widespread occurrence and genetic diversity of marine...

Widespread occurrence and genetic diversity of marineparasitoids belonging to Syndiniales (Alveolata)

L. Guillou,1* M. Viprey,1 A. Chambouvet,1

R. M. Welsh,2 A. R. Kirkham,3 R. Massana,4

D. J. Scanlan3 and A. Z. Worden21Station Biologique de Roscoff, UMR7144, CNRS etUniversité Pierre et Marie Curie, BP74, 29682 RoscoffCedex, France.2Monterey Bay Aquarium Research Institute, 7700Sandholdt Road, Moss Landing, CA 95039, USA.3Department of Biological Sciences, University ofWarwick, Coventry CV4 7AL, UK.4Institut de Ciències del Mar, CMIMA, Passeig Marítimde la Barceloneta 37-49, 08003 Barcelona, Catalonia,Spain.

Summary

Syndiniales are a parasitic order within the eukaryoticlineage Dinophyceae (Alveolata). Here, we analysedthe taxonomy of this group using 43655 18S rRNAgene sequences obtained either from environmentaldata sets or cultures, including 6874 environmentalsequences from this study derived from Atlantic andMediterranean waters. A total of 5571 out of the 43655sequences analysed fell within the Dinophyceae.Both bayesian and maximum likelihood phylogeniesplaced Syndiniales in five main groups (I–V), as amonophyletic lineage at the base of ‘core’ dinoflagel-lates (all Dinophyceae except Syndiniales), althoughthe latter placement was not bootstrap supported.Thus, the two uncultured novel marine alveolategroups I and II, which have been highlighted previ-ously, are confirmed to belong to the Syndiniales.These groups were the most diverse and highlyrepresented in environmental studies. Within each,8 and 44 clades were identified respectively.Co-evolutionary trends between parasitic Syndinialesand their putative hosts were not clear, suggestingthey may be relatively ‘general’ parasitoids. Based onthe overall distribution patterns of the Syndiniales-affiliated sequences, we propose that Syndiniales areexclusively marine. Interestingly, sequences belong-ing to groups II, III and V were largely retrieved from

the photic zone, while Group I dominated samplesfrom anoxic and suboxic ecosystems. Nevertheless,both groups I and II contained specific clades prefer-entially, or exclusively, retrieved from these latterecosystems. Given the broad distribution of Syndini-ales, our work indicates that parasitism may be amajor force in ocean food webs, a force that isneglected in current conceptualizations of the marinecarbon cycle.

Introduction

The Alveolata, one of the major eukaryotic lineages, iscomposed of four protist classes: the Ciliophora, theApicomplexa, the Perkinsea and the Dinoflagellata.Alveolata have adopted a large range of trophic modesand habitats. They can be important marine primaryproducers. For instance, about half of dinoflagellates arephotosynthetic (Lessard and Swift, 1986), with somebeing responsible for toxic algal blooms. Ciliates anddinoflagellates can also be active predators; others arecoral symbionts (e.g. the dinoflagellate Symbiodiniumspp.) and some ciliates even reside in mammalian guts(Williams and Coleman, 1992). Finally, a large number ofspecies are parasites, broadly distributed throughoutthese Alveolata classes. For instance, Apicomplexa iscomposed solely of obligate parasites. In addition to phy-logenetic relatedness based on gene sequence compari-sons, Alveolata are unified by specific morphologicalcharacters. These include the presence of membrane-bound flattened vesicles, termed alveoli (Cavalier-Smith,1993; Patterson, 1999), distinct pores called microporesthat pierce the outer membrane and the presence of amore or less developed apical complex apparatus usedby alveolate parasites to enter their host (reviewed byLeander and Keeling, 2003).

The discovery of novel marine alveolate (MALV) lin-eages in marine planktonic communities by culture-independent techniques, specifically MALV groups I and II(Díez et al., 2001a; López-García et al., 2001; Moon-vander Staay et al., 2001), has raised questions regardingfunctional roles of these diverse populations. Phyloge-netic analyses showed MALV Group II belongs to theSyndiniales, a dinoflagellate order exclusively composedof marine parasites. This assignment was based on theclose phylogenetic relatedness of the environmental 18S

Received 17 April, 2008; accepted 29 June, 2008. *Forcorrespondence. E-mail [email protected]; Tel. (+33) 2 98 29 2379; Fax (+33) 2 98 29 23 24.

