Lizards In Areas Research Articles

Phenotypic shifts in urban areas in the tropical lizard Anolis cristatellus.

Urbanization is an increasingly important dimension of global change, and urban areas likely impose significant natural selection on the species that reside within them. Although many species of plants and animals can survive in urban areas, so far relatively little research has investigated whether such populations have adapted (in an evolutionary sense) to their newfound milieu. Even less of this work has taken place in tropical regions, many of which have experienced dramatic growth and intensification of urbanization in recent decades. In the present study, we focus on the neotropical lizard, Anolis cristatellus. We tested whether lizard ecology and morphology differ between urban and natural areas in three of the most populous municipalities on the island of Puerto Rico. We found that environmental conditions including temperature, humidity, and substrate availability differ dramatically between neighboring urban and natural areas. We also found that lizards in urban areas use artificial substrates a large proportion of the time, and that these substrates tend to be broader than substrates in natural forest. Finally, our morphological data showed that lizards in urban areas have longer limbs relative to their body size, as well as more subdigital scales called lamellae, when compared to lizards from nearby forested habitats. This shift in phenotype is exactly in the direction predicted based on habitat differences between our urban and natural study sites, combined with our results on how substrates are being used by lizards in these areas. Findings from a common-garden rearing experiment using individuals from one of our three pairs of populations provide evidence that trait differences between urban and natural sites may be genetically based. Taken together, our data suggest that anoles in urban areas are under significant differential natural selection and may be evolutionarily adapting to their human-modified environments.

Effects of Tree Invasion on the Habitat Use of Sand Lizards

The introduction of exotic tree species may interfere with conservation efforts for natural habitats, including grasslands in coastal sand dunes. Natural plant cover is used by several species in coastal dunes of Buenos Aires, Argentina, among them the lizard Liolaemus wiegmannii. Here we study the habitat use and abundance of this lizard inhabiting a psammophytic grassland within this ecosystem, where Acacia longifolia was recently introduced. Surveys and lizard sampling were conducted along 40 transects distributed in four independent zones of 75 ha, each with a different degree of invasion impact. We measured structural and thermal features in relation to A. longifolia and native plants. The lizard L. wiegmannii was three times more abundant in zones with ≤ 25% coverage of A. longifolia. The Jacobs selectivity index showed that all age classes selected native shrubs and avoided A. longifolia trees. These results were similar in greenhouse experiments. However, we found no differences in the use of any of these plants' (introduced or native) leaf litter. Structural and thermal characteristics of the habitat under the shrubs seemed to be more favorable for the physiological performance and behavior of L. wiegmannii, whereas the lower temperatures under A. longifolia might explain the lower presence of lizards in areas where this tree was introduced.

Infra-red irradiance and set point temperatures in behaviourally thermoregulating lacertid lizards

1. 1. Set point temperatures at which Podarcis muralis and Lacerta vivipara ceased basking ( T move; upper set point) and commenced basking ( T bask; lower set point) increased incrementally with increasing i.r. irradiance; values for all set point temperatures were higher in the former species. 2. 2. Changing the i.r. irradiance during a bask resulted in a shift in the upper set point temperature to a level intermediate between the values expected at constant previous and new irradiances (experiment with L. vivipara only). 3. 3. The changes in set-point temperatures following changes in i.r. irradiance were not due to changes in light intensity. 4. 4. The ability to respond to immediate changes in i.r. irradiance is adaptive for lizards in areas in which rapid changes in amounts of sunshine are a feature of the climate.

Artificial egg-laying sites for lizards: A conservation strategy

This paper reports the development of a new technique that may help to increase the number of lizards in areas where scarcity of oviposition sites constitutes the major limiting factor. We have created artificial egg-laying sites for the endangered subspecies of lizard Podarcis hispanica atrata in the Columbretes archipelago. Our results demonstrate that such artificial sites were quickly accepted by the lizards as areas for basking and burrowing. Only one container was used for oviposition by one female, but the physical conditions in the artificial sites allowed successful development in 83% of the eggs which were experimentally placed in them. Additional studies will be required to improve this technique and to determine if it might be applicable to other lizard species.

