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DNA barcodes to study and marine biological invasionsDNA barcodes to study and marine biological invasions
What are marine invasions?
Why are we interested?
What are the challenges?
How can DNA barcodes help?Examples of applications to invasive species
problems.
What are marine invasions?
Why are we interested?
What are the challenges?
How can DNA barcodes help?Examples of applications to invasive species
problems.
Marine Biological InvasionsMarine Biological Invasions
Introduced species
Exotic species
Nonindigenous species
Alien species
Introduced species
Exotic species
Nonindigenous species
Alien species
Marine species established with human assistance outside their native ranges.
Invaders cause ecological and economic harm
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Caulerpa taxifolia
Potamocorbula amurensis
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Carcinus maenas
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.Eriocheir sinensis
Asterias amurensis
Invasions are increasing in frequency
Ruiz et al. 2000
Marine invertebrate invasions in North American waters
Num
ber
of f
irst
repo
rts
N=298
The major modern culprit: ballast water
Why study invasions?Why study invasions?
Basic community ecology and evolutionary biology.
Why are some species good invaders but not others?
Why are some communities more vulnerable or resistant?
How do invaders adapt to new enviroments?
How much biogeography is natural or anthropogenic?
Conservation and economics.For policy-makers: risk of harm.
Understand risks of intentional introductions.
How can we best protect native species?
What are effective management practices?
Basic community ecology and evolutionary biology.
Why are some species good invaders but not others?
Why are some communities more vulnerable or resistant?
How do invaders adapt to new enviroments?
How much biogeography is natural or anthropogenic?
Conservation and economics.For policy-makers: risk of harm.
Understand risks of intentional introductions.
How can we best protect native species?
What are effective management practices?
What are some of the problems in studying invasions that DNA barcodes can solve?
I. Issues of identification of larvae and juveniles.• Invaders arrive as larvae.• Invaders spread as larvae.
II. Issues of biogeography and systematics• Many species are cryptogenic: we don’t know if they
are invaders or not. • Sibling and cryptic species complexes confuse patterns
of invasion
III. Issues of taxonomy: the “simple” problem of identification of adults1. Taxonomic expertise is scarce and overburdened.2. Ecologists and managers lack data.
Without solving these problems, pressing research is hindered
Mechanisms and pathways of invasion Primary sources
Secondary spreadPropagule pressure
Native regionsStepping stones
Community and population dynamicsRelation between diversity, disturbance, prior invasion history and vulnerability.
Management practices and assessmentsEvaluating ballast water management practices; e.g., ballast water exchange.
Early detection and eradication“This looks new? Is it invasive? What should I do?”
I. Identifying larvae of invasive species in plankton(natural or ballast water)
Larvae of most marine invertebrates are undescribed. When descriptions are adequate, identification is slow and laborious.
Using DNA barcodes to identify larvae of introduced mussels in Morro Bay, California
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2001
Target species or genera
Tivela stultorum
Macoma (multiple species)
Protothaca stamineaMytilus galloprovincialis
Cytochrome b sequences discriminate species and contain regions that can be used to design species-specific primers.
1400 PCR products scored after gel electrophoresis.
G9FBG19FA
G13MBG20FAG28FAG26FBG27FA
C10MAC22FAC19FBC3MAC26FBC13FA
C21FBC23FA
MNC33BAMN13BMNC39BMN1A
MN17BMN5AMNC42BBMNC34BBMMN6AMNC45BAMNC40BAMMN4AMIC13A
MS1AMS9AMS10B
PS27APSC25B
PSC23ABPSC24ABPSC28BPSC26ABPSC14AA
SGABMercenaria
SG1AATS4A
PitarCalyptogena
ArcticaTNC47BBTNC8BAMTN2BTN3ATN1ATNC6BAMTN1BATNC47BA
SpisulaC.gigas
10 changes
Mytilus galloprovincialis
Mytilus californianus
Macoma nasuta
Protothacastaminea
Tresus nuttalli
Identified Larvae in May
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station/tide
larvae/m^3
Unknown
Protothaca
Tresus
Macoma
Mytilus
incomplete
sand
Ave
rag
e o
f ava
ilab
le r
epl
ica
tes
Low tide Low tideHigh tide High tide
2000 2001
25-90% of larvae/sample were from an introduced mussel..
Cryptogenic species (modified from Cohen and Carlton 1995):
Species which cannot be reliably identified as native or introduced, frequently considered “cosmopolitan.”
II. Systematic and biogeographic problems
California Department of Fish and Game 2002. Introduced Aquatic Species in California Final Report.
Cryptogenic species
7-20%
Cosmopolitan species could be:
1) A single species, truly cosmopolitan.2) A single species spread by human mediated transport.3) Multiple species erroneously described as a single species.4) Combinations of 2&3
Each scenario has a predicted genetic prediction (gene flow, founder effects, phylogenetic structure)
DNA data can solve the problem of cryptogenic species
Ophiactis savignyi: a pantropical species?
"most common brittlestar in the world"-Clark 1946 in Roy and Sponer 2002.
Western Atlantic
Indo-west Pacific
Eastern Pacific
Pacific haplotypes foundin the Western Atlantic;
Closure ofIsthmus of Panama
500 bp mt-CO1
Genetic data shows multiple, geographically disjunct species“Mytilus edulis”: once considered cosmopolitan.
“Mytilus edulis”
Genetic data shows multiple, geographically separated species“Mytilus edulis”: once considered cosmopolitan.
Invasion of California was unnoticed because a native sibling species was already there.
Next, decline of native mussel was unnoticed because it was replaced.Next, decline of native mussel was unnoticed because it was replaced.
DNA from museum collections from the late 1800’s shows M. trossulus in southern CA
M. galloprovincialis arrived in Southern CA in the 1930's
It has progressively spread northward and replaced M. trossulus
DNA from museum collections from the late 1800’s shows M. trossulus in southern CA
M. galloprovincialis arrived in Southern CA in the 1930's
It has progressively spread northward and replaced M. trossulus
Geller, J.B. 1999.
Braby and Somero 2006
North South
19891817
1983 1900
1980
Carcinus maenas
16S mt-rRNA Geller et al. 1997
Sibling species also mask multiple invasions
Geller et al. 1997
Atlantic haplotype (%)
Mediterranean haplotype (%)
Banyul-Sur-Mer, France 0 100
Naples, Italy 0 100
Rio de Betanzos, Spain 100 0
Cadiz, Spain 100 0
Texel Island and Den Helder, Netherlands 100 0
Isle of Wight, U.K. 100 0
Bodega Harbor, CA, USA 100 0
Mystic, CT, USA 100 0
Capetown, South Africa 92 8
Falmouth, Tasmania 100 0
Tokyo Bay, Japan 33 67
California Department of Fish and Game 2002. Introduced Aquatic Species in California Final Report.
IV. Taxonomic issues: the “simple” job ofIdentifying adults.
~30%
Who is going to identify the samples?
Polychaeta
The future of DNA barcoding for the study of marine invasions.
A complete Census of Marine Life/Barcoding project would include all invaders and all potential invaders.
Targeted DNA barcoding of known invaders and high risk species would provide tools now.
DNA barcoding coupled to innovations in sequence detection can speed identification of new invaders, assist monitoring efforts, and relieve taxonomic experts of repetitive identification requests.
Taxonomic expertise is scarce and experts are overburdened.
Watersipora sp.
Mackie et al. 2005