Phenotypic Consequences of Gestation Temperature in the Northern Watersnake, Nerodia Sipedon

Temperature during embryonic development can strongly influence the developmental trajectory of reptiles. In snakes, offspring morphology, locomotor speed, anti-predator behavior, and growth are known to be affected by developmental temperature and are likely to have important fitness consequences. I explored the influence of gestation temperature on offspring phenotypes produced by gravid Northern Watersnakes (Nerodia sipedon) maintained at constant temperatures of 23, 26, and 29°;C. Swimming speed, defensive strikes, and flight response were tested at 1 and 26 weeks of age, and growth was measured until 30 weeks of age. The number of ventral scale rows was higher in snakes from the 26°;C group than from the 29°;C group. Thermal influences were persistent over time across temperature treatments. Snakes from the 23°;C treatment swam slower at both testing ages, exhibited lower defensive behavior scores at 1 week of age, and exhibited lower embryonic survival than snakes from the other treatments. Growth in body length, head length, and head width for snakes from 23°;C was higher than for other treatments, but was possibly influenced by feeding regime. The results of my study are consistent with embryonic thermal sensitivity in other reptile taxa in suggesting that thermoregulatory precision by gravid female N. sipedon affects fecundity and measures of performance that likely influence offspring survival.

Name thesis:degree_name

Master of Science in Biology

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Biology

Year

2014

Author dc:creator

• Wrensch, Zachary Charles

Contributors dc:contributor

• Brian Greene

• Nerodia sipedon
• gestation temperature
• phenotype
• performance
• viviparity
• Biology

Statement dc:rights

• © Zachary Charles Wrensch

Repository record dc:identifier

https://bearworks.missouristate.edu/theses/1328

OAI identifier oai:identifier

oai:bearworks.missouristate.edu:theses-2329