Document Type

Thesis

Date of Degree Completion

Winter 2021

Degree Name

Master of Science (MS)

Department

Biology

Committee Chair

Daniel Beck

Second Committee Member

Alison Scoville

Third Committee Member

Lixing Sun

Abstract

Mud turtles (family Kinosternidae) are primarily threatened by climate change, overexploitation, and land development. To survive in increasingly urbanized and arid regions, mud turtles often inhabit man-made water sources such as cattle troughs and irrigation ditches. These bodies of water are critical in urban habitat where they may offer some of the last remaining refugia; however, the effect of these conditions on population structure is poorly understood. The Jalisco mud turtle (Kinosternon chimalhuaca) was described in 1997 from a small range south of Puerto Vallarta, Mexico. Since its description, critical ecological research has remained largely nonexistent, hindering effective conservation and management. Recent satellite imagery surrounding our study sites in has shown the loss of lowland deciduous forest and an increase in human activity through deforestation and fragmentation with a dramatic increase in population and tourism. Our research reports the first comparative analysis of K. chimalhuaca’s populations from a pristine forested arroyo habitat in the Chamela-Cuixmala Biosphere Reserve, and a semi-urban habitat in a nearby small town. In July and December of 2019, our team surveyed a small ~1km irrigation ditch in the middle of town and astonishingly captured, marked, and measured 226 turtles, estimating a population of 741 ± 132 individuals. Similar trapping effort in the forest habitat surrounding the Chamela field station yielded 12 turtles, added to a collection of 25 prior opportunistic captures. In town, turtles exhibited a iii female-biased ratio (1:2.16; 68% female; N = 174), contrasting the male-biased forest population (2.63:1; 28% female; N = 29). The carapace length (CL) of forest males was more bimodally distributed and significantly larger (p = 0.036) than their semi-urban counterparts. Forest females were also significantly larger than female turtles from the town (p = 0.012). The findings of this preliminary dataset warrant further investigation into the driving factors supporting abundant semi-urban populations and the effects of human-turtle interactions in the face of global turtle declines.

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