DNA Barcoding - Copy

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Ecole nationale supérieure des sciences de la mer et de l’aménagement du littoral
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• INTRODUCTION
• METHODOLOGY
• RESULTS
• MOLECULAR
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TRADITIONALLY, MORPHOLOGY WAS A KEY FACTOR IN DESCRIBING AND NAMING SPECIES
WITHIN THE FIELD OF TAXONOMY.
NEW APPROACHES BASED ON MOLECULAR MARKERS MIGHT BE OF GREAT HELP IN ADVANCING
OUR KNOWLEDGE OF BIODIVERSITY.
ONE OF THEM IS
DNA BARCODING, WHICH IS CONSIDERED TO PLAY A BIG PART FOR THE FUTURE
STATUS OF TAXONOMY.
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FOR THE RESEARCH, ADRIANA E. RADULOVICI, FRANCE DUFRESNE & PHILIPE ARCHAMBAULT USED
KEY WORDS
ON THE SCIENCE-WEB.
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THEY FIRST DISCOVERED THE GREAT LACK OF ARTICLES ON BIODIVERSITY IN GENERAL.
THEN, THAT THE NUMBER
OF MARINE BIODIVERSITY RESEARCHES ARE CLOSE TO NOTHING IN
COMPARISON TO RESEARCHES IN CONTINENTAL BIODIVERSITY.
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They then proceeded to mix “DNA barcode” and “marine” as keywords and found that the
number of publications treating DNA barcodes boom each year.
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Still the number of publications treating DNA barcodes and marine sciences is weak.
Molecular methods for species Diversity
The use of DNA barcodes consists in extracting and sequencing DNA from a specie’s cell.
In most cases, mitochondrial DNA is used for it’s many benefits such as:
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High evolutionary rate.
Lack of introns.
Large copy numbers in the many mitochondria in each cell.
Limited recombination.
Other methods with other compounds are used:
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Alloenzymes
Glucose phosphate isomerase
Genetic analyses (heterozygosity, allele frequency, private alleles, isolation)
Protein based approaches
Hybridations
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THE USE OF DNA BARCODES BRINGS MANY PROS AND CONS
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• CONTAMINATION WITH
PRIMERS
& PSEUDOGENES.
• MITOCHONDRIAL INTROGRESSION.
• INCOMPLETE
SAMPLING OF TAXA.
• VARIABLE UNPREDICTABLE
MUTATION RATE ACROSS TAXA.
• THE FUNCTIONAL GROUP OF MANY ORGANISMS IS IMPOSSIBLE TO IDENTIFY USING DNA-BARCODES.
• EXPENSIVE FRESH MATERIAL & INCAPACITY OF USING OLD SAMPLES.
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• DISCOVER ISOLATED GROUPS
AND NEW SPECIES.
• ABILITY TO IDENTIFY SPECIMENS DURING ALL LIFE STAGES.
• NON-SPECIALISTS ARE ABLE TO HAVE A FAST, CHEAP AND RELIABLE IDENTIFICATION TOOL.
• SPOTTING
MUTATIONS.
• IDENTIFY INVASIVE SPECIES FROM NATIVE ONES.
• OPEN ACCESS DATA.
• BARCODING PROVIDE PHYLOGENETIC DIVERSITY ANALYSIS THAT WILL BE POINTING AT THE ECOLOGIC
IMPLICATIONS.
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MORPHOLOGICAL IDENTIFICATION CAN SOMETIMES BE IMPOSSIBLE OR MISLEADING WHEN TWO
SPECIES LOOK THE SAME.
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Fisheries management
Identify invasive species
Fish trade regulation
Foot safety
Marine sciences
& taxonomy
Illegal fishing regulation
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Marine algae are one of the simplest
group morphologically
speaking, but due to low
substitution rate in mtDNA, plant
barcoding had a lower
success rate compared to animal kingdom
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THE MOST IMPORTANT COMPONENT
OF CORAL REEFS, CNIDARIANS AND SPONGES
ARE BARCODED USING THEIR
16S GENOMES.
SPONGES ARE THE ONLY INVERTEBRATE
GROUP THAT
ARE BARCODED THROUGH A GLOBAL CAMPAIGN.
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DNA BARCODING DATABASES FACES SOME TROUBLE
DUE TO SPECIES SLIGHT DIVERGENCES AND
INCOMPLETE OR OVERSAMPLING.
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FISHES ARE THE MOST STUDIED MARINE GROUPS,
DNA BARCODE DISCRIMINATED MARINE FISHES
WITH
98% OF SUCCESS.
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BIRDS HAVING INTERACTIONS WITH
THE MARINE
ENVIRONMENT ARE BEING BARCODED WITHIN A
LARGE
‘ALL BIRDS BARCODING INITIATIVE’ PROJECT.
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MANY OTHER GROUPS SUCH AS ECHINODERMS, CRUSTACEANS AND MARINE REPTILES ARE BEING
BARCODED.
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NEW METHODS FOR SAMPLING ALL KIND OF ENVIRONMENT
WELL LEAD TO THE DISCOVERY OF
NEW SPECIES AND UNDERSTUDIED GROUPS WILL BE BETTER MANAGED ONE REFERENCE LIBRARIES
ARE COMPLETED, WITH THE HELP OF NEXT SEQUENCING GENERATIONS.
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