Environmental Microbiology (2008) 10(12), 3349–3365 doi:10.1111/j.1462-2920.2008.01731.x

Journal compilation © 2008 Society for Applied Microbiology and Blackwell Publishing LtdNo claim to original French government works

mailto:[email protected]

rRNA gene sequences (Moon-van der Staay et al., 2001;Skovgaard et al., 2005) with three previously describedgenera: Amoebophrya spp., Hematodinium spp. and Syn-dinium spp. More recently, 18S rRNA gene sequencesderived from Ichthyodinium chaberladi (Gestal et al.,2006) and Duboscquella sp. (Harada et al., 2007), twoparasitic Syndiniales genera, showed an affiliation withMALV Group I.

MALV groups I and II have been retrieved from variousmarine habitats, mainly from the picoplankton fraction (< 2or < 3 mm size fractionated samples). These groups fre-quently form the majority of sequences within marineenvironmental clone libraries (see López-García et al.,2001; Moon-van der Staay et al., 2001; Massana et al.,2004; Romari and Vaulot, 2004; Not et al., 2007). This hasled to a large increase in the number of MALV sequencesdeposited in GenBank over the last few years. In a previ-ous study, Groisillier and colleagues (2006) detected fivedistinct clades within MALV Group I, and 16 clades withinMALV Group II. However, in that study, many sequencescould not be clearly assigned to a specific clade, suggest-ing further discrete lineages might exist. Interestingly,some clades comprised sequences retrieved only fromvery specific habitats, such as anoxic environments ordeep sea hydrothermal vents, while other clades con-tained sequences obtained from widely varying habitats.

In the present work our aims were (i) to broaden repre-sentation of the different environments in which membersof the Alveolata are potentially encountered by construct-ing and sequencing 18S rRNA gene libraries; (ii) to clarifythe phylogeny of the Alveolata using recently publishedand the new 18S rRNA gene sequences for this group; (iii)to undertake a rigorous review of clade organizationwithin the above mentioned MALV groups I and II; (iv)to compare the genetic diversity of environmentalsequences derived from culture-independent PCRsurveys (targeting the 18S rRNA gene) to our presentknowledge of the taxonomy of Syndiniales; and (v) toextract general information on the preferred habitats anddistribution of specific members of the Syndiniales.

Results

Sample sites and environmental conditions

Most of the novel environmental sequences obtained inthis study were retrieved from coastal and oceanic watersin the Atlantic Ocean and Mediterranean Sea (Table 1).The collection sites varied in terms of season, depth andlevel of oligotrophy. For example, the Bermuda AtlanticTime-series Station (BATS) is relatively oligotrophic, andat the time of sampling was already strongly stratified. Incontrast, the northern Sargasso Sea Station, althoughrelatively close to BATS, was likely still influenced by deep

winter mixing that occurs in this area, bringing nutrients tosurface waters (see Cuvelier et al., 2008 for furtherdiscussion). The Florida Straits sites represent three dis-tinct water types. Station 1, on the western side of theFlorida Straits, was relatively coastal. Station 4 representsthe core of the Gulf Stream Current-forming waters, whichare highly oligotrophic, while Station 14 is also olig-otrophic but a shallow setting on the eastern side of theFlorida Straits (see Cuvelier et al., 2008). Other environ-mental sequences from the Atlantic Ocean were obtainedduring the Atlantic Meridional Transect (AMT 15, see alsoZwirglmaier et al., 2007), which extended from 48°N[south-west (SW) of the UK] to 40°S (SW of Cape Town,South Africa). Environmental sequences from the Medi-terranean Sea were collected in late summer along aMediterranean transect sampled during the PROSOPEcruise in 1999 (Garczarek et al., 2007), from high nutrientlevels in the Morocco upwelling to strong phosphoruslimitation in the eastern most basin. Although half of thegenetic libraries were built using a PCR approach biasedtowards green algae, dinoflagellate sequences wereretrieved in both data sets (the majority of them wereretrieved using general eukaryotic primers). We also useda PCR approach biased towards MALV Group II (usingthe specific primer ALV01) that we compared with the useof general eukaryotic primers from a coastal site (EnglishChannel, France). Most of genetic libraries were built onvery small size fractions (less than 2–3 mm), althoughsome were processed on larger size fractions and evenafter incubations (see genetic libraries from coastal sitesfrom the Mediterranean Sea). This heterogeneous dataset offered us a very large range of environmentalsequence origins. In total, 6874 new environmentalsequences were generated and screened for dinoflagel-late sequences.