Sporogony and Experimental Transmission of Plasmodium mexicanum

Plasmodium mexicanum oocysts developed on the stomach wall of Lutzomyia vexatrix occidentis. Pigment was visible in the oocysts until obscured by sporulation. Sporoblasts formed as islands in the oocyst. Sporozoites were routinely obtained from the hemocoel and produced infection in laboratoryreared lizards. In one laboratory-infected lizard, peak schizogony occurred in the late evening at a 4to 5-day interval. This article describes the sporogony of Plasmodium mexicanum and the experimental transfer of infection to laboratory-reared lizards with sporozoites from Lutzomyia vexatrix occidentis (Fig. 1). Phlebotomine sandflies are apparently the natural vectors of lizard malaria in California. The three known species of California sandflies breed in ground squirrel burrows and feed on a variety of cold-blooded vertebrates (Chaniotis and Anderson, 1968). Western fence lizards, Sceloporus occidentalis, commonly use the rodent burrows as refuges. Lizards in areas where sandflies occur are frequently infected with malaria (Ayala, 1970a; Jordan, 1970). The complete extrinsic cycle of P. mexicanum was followed in two species of sandflies: L. v. occidentis and L. stewarti (Ayala and Lee, 1970). MATERIALS AND METHODS The difficulty and effort required to raise sandflies in the laboratory has been cited by numerous workers (e.g., Hertig, 1964). Only wild L. v. occidentis were used in these studies. They were collected from the Twin Sisters Recreation Ranch, Solano County, where surveys indicated that lizard malaria did not occur (Ayala, 1970b). Collection methods using battery-powered light traps and burrow funnel traps were described by Chaniotis and Anderson (1968). In the laboratory, the sandflies were lightly anesthetized with carbon dioxide and transferred to wooden boxes containing clay pots of water covered with fine-mesh cloth screen. The flies were maintained at room temperature (24 to 26 C) or in chambers under controlled temperature and Received for publication 5 November 1970. *Current address: Departamento de Microbiologia, Facultad de Medicina, Universidad del Valle, Apartado aereo 2188, Call, Colombia, South America. humidity. Good survival was obtained only when the humidity was kept above 75%. Lizards were confined in small wire containers or cricket cages and placed with the flies. After feeding, female sandflies were kept in plastic tubes with a cloth screen top and a bottom layer of plaster of paris. The plaster was kept moist by placing the tubes in shallow trays of water. Rinsing the vials beforehand with Mycostatin? (Squibb & Sons, New York) helped control fungus growth. Fresh strawberries or raisins were placed on the screen top for a food source; if they became moldy they were easily removed without excessively contaminating the tubes. For examination, an insect was dipped in a dilute detergent solution, rinsed, and dissected in sterile cold-blooded Ringer's solution. The intestine was removed posteriorly from the abdomen as described by Chaniotis and Anderson (1968), or anteriorly by severing the terminal abdominal segments and pulling on the head with a fine dissecting needle. After examination under a compound microscope, the entire midgut and sporozoites in the surrounding fluid were taken up in a syringe and inoculated intraperitoneally into experimental lizard hosts. Hatchling lizards were raised from eggs in the laboratory using a modification of the incubation technique described by Zweifel (1961). The eggs were collected shortly after they were laid since thin-shelled reptile eggs soon desiccate in a dry terrarium. They were placed on the surface of a mixture of sterile sand and moist wood shavings in a closed plastic bag. Little further care was required. A light was occasionally directed toward the bag to increase the temperature (otherwise kept at room temperature). The hatchlings emerged 28 to 34 days later and were fed small mcalworms, fruit flies, and termites. Wild yearling lizards were collected on the northern abutment of the Golden Gate Bridge, where sandflies were not found and were assumed not to occur because of the severe terrain. No malaria was found in 24 adult lizards examined from the same site. Donor lizards came from Stark Creek in Riverside County and Calaveras reservoir in Santa Clara County. Lizards were kept in long tin cages (100 by 8 by 40 cm) with a 100-watt light bulb at one end providing a