Title

To conform or regulate, are these the only options? Thermal Biology of the Mexican beaded lizard (Heloderma horridum horridum) in a tropical deciduous forest

Presenter Information

Kerry Holcomb

Document Type

Oral Presentation

Location

SURC 201

Start Date

17-5-2012

End Date

17-5-2012

Abstract

By shuttling between cool and warm patches in their habitat, reptiles can maintain stable as well as suitable body temperatures�"this is known as active thermoregulation. Nevertheless, active thermoregulation is physically challenging and behaviorally expensive for medium to large reptiles (>500g). We contrasted Mexican Beaded lizard body temperature management between the wet and dry seasons, in a tropical deciduous forest, near Chamela, Jalisco, Mexico. Animals were tracked using radiotelemetry and monitored for habitat use patterns and behavior. Implanted Thermocron ibuttonTM temperature dataloggers were used to record body temperatures at 15 minute intervals (n = 6 lizards). Body temperatures of active beaded lizards were found to correlate strongly with concurrent ambient temperature, in both the dry and wet seasons, indicating a conformist strategy to thermal management. Yet, shelters occupied by beaded lizards showed ambient temperatures close to this species preferred body temperature. Thermal selectivity in refuge choice, as well as temporal patterns of refuge use, enabled beaded lizards to regulate body temperature tightly. For instance, 54.4 percent of dry-season and 30.4 percent of wet-season body temperatures fell between 27.1 and 29.9˚C, which agrees with this species preferred body temperature�" 27.5 to 31.25 ˚C (n=5 lizards). Rather than actively thermoregulate, beaded lizards seem to manage body temperature through careful refuge selection and activity scheduling. Furthermore, homeothermy achieved using this strategy can be held for many days, a level of thermal stability that is impossible to maintain through active behavioral thermoregulation.

Faculty Mentor(s)

Dan Beck

Additional Mentoring Department

Biological Sciences

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May 17th, 3:00 PM May 17th, 3:20 PM

To conform or regulate, are these the only options? Thermal Biology of the Mexican beaded lizard (Heloderma horridum horridum) in a tropical deciduous forest

SURC 201

By shuttling between cool and warm patches in their habitat, reptiles can maintain stable as well as suitable body temperatures�"this is known as active thermoregulation. Nevertheless, active thermoregulation is physically challenging and behaviorally expensive for medium to large reptiles (>500g). We contrasted Mexican Beaded lizard body temperature management between the wet and dry seasons, in a tropical deciduous forest, near Chamela, Jalisco, Mexico. Animals were tracked using radiotelemetry and monitored for habitat use patterns and behavior. Implanted Thermocron ibuttonTM temperature dataloggers were used to record body temperatures at 15 minute intervals (n = 6 lizards). Body temperatures of active beaded lizards were found to correlate strongly with concurrent ambient temperature, in both the dry and wet seasons, indicating a conformist strategy to thermal management. Yet, shelters occupied by beaded lizards showed ambient temperatures close to this species preferred body temperature. Thermal selectivity in refuge choice, as well as temporal patterns of refuge use, enabled beaded lizards to regulate body temperature tightly. For instance, 54.4 percent of dry-season and 30.4 percent of wet-season body temperatures fell between 27.1 and 29.9˚C, which agrees with this species preferred body temperature�" 27.5 to 31.25 ˚C (n=5 lizards). Rather than actively thermoregulate, beaded lizards seem to manage body temperature through careful refuge selection and activity scheduling. Furthermore, homeothermy achieved using this strategy can be held for many days, a level of thermal stability that is impossible to maintain through active behavioral thermoregulation.