Alveolate 18S rRNA gene sequence data set

The completed data set comprised 43655 eukaryotic 18SrRNA gene sequences obtained either from GenBank orfrom the environmental clone libraries described above.From marine environments, 351 environmental clonelibraries were analysed with major contribution from sites(Table 2) in the Atlantic (Díez et al., 2001a; Countwayet al., 2007; Not et al., 2007), Indian (Not et al., 2008),Arctic (Lovejoy et al., 2006; Stoeck et al., 2007) andPacific (Moon-van der Staay et al., 2001) Oceans, Medi-terranean Sea (Viprey et al., 2008), Antarctic (López-García et al., 2001), as well as several coastal sites(Massana et al., 2004; Romari and Vaulot, 2004; Medlinet al., 2006; Worden, 2006). These encompassed a rangeof marine habitats including the photic zone, sediments,hydrothermal vents and anoxic ecosystems (Table 2). Ter-restrial and continental ecosystems were also included

3350 L. Guillou et al.

Journal compilation © 2008 Society for Applied Microbiology and Blackwell Publishing Ltd, Environmental Microbiology, 10, 3349–3365No claim to original French government works

Tab

le1.

Des

crip

tion

ofth

esa

mpl

ing

site

san

dch

arac

teris

tics

ofcl

one

libra

ries

cons

truc

ted

for

this

stud

y.

Env

ironm

ent

and

crui

seS

tatio

nan

dS

iteC

oord

inat

esD

ate

Cod

elib

rary

Dep

th(m

)P

rimer

Sam

ple

deta

ils(m

m)

Tota

lnum

ber

ofcl

ones

with

inse

rtsc

reen

ed

Med

iterr

anea

nS

eaP

RO

SO

PE

Oce

anic

euph

otic

zone

Acc

essi

onnu

mbe

rsfr

omE

U79

2921

toE

U79

3941

+E

U84

8494

toE

U84

8495

See

also

Vip

rey

etal

.(2

008)

St

1S

trai

tof

Gib

ralta

r38

°08′

N05

°18′

W14

-Sep

-99

C1-

3030

Euk

328f

-CH

LO02

<3

246

E1-

3030

Euk

328f

-Euk

329r

<3

135

C1-

8080

Euk

328f

-CH

LO02

<3

195

E1-

8080

Euk

328f

-Euk

329r

<3

69S

t3

Alg

eria

nB

asin

37°9

8′N

03°8

3′E

16-S

ep-9

9C

3-5

5E

uk32

8f-C

HLO

02<

316

5E

3-5

5E

uk32

8f-E

uk32

9r<

346

C3-

2525

Euk

328f

-CH

LO02

<3

23E

3-25

25E

uk32

8f-E

uk32

9r<

356

C3-

9595

Euk

328f

-CH

LO02

<3

173

E3-

9595

Euk

328f

-Euk

329r

<3

27S

t5

Str

ait

ofS

icily

36°4

7′N

13°3

2′E

18-S

ep-9

9C

5-25

25E

uk32

8f-C

HLO

02<

315

1E

5-25

25E

uk32

8f-E

uk32

9<

316

8C

5-55

55E

uk32

8f-C

HLO

02<

318

5E

5-55

55E

uk32

8f-E

uk32

9r<

313

1S

tM

IOIo

nian

Bas

in33

°98′

N22

°02′

E20

-Sep

-99

CM

-55

Euk

328f

-CH

LO02

<3

173

EM

-55

Euk

328f

-Euk

329r

<3

62C

M-5

050

Euk

328f

-CH

LO02

<3

171

EM

-50

50E

uk32

8f-E

uk32

9r<

310

2C

M-1

1011

0E

uk32

8f-C

HLO

02<

313

4E

M-1

1011

0E

uk32

8f-E

uk32

9r<

311

5S

t9

Tyrr

heni

anB

asin

41°8

8′N

10°4

3′E

28-S

ep-9

9C

9-5

5E

uk32

8f-C

HLO

02<

310

1E

9-5

5E

uk32

8f-E

uk32

9r<

314

4C

9-65

65E

uk32

8f-C

HLO

02<

322

3E

9-65

65E

uk32

8f-E

uk32

9r<

311

9S

tD

YF

Ligu

rian

Bas

in43

°38′

N07

°82′

E30

-Sep

-99

CD

-15

15E

uk32

8f-C

HLO

02<

317

2E

D-1

515

Euk

328f

-Euk

329r

<3

118

CD

-50

50E

uk32

8f-C

HLO

02<

320

1E

D-5

050

Euk

328f

-Euk

329r

<3

196

Eng

lish

Cha

nnel

,F

ranc

eC

oast

aleu

phot

iczo

neA

cces

sion

num

bers

from

EU

7850

54to

EU

7852

55

Ast

an48

°45′

N04

°00′

W21

-Aug

-01

RA

1S

urfa

ceE

uk52

8f-E

uk32

9r>

1218

3

RA

2S

urfa

ceA

LV01

-E

uk32

9r0.

