Reduction in Locomotor Ability as a Cost of Reproduction in Gravid Snakes

• Published in: Oecologia Vol. 73; no. 4; pp. 481 - 485
• Main Authors: Seigel, R. A., M. M. Huggins, Ford, N. B.
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01-10-1987; Springer
• Subjects: Animal reproduction; Average linear density; Biological and medical sciences; Endurance; Female animals; Foraging; Fundamental and applied biological sciences. Psychology; Garters; Lizards; Pregnancy; Reproductive traits; Snakes; Thamnophis marcianus; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Pregnancy; Locomotion; Vertebrata; United States; Texas; America; Female; Reptilia; North America; Ophidia; Life history; Costs of reproduction; Locomotor ability; Snakes
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/BF00379404

Recent studies suggest that lower survival among gravid squamate reptiles may be partially the result of decreased locomotor ability during gestation. In this study, we compared the speed and endurance of female garter snakes (Thamnophis marcianus) before, during, and after pregnancy. Gravid snakes had significantly lower locomotor performance than did non-gravid females, and performance varied among stages of gestation, reaching a minimum 0-6 weeks prior to parturition. Both number of offspring and relative clutch mass were inversely correlated with locomotor performance; as females increased these traits, locomotor ability decreased. If reduced locomotor performance results in greater risk of predation and/or lowered foraging ability, then natural selection (operating via differential mortality or feeding rates of gravid females) may result in important constraints on both clutch size and relative clutch mass in squamates.