Title

Design and sediment characteristics of Mexican Beaded Lizard Burrows in Jalisco, Mexico

Document Type

Oral Presentation

Location

SURC Ballroom A

Start Date

17-5-2012

End Date

17-5-2012

Abstract

A diverse group of vertebrates and invertebrates insulate themselves in subterranean refuges from variability and extremes found in above ground environments. However, little is known about the design of these burrows or the geological characteristics of the sediments into which they are excavated. Geological and design characteristics of Mexican beaded lizard wet and dry season burrows were compared at a field site near Chamela, Jalisco, Mexico. We assessed two hypotheses: 1) Ectothermic vertebrates are selective when choosing refuge sites; and 2) Ectothermic vertebrates choose particular burrow designs depending on season. At 10 sites previously used by beaded lizards we collected sediment samples at the surface, 20cm, and 75cm depths. At 8 of these sites the previously or currently occupied burrow was located and excavated to examine the design of the burrow and to sample the chamber sediment. Sediment samples were analyzed for grain-size distribution, current soil moisture, and water-retention capacity. Burrow site selection was found to be systematic. Percent sediment moisture content was found to be higher at burrow sites as compared with two systematically placed transects. Dry-season burrows were longer, deeper and had a smaller diameter relative to wet-season burrows. Wet-season burrow sediments retained more water and had lower percent gravel content relative to dry-season burrows. These results emphasize the importance of certain burrow characteristics to the seasonal survival of beaded lizards and possibly other ectothermic vertebrates

Poster Number

3

Faculty Mentor(s)

Lisa Eily, Dan Beck

Additional Mentoring Department

Geological Sciences

Additional Mentoring Department

Biological Sciences

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May 17th, 8:30 AM May 17th, 11:00 AM

Design and sediment characteristics of Mexican Beaded Lizard Burrows in Jalisco, Mexico

SURC Ballroom A

A diverse group of vertebrates and invertebrates insulate themselves in subterranean refuges from variability and extremes found in above ground environments. However, little is known about the design of these burrows or the geological characteristics of the sediments into which they are excavated. Geological and design characteristics of Mexican beaded lizard wet and dry season burrows were compared at a field site near Chamela, Jalisco, Mexico. We assessed two hypotheses: 1) Ectothermic vertebrates are selective when choosing refuge sites; and 2) Ectothermic vertebrates choose particular burrow designs depending on season. At 10 sites previously used by beaded lizards we collected sediment samples at the surface, 20cm, and 75cm depths. At 8 of these sites the previously or currently occupied burrow was located and excavated to examine the design of the burrow and to sample the chamber sediment. Sediment samples were analyzed for grain-size distribution, current soil moisture, and water-retention capacity. Burrow site selection was found to be systematic. Percent sediment moisture content was found to be higher at burrow sites as compared with two systematically placed transects. Dry-season burrows were longer, deeper and had a smaller diameter relative to wet-season burrows. Wet-season burrow sediments retained more water and had lower percent gravel content relative to dry-season burrows. These results emphasize the importance of certain burrow characteristics to the seasonal survival of beaded lizards and possibly other ectothermic vertebrates