2–3

96

RA

3S

urfa

ceA

LV01

-E

uk32

9r>

1296

Cat

alan

,M

edite

rran

ean

Sea

,S

pain

Coa

stal

euph

otic

zone

Acc

essi

onnu

mbe

rsfr

omE

U78

5256

toE

U78

5301

Bar

celo

naH

arbo

ur41

°23′

N2°

09′E

28-F

eb-0

1B

AF

RA

CT

pico

Sur

face

Euk

A-E

ukB

0.6–

138

BA

FR

AC

Tna

noS

urfa

ceE

ukA

-Euk

B1–

1029

BA

FR

AC

Tm

icro

Sur

face

Euk

A-E

ukB

10–5

027

Cat

alan

,M

edite

rran

ean

Sea

,S

pain

Coa

stal

euph

otic

zone

Acc

essi

onnu

mbe

rsfr

omE

U78

5302

toE

U78

5340

See

also

Mas

sana

etal

.(2

006)

Bla

nes

Bay

41°4

0′N

02°4

8′E

06-N

ov-0

1B

LEN

Rin

f2S

urfa

ceE

K-1

A-5

16-G

C<

215

BLE

NR

D2T

4S

urfa

ceE

K-1

A-5

16-G

CIn

cuba

tion

afte

rfil

trat

ion

<2

15

BLE

NR

L2T

4S

urfa

ceE

K-1

A-5

16-G

CIn

cuba

tion

afte

rfil

trat

ion

<2

21

Atla

ntic

Oce

anP

RO

SO

PE

Coa

stal

euph

otic

zone

Acc

essi

onnu

mbe

rsfr

omE

U79

3942

toE

U79

3987

See

also

Vip

rey

etal

.(2

008)

St

UP

WM

oroc

coup

wel

ling

31°0

2 ′N

10°0

3′W

09-S

ep-9

9C

U-3

030

Euk

328f

-CH

LO02

<3

53

EU

-30

30E

uk32

8f-E

uk32

9r<

312

6

Atla

ntic

Mer

idio

nalT

rans

ect

(AM

T15

)O

cean

iceu

phot

iczo

neA

cces

sion

num

bers

from

EU

7805

89to

EU

7806

36S

eeal

soZ

wirg

lmai

eret

al.

(200

7)

Nor

ther

nco

asta

lS

tatio

n1

48°7

4′N

7°08

′W19

-Sep

t-04

AM

T15

-110

Euk

328f

-Euk

329r

<3

217

Upw

ellin

gS

tatio

n15

17°8

3′N

20°8

9′W

04-O

ct-0

4A

MT

15-1

510

Euk

328f

-Euk

329r

<3

207

Sou

ther

ngy

reS

tatio

n27

23°5

6′S

17°4

9′W

18-O

ct-0

4A

MT

15-2

730

Euk

328f

-Euk

329r

<3

119

Sou

ther

nte

mpe

rate

Sta

tion

3337

°83′

S1°

23′E

24-O

ct-0

4A

MT

15-3

35

Euk

328f

-Euk

329r

<3

234

Diversity of parasitic Syndiniales 3351


Tab

le1.

cont

.

Env

ironm

ent

and

crui

seS

tatio

nan

dS

iteC

oord

inat

esD

ate

Cod

elib

rary

Dep

th(m

)P

rimer

Sam

ple

deta

ils(m

m)

