Honors Program Theses


Open Access Honors Program Thesis

First Advisor

Jeffrey Tamplin


In order to survive, turtle hatchlings must be able to choose optimal thermal locations that promote growth and activity through thermoregulation. In some softshell turtle species, embryonic incubation conditions may influence post-hatching phenotypic characters, such as growth rates and temperature preference. I tested the effect of egg-incubation temperature on growth and thermal preferences of Apalone spinifera hatchlings, from Butler County, Iowa. Eggincubation temperature did not affect growth of 10 juvenile Apalone spinifera (Reptilia: Testudines: Trionychidae). After 5 months, hatchlings incubated at 30°C did not differ in size from the turtles incubated at 25°C. In an aquatic thermal gradient from 14-34°C, egg-incubation temperature affected temperature selection among 10 Apalone spinifera hatchlings. Eggincubation temperature was directly related to selected temperature in 3-5 month-old hatchling Apalone spinifera acclimated to 22°C. Hatchlings incubated at 25°C chose the coldest temperature available (14°C) more frequently than any other temperature available; turtles incubated at 30°C selected the warmest temperature available (34°C) more often than any other temperature. In the gradient tank, turtles from both egg-incubation temperature treatments visited more chambers (4.00 ± 0.2) and relocated (7.56 ± 0.7) more frequently between chambers during single-temperature control tests than during gradient runs. These results indicate that juvenile A. spinifera from Iowa can identify temperature differences and select preferred temperatures within at least a 4°C range. This ability to select temperature within a narrow range is a feature that may affect fitness in Apalone spinifera.

Year of Submission



Department of Biology

University Honors Designation

A thesis submitted in partial fulfillment of the requirements for the designation University Honors


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Date Original


Object Description

1 PDF file (viii, 42 pages)