Mating system variation in the hermaphroditic brooding coral, Seriatopora hystrix

Area of Science:

• Marine Biology
• Evolutionary Ecology
• Reproductive Biology

Background:

• Hermaphroditic marine invertebrates can self-fertilize or outcross, potentially leading to mixed-mating systems.
• Such strategies are common in plants but less understood in animals.
• Previous studies on Seriatopora hystrix suggested high inbreeding levels.

Purpose of the Study:

• To investigate the mating system of the brooding coral Seriatopora hystrix.
• To estimate selfing rates using population surveys and progeny-array analysis.
• To determine if S. hystrix employs a mixed-mating strategy.

Main Methods:

• Allozyme markers were used for population surveys on reef slope and reef flat sites.
• Direct estimates of selfing were obtained from progeny-array analysis.
• Inbreeding coefficients (F(IS)) and population differentiation (F(ST), F(HT), F(SH)) were calculated.

Main Results:

• Significant inbreeding was detected within populations (F(IS)=0.48).
• Small but significant genetic differentiation was observed among sites (F(ST)=0.04).
• Direct outcrossing estimates for S. hystrix progeny indicated an intermediate outcrossing rate (t(m)=0.53).

Conclusions:

• The mating system of Seriatopora hystrix is variable, involving both selfing and outcrossing.
• Facultative self-fertilization may be a common reproductive strategy in hermaphroditic marine invertebrates.
• Findings support the hypothesis of mixed-mating systems in this coral species.