Persistence and Stability of the Component Helminth Community of the Sagebrush Lizard, Sceloporus Graciosus (Phrynosomatidae) from Los Angeles County, California, 1972-1973, 1986-1996

Article excerpt

ABSTRACT.-One thousand three hundred eighty-eight adult Sceloporus graciosus collected 1972-1973, 198-1996 from the San Gabriel Mountains, Los Angeles County, California were examined for helminths. The component helminth community consisted of one species of cestode, Oochoristica scelopori and three species of nematodes, Atractis penneri, Physaloptera retusa and Spauligodon giganticus. No significant differences by year were found for mean infrapopulations of Oochoristica scelopoi, Physaloptera retusa and Spauligodon giganticus (Kruskal-Wallis statistic = 3.9, 8 df; 17.8, 10 df; 7.0, 10 df, respectively, P > 0.05). Mean infrapopulations of Atractis penneri by year were significantly different (Kruskal-Wallis statistic = 24.5, 8 df, P < 0.05). The component helminth community of Sceloporus graciosus was persistent and, with the exception of A. penneri, stable.

INTRODUCTION

The sagebrush lizard, Sceloporus graciosus Baird and Girard, 1852, occurs from central Washington, southern Idaho, southern Montana and western Colorado to northwestern New Mexico, northern Arizona and northern Baja California; it is an oviparous lizard that deposits one or two clutches of 28 eggs during June-August (Stebbins, 1985). In southern California, these abundant, easily collected lizards are active March-October and spend the winter in hibernation (Goldberg, 1975).

Parasite community structure is hierarchical: a parasite infrapopulation includes all members of a single species of parasite within an individual host (Esch et al., 1975), a parasite infracommunity includes all the infrapopulations within an individual host (Bush and Holmes, 1986), and a component parasite community represents all of the infracommunities within a given host population (Holmes and Price, 1986). Parasite communities may be persistent, a qualitative measure based upon the relative constancy (i.e., lack of statistical difference between samples) of species abundances over time (Meffe and Minckley, 1987). While there are many reports of helminths in lizards (Schmidt, 1986; Baker, 1987), there are few longitudinal studies (Bursey and Goldberg, 1994; Telford, 1997) of helminth communities within lizard populations. The purpose of this study was to examine persistence and stability of the component helminth community in a population of the southern sagebrush lizard Sceloporus graciosus vandenburgianus Cope, 1896, from southern California.

MATERIALS AND METHODS

One thousand three hundred eighty-eight adult Sceloporus graciosus (snout-vent length, SVL = 59.1 mm 4.8 SD; range = 47-73 mm) were examined for helminths. Two collections of lizards were used for this study: monthly samples collected April-September 1972-1973 and annual samples collected April-May 1986-1996. All lizards were collected by hand-held noose on Windy Gap Trail (elev., 1889 m; 3421'N, 11748'W), Crystal Lake area, San Gabriel Mountains, Los Angeles County, California. Lizards were preserved in 10% formalin and later transferred to ethanol for storage.

The body cavity of each lizard was opened by a longitudinal incision from vent to throat and the gastrointestinal tract was removed by cutting across the esophagus and rectum. The esophagus, stomach, small intestine and large intestine were slit longitudinally and examined for helminths separately with a dissecting microscope. Each helminth was removed, placed on a glass slide in a drop of undiluted glycerol and covered with a glass coverslip for examination with a compound microscope. Selected cestodes were stained by the standard regressive hematoxylin method (Schmidt, 1986). Lizards were deposited in the herpetology collection of the Natural History Museum of Los Angeles County. Voucher helminths were deposited in the U.S. National Parasite Collection, Beltsville, Maryland: Oochoristica scelopori, 86879; Atractis penneri, 86880; Physaloptera retusa, 86881; Spauligodon giganticus, 86882.

RESULTS AND DISCUSSION

The Crystal Lake population of Sceloporus graciosus harbored one cestode species, Oochoristica scelop/i Voge and Fox, 1950, and three nematode species, Atractis penneri (Gambino, 1957) Baker, 1987, Physaloptera retusa Rudolphi, 1819 and Spauligodon giganticus (Read and Amrein, 1953) Skrjabin, Schikhobalova and Lagodovskaja, 1960. …