berkeley, California 94720; E-mail: kolbe@berkeley.edu. Send reprint requests to this address.

² Department of Biology, Black Hills State University, 1200 University Street Unit 9044, Spearfish, South Dakota 57799.

Received: 18 Jan 2007

Accepted: 30 Oct 2007