GENOTYPIC DIVERSITY AND GENE FLOW IN BROODING AND SPAWNING CORALS ALONG THE GREAT BARRIER REEF, AUSTRALIA

GENOTYPIC DIVERSITY AND GENE FLOW IN BROODING AND SPAWNING CORALS ALONG THE GREAT BARRIER REEF,... Abstract Marine organisms exhibit great variation in reproductive modes, larval types, and other life‐history traits that may have major evolutionary consequences. We measured local and regional patterns of genetic variation in corals along Australia's Great Barrier Reef to determine the relative contributions of sexual and asexual reproduction to recruitment and to infer levels of gene flow both locally (among adjacent sites, < 5 km apart) and regionally (among reefs separated by 500–1200 km). We selected five common brooding species (Acropora cuneata, A. palifera, Pocillopora damicornis, Seriatopora hystrix, and Stylophora pistillata) and four broadcast spawners (Acropora hyacinthus, A. cytherea, A. millepora, and A. valida), which encompassed a wide range of larval types and potential dispersal capabilities. We found substantial genotypic diversity at local scales in six of the nine species (four brooders, two spawners). For these six, each local population displayed approximately the levels of multilocus genotypic diversity (Go) expected for outcrossed sexual reproduction (mean values of Go:Ge ranged from 0.85 to 1.02), although consistent single‐locus heterozygous deficits indicate that inbreeding occurs at the scale of whole reefs. The remaining three species, the brooder S. hystrix and the spawners A. valida and A. millepora displayed significantly less multilocus genotypic diversity (Go) than was expected for outcrossed sexual reproduction (Ge) within each of several sites. Acropora valida and A. millepora showed evidence of extensive localized asexual replication: (1) a small number of multilocus (clonal) genotypes were numerically dominant within some sites (Go:Ge values were as low as 0.17 and 0.20): (2) single‐locus genotype frequencies were characterized by both excesses and deficits of heterozygotes (cf. Hardy‐Weinberg expectations), and (3) significant linkage disequilibria occurred. For the brooding S. hystrix Go:Ge values were also low within each of four sites (x̄= 0.48). However, this result most likely reflects the highly restricted dispersal of gametes or larvae, because levels of genetic variation among sites within reefs were extremely high (FSR= 0.28). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Evolution Wiley

GENOTYPIC DIVERSITY AND GENE FLOW IN BROODING AND SPAWNING CORALS ALONG THE GREAT BARRIER REEF, AUSTRALIA

Evolution, Volume 54 (5) – Oct 1, 2000

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Publisher
Wiley
Copyright
Copyright © 2000 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0014-3820
eISSN
1558-5646
DOI
10.1111/j.0014-3820.2000.tb00704.x
Publisher site
See Article on Publisher Site

Abstract

Abstract Marine organisms exhibit great variation in reproductive modes, larval types, and other life‐history traits that may have major evolutionary consequences. We measured local and regional patterns of genetic variation in corals along Australia's Great Barrier Reef to determine the relative contributions of sexual and asexual reproduction to recruitment and to infer levels of gene flow both locally (among adjacent sites, < 5 km apart) and regionally (among reefs separated by 500–1200 km). We selected five common brooding species (Acropora cuneata, A. palifera, Pocillopora damicornis, Seriatopora hystrix, and Stylophora pistillata) and four broadcast spawners (Acropora hyacinthus, A. cytherea, A. millepora, and A. valida), which encompassed a wide range of larval types and potential dispersal capabilities. We found substantial genotypic diversity at local scales in six of the nine species (four brooders, two spawners). For these six, each local population displayed approximately the levels of multilocus genotypic diversity (Go) expected for outcrossed sexual reproduction (mean values of Go:Ge ranged from 0.85 to 1.02), although consistent single‐locus heterozygous deficits indicate that inbreeding occurs at the scale of whole reefs. The remaining three species, the brooder S. hystrix and the spawners A. valida and A. millepora displayed significantly less multilocus genotypic diversity (Go) than was expected for outcrossed sexual reproduction (Ge) within each of several sites. Acropora valida and A. millepora showed evidence of extensive localized asexual replication: (1) a small number of multilocus (clonal) genotypes were numerically dominant within some sites (Go:Ge values were as low as 0.17 and 0.20): (2) single‐locus genotype frequencies were characterized by both excesses and deficits of heterozygotes (cf. Hardy‐Weinberg expectations), and (3) significant linkage disequilibria occurred. For the brooding S. hystrix Go:Ge values were also low within each of four sites (x̄= 0.48). However, this result most likely reflects the highly restricted dispersal of gametes or larvae, because levels of genetic variation among sites within reefs were extremely high (FSR= 0.28).

Journal

EvolutionWiley

Published: Oct 1, 2000

Keywords: ; ; ; ; ;

References

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