Hello everyone,
I was able to obtain access to a small number of publications that some of you may find interesting to read. I have decided to provide an abstract from three of these, since they are short enough to type here. The original files are in PDF format; if you would like a copy of any of these, feel free to email me and I would be more than happy to send them your way!
Enjoy!
***These are meant for private use only, and the standard copyright rules apply. Source: Richland College Library (Databases).
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Intra- and Inter-seasonal Variation in the Socio-Spatial Behavior of Adult Male Collared Lizards, Crotaphytus collaris (Reptilia, Crotaphytidae)
Troy A. Baird, Chris L. Sloan & Dusti K. Timanus
Abstract
When individuals maintain strong inter-seasonal philopatry to the same territories, males may be able to re-establish territory occupancy without intense intra- sexual aggression, and instead spend more time courting females early in the reproductive season. Furthermore, when some males have prior experience defending the same territories, it may be necessary for young males to exhibit higher levels of aggression because they are establishing a territory for the first time. We tested these hypotheses by examining within-season (1992 and 1997) temporal variation in the social behavior of adult male collared lizards of known age and prior territorial experience in a population where inter-season philopatry to territories is high. Contrary to expectations, the frequency of aggression exhibited by males with and without prior territorial experience did not differ. The frequency of intra-sexual aggression was higher in 1992 than in 1997, perhaps because male competitors were more abundant in 1992. Although there was an interactive effect of year, male display and patrol were low at the beginning of the reproductive season in Apr. and May, reached peaks during midseason in June, and then decreased as reproduction ended in July. The size of territories showed a similar pattern, with males defending larger areas in June. Our data support the philopatry hypothesis in that the establishment of territories occurred without high levels of aggression early in the season, perhaps because territory boundaries have been well defined by high rates of patrol and advertisement during the middle of the previous season. Inter-sexual interactions were most frequent in June rather than at the beginning of the reproductive season. Adult females are producing their second clutches and yearling females are producing their first clutches in June. The high rate of inter-sexual encounters in June supports the hypothesis that males allocate more time to courtship when females are receptive because there are more reproductively active females at this time. The temporal pattern of activities in adult Crotaphytus collaris appears to function as a compromise between competing intra- and inter-sexual social demands on males, allowing males to maximize mating opportunities as well as maintain future access to productive ter- ritories.
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Lizard community structure across a grassland –
creosote bush ecotone in the Chihuahuan Desert
Sean B. Menke
Abstract
I investigated the distribution and abundance of lizard species (Aspidoscelis inornatus, Aspidoscelis tesselatus, Aspidoscelis tigris, Aspidoscelis uniparens, Cophosaurus texanus, Crotaphytus collaris, Eumeces obsoletus, Gambelia wislizenii, Holbrookia maculata, Phrynosoma cornutum, Sceloporus magister, and Uta stansburiana) across a desert grassland – creosote bush (Larrea tridentata) ecotone in Dona Ana County, New Mexico. The ecotonal area in the Jornada del Muerto basin has increased dramatically in the past 150 years because of the rapid spread of creosote bush. I asked four related questions: how large and where is the ecotone based on vegetative structure, and do lizard abundance and diversity change across the ecotone? Vegetation data were analyzed using discriminate function analysis to determine the extent of the ecotone. Changes in lizard abundance across the ecotone were analyzed by analysis of variance. During two summers, 677 individual lizards of 9 genera and 12 species were captured. Lizard abundance increased with increasing distance from the ecotone and was similar in grassland and creosote bush habitat. Grasslands had higher species richness than both the creosote bush and ecotone habitats. Grassland sites had greater habitat heterogeneity than did creosote bush sites. No ecotone specialist species were detected, and all common lizard species could be found in each habitat. Three potential explanations for decreased abundance in the ecotone are presented: (1) increased risk of predation, (2) decreased prey abundance, and (3) lack of species-specific microhabitat requisites.
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Testing the Central/ Peripheral Model: Analyses of Microsatellite Variability in the Eastern Collared Lizard (Crotaphytus collaris collaris)
Delbert W. Hutchison
Abstract (partial abstract shown)
Surprisingly few studies have empirically compared genetic variation between central and peripheral populations of vertebrates, even though such populations are considered very important to evolutionary theories of anagenetic and cladogenetic change. This study assesses levels of microsatellite variability within and between populations of eastern collared lizards (Crotaphytus collaris collaris) sampled in three regions: the central part of its range and at the northeastern periphery in the southwestern and northeastern Ozarks. As expected, central populations possessed significantly higher within-population variability than peripheral populations, whereas the two peripheral subregions did not differ significantly from one another…
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Fabián Aguirre
Zookeeper/ Freshwater Aquarist
Department of Herpetology and Freshwater Biology
The Dallas World Aquarium
(214) 720-2224
fabian@dwazoo.com
www.dwazoo.com
