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First published online May 21, 2007
Journal of Experimental Biology 210, 1859-1867 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.001875
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Use of portable ultrasonography as a nondestructive method for estimating reproductive effort in lizards

Casey A. Gilman* and Blair O. Wolf

University of New Mexico, Department of Biology, MSC03-2020, 1 University of New Mexico, Albuquerque, NM 87131-0001, USA


Figure 1
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Fig. 1. Transverse scan of one female A. tesselata. Dense tissues (skin, bone, egg shell) appear lighter (echogenic) on the scan. This individual was observed to have two large, shelled eggs (e) and a single vitellogenic follicle (f) located between them, close to the ventral surface. Virtual calipers (dotted white line) show the height of one of the eggs (height in cm is shown to the bottom left of the image).

 

Figure 2
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Fig. 2. Relationships between ultrasound-estimated values and actual values determined from dissection for (A) clutch size, (B) average egg volume and (C) clutch volume. Each graph shows values for all individuals (N=42). The dotted lines indicate the isometric reference and the solid lines represent the regression equations fit to the data. Act., actual value; U.S., ultrasound estimate.

 

Figure 3
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Fig. 3. Changes in average egg volume for each clutch throughout the duration of the study. Data shown are for one H. maculata (Homa1) and two U. stansburiana (Utst431 and Utst451), all of whom had clutches that progressed from small follicles to shelled eggs, and two C. collaris (Crco1 and Crco2), whose follicles increased in volume initially but then decreased prior to ovulation. Lines are fit solely to illustrate the trends.

 

Figure 4
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Fig. 4. Sagittal scan of one P. hernandesi female, showing partial skeletons of at least five well-developed embryos. This scan was made 42 days after the initial scan and 12 days before the young were born.

 

Figure 5
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Fig. 5. Transverse scan of one P. cornutum female, showing five shelled eggs. Notice the asymmetry of the eggs caused by egg overlap and compression. Virtual calipers (dotted white lines) show the width of egg 4. Scan is focused on one side of the animal because the animal's width exceeded that of the transducer, as was the case in all individuals of P. cornutum.

 





© The Company of Biologists Ltd 2007