Effect of Fire and Fragmentation on Aspects of Reproductive Success in Hesperoyucca whipplei.

Abstract

H. whipplei is involved in an obligate association with Tegeticula maculata , the yucca moth. This is the sole pollinator of H. whipplei. Following pollination, the moth deposits an egg in the ovary of the plant, thus ensuring the development of fruit and food for its young. The yucca is native to Southern California, an area where fire is a natural occurrence, and fragmentation of plant populations is rampant. Nevertheless, the effects of these two forces have not been studied. We investigated the effects of these two processes on two aspects of reproductive success, fruit set and number of seeds per fruit. Our preliminary results suggest that fire decreases the number of fruits per plant, but increases the number of seeds per fruit. Smaller fragments seem to produce more fruits per plant, but fragment size appears to have no effect on number of seeds. Although these results are statistically significant, more sites must be analyzed to provide any definite results.