Turtles in Minature An Investigation into Hatchling Size Manipulation

Knutzen, M.: Turtles in Minature: An Investigation into Hatchling Size Manipulation

Eggs Of Apalone mutica were assigned to a yolk manipulation treatment(control, sham, 0.5 g removal, or 1.0 g removal) and incubated in moist vermiculite (-150kPa) at about 30.5 C. Three eggs from each of 7 clutches were assigned to each treatment for a total of 84 egg. Hatchlings began to emerge approximately 51 days after oviposition. Hatching success was low among yolk-manipulated eggs (approximately 12%; nonsurviving eggs lacked embryos and signs of fungal infection, suggesting that mortality occurred early in development due to trauma caused by the aspiration procedure. Statistical analyses idicated a porportional relationship between egg mass and hatchling massand between the amount of yolk removed and the subsequent decrease in hatchling mass. Modifying aspiration procedure to improve hatching success would thus prove a valuable technique for experimentally manipulating neonate size. Interestingly, however, swimming and righting performance in the laboratory were unrelated to any measure of bosy size. Stil, the crucial tests of the relationship between body size, performance, behavior, and fitness remain to be investigated in the field.

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