Geographic patterns of genetic variation in a broadly distributed marine vertebrate: new insights into loggerhead turtle stock structure from expanded mitochondrial DNA sequences.
Previous genetic studies have demonstrated that natal homing shapes the stock structure of marine turtle nesting populations. However, widespread sharing of common haplotypes based on short segments of the mitochondrial control region often limits resolution of the demographic connectivity of populations. Recent studies employing longer control region sequences to resolve haplotype sharing have focused on regional assessments of genetic structure and phylogeography. Here we synthesize available control region sequences for loggerhead turtles from the Mediterranean Sea, Atlantic, and western Indian Ocean basins. These data represent six of the nine globally significant regional management units (RMUs) for the species and include novel sequence data from Brazil, Cape Verde, South Africa and Oman. Genetic tests of differentiation among 42 rookeries represented by short sequences (380 bp haplotypes from 3,486 samples) and 40 rookeries represented by long sequences (∼800 bp haplotypes from 3,434 samples) supported the distinction of the six RMUs analyzed as well as recognition of at least 18 demographically independent management units (MUs) with respect to female natal homing. A total of 59 haplotypes were resolved. These haplotypes belonged to two highly divergent global lineages, with haplogroup I represented primarily by CC-A1, CC-A4, and CC-A11 variants and haplogroup II represented by CC-A2 and derived variants. Geographic distribution patterns of haplogroup II haplotypes and the nested position of CC-A11.6 from Oman among the Atlantic haplotypes invoke recent colonization of the Indian Ocean from the Atlantic for both global lineages. The haplotypes we confirmed for western Indian Ocean RMUs allow reinterpretation of previous mixed stock analysis and further suggest that contemporary migratory connectivity between the Indian and Atlantic Oceans occurs on a broader scale than previously hypothesized. This study represents a valuable model for conducting comprehensive international cooperative data management and research in marine ecology.
National Research Council Research Associateship Program, Washington, D.C., United States of America ; Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Atmospheric and Oceanic Administration Fisheries, La Jolla, California, United States of America.
Brian M
BM
Shamblin
Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, Gainesville, Florida, United States of America.
Alan B
AB
Bolten
Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mazatlán, Sinaloa, México.
F Alberto
FA
Abreu-Grobois
Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, Gainesville, Florida, United States of America.
Karen A
KA
Bjorndal
Department of Animal Biology and IRBio, Faculty of Biology, University of Barcelona, Barcelona, Spain.
Luis
L
Cardona
Department of Animal Biology and IRBio, Faculty of Biology, University of Barcelona, Barcelona, Spain ; Marine Turtle Research Group, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Peryn, Cornwall, United Kingdom.
Carlos
C
Carreras
Department of Animal Biology and IRBio, Faculty of Biology, University of Barcelona, Barcelona, Spain.
Marcel
M
Clusa
Departamento de Biología, Universidad de Las Palmas de Gran Canaria, Campus de Tafira, Las Palmas de Gran Canaria, Spain.
Catalina
C
Monzón-Argüello
Daniel B. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, United States of America.
Campbell J
CJ
Nairn
Department of Biology, University of Miami, Coral Gables, Florida, United States of America.
Janne T
JT
Nielsen
Zoology Department, Nelson Mandela Metropolitan University, Summerstrand Campus South, University Way, Summerstrand, Port Elizabeth, South Africa.
Ronel
R
Nel
Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, Gainesville, Florida, United States of America ; Projeto TAMAR-ICMBio, Salvador, BA, Brazil.
Luciano S
LS
Soares
Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Atmospheric and Oceanic Administration Fisheries, La Jolla, California, United States of America ; The Ocean Foundation, Washington, D.C., United States of America.
Kelly R
KR
Stewart
Laboratório de Biodiversidade e Evolução Molecular, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Sibelle T
ST
Vilaça
Adnan Menderes University, Faculty of Science and Arts, Department of Biology, Aydin, Turkey.
Oguz
O
Türkozan
Adnan Menderes University, Faculty of Science and Arts, Department of Biology, Aydin, Turkey.
Can
C
Yilmaz
Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Atmospheric and Oceanic Administration Fisheries, La Jolla, California, United States of America.
Peter H
PH
Dutton
D000818:Animals; D001267:Atlantic Ocean; D003247:Conservation of Natural Resources; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D005828:Genetics, Population; D006239:Haplotypes; D019156:Indian Ocean; D008522:Mediterranean Sea; D008928:Mitochondria / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D017422:Sequence Analysis, DNA; D014426:Turtles / Q000235:genetics*
D004272:DNA, Mitochondrial