Date Thesis Awarded
Honors Thesis -- Open Access
Bachelors of Science (BS)
For broadcast spawning organisms like echinoderms, the timing of the union of gametes is essential for successful fertilization. However, the release of gametes is not always synchronous and the success of fertilization is highly dependent upon a number of factors including: the number and distribution of spawning adults, the timing of gamete release, the dispersal of gametes, the interaction of gametes within the water column, turbulence in the water column, and the phenotypic properties (e.g. size) of the gametes themselves. Previous studies have shown that the longer sperm is in the water column the greater their mobility decreases and they become diluted, causing fertilization to be less likely. However, the importance of egg age at fertilization has largely been unstudied. Prior research has focused on the presence of a fertilization envelope as a marker of successful development, however, the presence of a fertilization envelope alone does not necessarily indicate whether the fertilized zygote will develop into a normal larva and therefore may be a misleading indicator of successful development. I tested the effects of oocyte age on fertilization success, larval development and metamorphosis to the juvenile stage. My results suggest that oocyte age impacts more than just fertilization rates. Oocytes that are fertilized at a later time point are less likely to survive to the bipinnaria stage of larval development. However, if oocytes survive to become bipinnaria they have an equally likely chance of metamorphosing into a juvenile. My work suggests that researchers should carefully monitor gamete maturation and release in asteroid echinoderms, and likely other marine invertebrates, to avoid artifacts of gamete age on experiments with marine invertebrate eggs, embryos and larvae.
Yeo, Amanda, "Effects of Gamete Age on Development in Asterias forbesi" (2021). Undergraduate Honors Theses. William & Mary. Paper 1655.