Composition of Helminth Communities in Montane and Lowland Populations of the Western Fence Lizard, Sceloporus Occidentalis from Los Angeles County, California

Article excerpt

ABSTRACT.-Five hundred seventy-two Sceloporus occidentalis from Los Angeles County, California, were examined for helminths: 200 from the San Gabriel Mountains (montane, ca. 1584 m elevation) and 372 from the Puente Hills (lowland, ca. 150 m elevation). The component helminth community of the montane fence lizard population consisted of four species: two species of cestodes, Mesocestoides sp. and Oochoristica scelopon and two species of nematodes, Physaloptera retusa and Spauligodon giganticus. The component helminth community of the lowland fence lizard population contained three species: Mesocestoides sp., Physaloptera retusa and unidentified nematode acuard larvae. The two helminth communities are dissimilar in composition.

INTRODUCTION

The lizard genus Sceloporus (Phrynosomatidae) has proven to be valuable for studies of the composition of helminth communities in lizards. Goldberg and Bursey (1990, 1991) and Goldberg et al. (1993a, 1994, 1995a) have demonstrated that helminth communities of single populations of Sceloporus spp. are poor in species and characterized by low diversity and high dominance. Studies of disjunct populations of Sceloporus jarrovii from similar habitats (Goldberg et al., 1995b, 1996a) and surveys of helminths from populations of Sceloporus scalaris from different habitats (Goldberg and Bursey, 1992; Goldberg et al., 1996b) have demonstrated that helminth communities often differ in composition. The purpose of this investigation was to compare composition of helminth communities between two southern California populations of the western fence lizard, Sceloporus occidentalis Baird and Girard, 1852 occupying different, but near-by habitats.

MATERIALS AND METHODS

From February 1971 through November 1973, 638 Sceloporus occidentalis were collected by hand-held noose in the San Gabriel Mountains, at the junction of California Hwy. 39 and the road to Crystal Lake Campground (3418'N, 117o50'W) at ca. 1584 m elevation and in the Puente Hills, Whittier, Los Angeles County, California (3401'N, 117o57'W) at ca. 150 m elevation. The two populations were separated by ca. 1434 m in elevation and 64 km in distance.

Lizards were killed by injection of sodium pentobarbital, weighed, measured and used in a study of seasonal changes in gonads and fat bodies (Goldberg, 1974). The lizards were fixed in 10% formalin, preserved in 70% ethanol and deposited in the herpetology collection of the Natural History Museum of Los Angeles County. In 1996, 572 lizards of this collection were examined for helminths: 200 (107 female, 93 male; snout-vent length (SVL) = 66.0 mm 12.0 SD, range 25-81 mm) from the San Gabriel Mountains; 372 (208 female, 164 male; SVL = 63.6 mm + 6.8 SD; range 23-77 mm) from the Puente Hills. The San Gabriel Mountain population was significantly larger (SVL) than the Whittier population, Kruskal-Wallis test = 15.27, 1 df, P < 0.001.

The habitat occupied by Sceloporus occidentalis in the San Gabriel Mountains lies within the Sierran faunal province (Powell and Hogue, 1979) and consisted primarily of evergreen forest (Pinus ponderosa, P jeffreyi, Pseudotsuga macrocarpa, Calocedrus decurrens) with a predominance of chaparral vegetation (Arctostaphylos sp., Cercocarpus sp.) in open areas. The habitat in the Puente Hills lies within the Californian faunal province (Powell and Hogue, 1979) and consisted of canyon bottoms dominated by coast live oak (Quercus agr/folia) with some western sycamore (Platanus racemosa) and eucalyptus (Eucalyptus sp.). The climate of both habitats is Mediterranean-type characterized by summer drought and winter rain (Bakker, 1972), although the Puente Hills habitat is more arid than the San Gabriel Mountains habitat (Powell and Hogue, 1979). Temperature data (U.S. Department of Commerce, 1971-1973) from Mt. Wilson, 21 km W of the San Gabriel Mountain study area and California State Polytechnic University, Pomona, 23 km E of Whittier (the nearest temperature weather stations) showed that mean daily temperatures of the two habitats were significantly different during the collection period (paired t test = 9. …