. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 2 3 4lh root (sperm/fil Figure 2. As in Figure I. with empirical data (open circles, solid line) plotted against (•>()'i of empirical sperm concentration. Dashed line: Col- lision raie predicted by the VCCW model (Eq. 1 in the text), using the rate ol loiward progression of sperm swimming through a helix. The model predictions are similar to the data. for L. vurii'xutiis eggs with intact jelly coats in the labora- tory (Fig. 3A). To estimate f3 for eggs without jelly coats, I fitted an estimate of j3,, = and empi
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 2 3 4lh root (sperm/fil Figure 2. As in Figure I. with empirical data (open circles, solid line) plotted against (•>()'i of empirical sperm concentration. Dashed line: Col- lision raie predicted by the VCCW model (Eq. 1 in the text), using the rate ol loiward progression of sperm swimming through a helix. The model predictions are similar to the data. for L. vurii'xutiis eggs with intact jelly coats in the labora- tory (Fig. 3A). To estimate f3 for eggs without jelly coats, I fitted an estimate of j3,, = and empirical fertilization data to Styan's (1998) model. This yielded an estimate of |3 = , and /3/j30 = Again, predictions of fertili- zation success fell within the 95% confidence interval about empirical fertilization rates for L. vuriegatits eggs without jelly coats in the laboratory (Fig. 3B). Discussion Consideration of the helical nature of sperm swimming significantly improves the ability of the VCCW model (and the Styan (1998) model, which is derived from the VCCW model) to predict sperm-egg collisions. Adjusting sperm velocity in fertilization-kinetics models to reflect the rate of helical advance, rather than the absolute speed of sperm in the water, adjusting egg "target size" (<r) to reflect the diameter of the helix, and adjusting sperm concentration to reflect dead sperm in laboratory conditions, all contribute to significant improvements in the accuracy with which sperm- egg collision rates are predicted. An improved understanding of sperm swimming may affect our understanding of sperm viability. In fertilization kinetics models (Vogel el 1982: Styan. 1998). the quan- tity J3//30 is interpreted as the quantity of viable sperm, or as the proportion of colliding sperm that initiate fertilization ("fertilization efficiency": Styan. 1998: Styan and Butler. 2000). Typical estimates of/3/j8,, from laboratory data range from t
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
