Reproductive Investment Patterns in a Captive Population of Alligator Snapping Turtles (Macrochelys temminckii)


Identifying resource allocation patterns is fundamental to understanding reproductive investment strategies that maximize maternal fitness. Turtles are useful model organisms for such studies because many species do not invest in postnesting parental care; therefore, variation in maternal investment can be assessed primarily from variation in clutch characteristics. We examined maternal investment patterns in Macrochelys temminckii by measuring reproductive output of captive turtles exposed to similar conditions. Larger females tended to produce larger eggs by mass, but not diameter, and female size and within-clutch variation accounted for 68% of the total variation in egg size. The number of eggs per clutch did not correlate with female body size. Larger females exhibited greater total reproductive effort, however, because total clutch mass positively correlated with female size. Hatchling size increased with increasing egg size, but there was no relationship between female size and hatchling size. There was an effect of female identity on hatchling size independent of female size. Female body condition did not explain any of the variation in clutch, egg, or hatchling characteristics. Clutch size varied more than egg size and, after controlling for female size, we also found evidence of a negative correlation between clutch and egg size. These results indicate that M. temminckii primarily increase maternal investment by producing more eggs rather than bigger eggs. Finally, resource availability affected the number of eggs females produced, but the size of individual eggs might be more influenced by factors related to maternal identity.



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Chelydridae, Maternal investment, Optimal egg size, Parental investment, Resource allocation

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