Broadcast Spawning and the Population Ecology of Coral Reef Animals
Howard Lasker Principal Investigator
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The literature on marine benthic ecology and evolution has generally ignored fertilization rates as an important factor in the life histories of benthic species, many which are important resource species. These rates have implicitly been assumed to be uniformly high and thus not a terribly significant factor in the establishment of the adult populations. There are now a number of data sets which raise doubts about the validity of that assumption. The research will determine rates of fertilization among natural populations and will explore some of the factors controlling these rates in reef communities. Using the Caribbean gorgonian, Plexaura A, as a model system Drs. Lasker and Coffroth will determine rates of fertilization of eggs released in synchronous spawning events. Plexaura A is clonal and often has skewed ratios of male and female colonies on different reefs. This will enable comparison of rates from reefs which differ in current regime and in the density of male colonies. Using random amplified polymorphic DNA (RAPD) from individual planulae larvae, they will conduct paternity analyses, determine the proportion of fertilizations attributable to specific male clones, and determine the effects of clone size and distribution on fertilization. If rates are low and are affected by factors such as population density, then it will be necessary to incorporate fertilization rates in analyses of benthic population animal dynamics and evolution.