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Dissertation
Effects of maternal identity and incubation environment on morphological, physiological and behavior traits in snapping turtles
Doctor of Philosophy (Ph.D.), Drexel University
1999
DOI:
https://doi.org/10.17918/00009914
Abstract
Several factors can affect offspring phenotype, including maternal effects, developmental conditions, and genetic effects. I examined the contribution of maternal effects, egg incubation temperature, and clutch identity to variation in hatching success, hatching body size, growth, standard metabolic rate, and righting response of the snapping turtle, Chelydra serpentina. Mass at hatching was correlated with egg mass. Both clutch identity and egg incubation temperature affected hatching success and size at hatching. Growth rates varied significantly among clutches, ranging from 5.76 mg d⁻¹ to 9.20 mg d⁻¹. Egg size and mass at hatching were negatively correlated with growth rate, but mass at hatching was positively correlated with individual mass at 175 d. In contrast to results from previous studies, incubation temperature had no significant effects on individual growth. I measured standard metabolic rate at 15°C and 25°C. Mass at hatching, individual mass, and egg mass had no significant effects on metabolic rate at 15°C, but did at 25°C. Incubation temperature had no significant effect on metabolic rate at 15°C, but did at 25°C. Clutch identity had a significant effect on metabolic rate at both 15°C and 25°C. Inter-individual variation in standard metabolic rate due to incubation temperature, and especially clutch identity, could have large effects on energetic considerations. Clutch identity had a significant effect on righting response times in both 1996 and 1997, while egg incubation temperature had no significant effect on righting response time in either 1996 or 1997. Righting response time was consistent and repeatable across individuals and clutches. Results suggest that maternal effects (egg mass) can have significant effects long into ontogeny, because effects of egg size on individual mass were still detectable at 6 months of age. Incubation temperature has effects on some individual traits. Because all individuals received similar treatments and were in similar environments, results suggest that there is a genetic component to growth rate, and both an environmental effect and a genetic effect on standard metabolic rate. Clutch identity had significant effects on all traits examined, and should be considered in future studies as a potential source for phenotypic variation.
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Details
- Title
- Effects of maternal identity and incubation environment on morphological, physiological and behavior traits in snapping turtles
- Creators
- Anthony Cecil Steyermark
- Contributors
- James Robert Spotila (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xix, 217 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Arts and Sciences; Drexel University
- Other Identifier
- 991021888988604721