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Influence of Body Size and Population Density on Fertilization Success and Reproductive Output in a Free-Spawning
The Biological Bulletin
|January 7, 2018
Summary
High sea urchin density increases fertilization success, compensating for smaller gamete size. This suggests reproductive output estimates based solely on body size can be misleading.
Area of Science:
- Marine Biology
- Reproductive Ecology
- Echinoderm Research
Background:
- Gamete production correlates with body size, but fertilization success is influenced by population density.
- It is commonly assumed that high population density reduces per capita zygote production due to decreased body size and gamete output.
- This study investigates the reproductive output of the sea urchin Diadema antillarum Philippi under varying population densities.
Purpose of the Study:
- To test the assumption that high population density diminishes per capita zygote production.
- To determine the effect of male spawning and population density on fertilization success in Diadema antillarum.
- To model the relationship between population density, gamete production, and overall zygote production.
Main Methods:
- Field study involving three experiments on the sea urchin Diadema antillarum.
- Experiment 1: Assessed fertilization success at varying distances from a spawning male using eggs in Nitex bags.
- Experiment 2: Measured fertilization rates of released eggs captured at different distances downstream from a sperm source.
- Experiment 3: Examined the impact of male size and population density on fertilization success.
Main Results:
- Fertilization success decreased significantly with increasing distance from the sperm source.
- Population density had a significant effect on fertilization success, while male size did not.
- A model indicated that increased fertilization success at high population densities can offset reduced gamete production.
Conclusions:
- High population density can lead to increased fertilization success, potentially compensating for smaller gamete production.
- Per capita zygote production may be similar between small individuals in high-density populations and large individuals in low-density populations.
- Estimating reproductive output based solely on body size or gamete production can be misleading for sea urchins.
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