title: Genetic differentiation and connectivity of morphological types of the broadcast-spawning coral Galaxea fascicularis in the Nansei Islands, Japan.
abstract: Population connectivity resulting from larval dispersal is essential for the maintenance or recovery of populations in marine ecosystems, including coral reefs. Studies of species diversity and genetic connectivity within species are essential for the conservation of corals and coral reef ecosystems. We analyzed mitochondrial DNA sequence types and microsatellite genotypes of the broadcast-spawning coral, Galaxea fascicularis, from four regions in the subtropical Nansei Islands in the northwestern Pacific Ocean. Two types (soft and hard types) of nematocyst morphology are known in G. fascicularis and are significantly correlated with the length of a mitochondrial DNA noncoding sequence (soft type: mt-L; hard type: mt-S type). Using microsatellites, significant genetic differentiation was detected between the mitochondrial DNA sequence types in all regions. We also found a third genetic cluster (mt-L+), and this unexpected type may be a cryptic species of Galaxea. High clonal diversity was detected in both mt-L and mt-S types. Significant genetic differentiation, which was found among regions within a given type (F ST = 0.009-0.024, all Ps ≤ 0.005 in mt-L; 0.009-0.032, all Ps ≤ 0.01 in mt-S), may result from the shorter larval development than in other broadcast-spawning corals, such as the genus Acropora. Nevertheless, intraspecific genetic diversity and connectivity have been maintained, and with both sexual and asexual reproduction, this species appears to have a potential for the recovery of populations after disturbance.
authors.affiliation: Marine Biophysics Unit Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha Onna Okinawa 904-0495 Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Nakajima
authors.affiliation: Marine Genomics Unit Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha Onna Okinawa 904-0495 Japan.
authors.forename: Yuna
authors.initials: Y
authors.lastname: Zayasu
authors.affiliation: Marine Genomics Unit Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha Onna Okinawa 904-0495 Japan.
authors.forename: Chuya
authors.initials: C
authors.lastname: Shinzato
authors.affiliation: Marine Genomics Unit Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha Onna Okinawa 904-0495 Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Satoh
authors.affiliation: Marine Biophysics Unit Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha Onna Okinawa 904-0495 Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mitarai
keywords: Conservation; cryptic species; genetic diversity; microsatellite; population genetics