Tota

lnum

ber

ofcl

ones

with

inse

rtsc

reen

ed

Flo

rida

Str

aits

,Atla

ntic

Oce

anC

oast

aleu

phot

iczo

neA

cces

sion

num

bers

from

EU

8185

67to

EU

8186

91an

dE

U83

6584

toE

U83

6597

Sta

tion

125

°30′

N80

°04′

W31

-Mar

-05

FS

01B

5E

uk32

8f-E

uk32

9r<

290

25°3

0′N

80°0

4′W

31-M

ar-0

5F

S01

C70

Euk

328f

-Euk

329r

<2

85

25°3

0′N

80°0

3′W

01-A

ug-0

5F

S01

A5

Euk

328f

-Euk

329r

<2

85

25°3

0′N

80°0

3′W

01-A

ug-0

5F

S01

D65

Euk

328f

-Euk

329r

<2

85

Flo

rida

Str

aits

,Atla

ntic

Oce

anO

cean

iceu

phot

iczo

neA

cces

sion

num

bers

from

EU

8180

78to

EU

8185

66an

dE

U83

6598

toE

U83

6612

Sta

tion

425

°30′

N79

°57′

W31

-Mar

-05

FS

04E

5E

uk32

8f-E

uk32

9r<

281

25°3

0′N

79°5

7′W

31-M

ar-0

5F

S04

F85

Euk

328f

-Euk

329r

<2

88

25°3

0′N

79°5

7′W

01-A

ug-0

5F

S04

G5

Euk

328f

-Euk

329r

<2

90

25°3

0′N

79°5

7′W

01-A

ug-0

5F

S04

H89

Euk

328f

-Euk

329r

<2

169

Sta

tion

1425

°29′

N79

°20′

W30

-Mar

-05

FS

14I

70E

uk32

8f-E

uk32

9r<

274

25°2

9′N

79°2

0′W

30-M

ar-0

5F

S14

J5

Euk

328f

-Euk

329r

<2

90

25°2

9′N

79°2

0′W

31-J

ul-0

5F

S14

K5

Euk

328f

-Euk

329r

<2

69

25°2

9′N

79°2

0′W

31-J

ul-0

5F

S14

L80

Euk

328f

-Euk

329r

<2

83

25°2

9′N

79°2

0′W

Dec

-08

FS

14M

58E

uk32

8f-E

uk32

9r<

283

25°2

9′N

79°2

0′W

Dec

-08

FS

14N

58E

uk32

8f-E

uk32

9r�

281

Sar

gass

oS

eaA

tlant

icO

cean

Oce

anic

euph

otic

zone

Acc

essi

onnu

mbe

rsfr

omE

U81

7966

toE

U81

8077

and

EU

8366

13to

EU

8366

15

Ber

mud

aA

tlant

icTi

me-

Ser

ies

Sta

tion

31°3

9′N

64°3

7′W

29-M

ay-0

5O

C41

3BA

TS

_O75

Euk

328f

-Euk

329r

<2

90

01-J

un-0

5O

C41

3BA

TS

_P15

Euk

328f

-Euk

329r

<2

87

Sar

gass

oS

ea,A

tlant

icO

cean

Oce

anic

euph

otic

zone

Acc

essi

onnu

mbe

rsfr

omE

U81

7882

toE

U81

7965

+E

U83

6616

toE

U83

6617

35°0

9′N

66°3

3′W

05-J

un-0

5O

C41

3NS

S_Q

15E

uk32

8f-E

uk32

9r<

284

08-J

un-0

5O

C41

3NS

S_R

70E

uk32

8f-E

uk32

9r<

283

Tota

lnum

ber

ofcl

ones

6874

For

furt

her

info

rmat

ion

onth

epr

imer

sus

ed,

see

also

Tabl

eS

2.A

cces

sion

num

bers

are

prov

ided

for

dino

flage

llate

sequ

ence

son

ly.



(150 clone libraries, mostly from freshwater, sedimentsand soils). Taken together, this resulted in 4844 dinoflagel-late sequences from these environmental data sets, with1164 and 2435 belonging to MALV groups I and II respec-tively (Table 2). An additional 727 sequences werederived from dinoflagellate cultures including a few fromthe amplification of single cells (see Table 2), most ofthese belonging to marine photosynthetic dinoflagellates(a bias already pointed out by Murray et al., 2005). Themean length of the dinoflagellate sequences in the data-base was 950 nucleotides (range 108–1841 bp).

Phylogenetic analyses

Dinoflagellate sequences longer than 1600 bp (1018sequences in total, 291 retained for the final tree, see thecomplete list of sequences in the Table S1) were used toperform phylogenetic analyses. Sequences belonging tothe major Alveolata lineages were also included (Fig. 1).In order to avoid long-branch attraction artefacts, highlydivergent alveolate groups were removed after prelimi-nary phylogenetic analyses by neighbour joining (NJ).These divergent groups included Haemosporida (Apicom-plexa including the human parasite Plasmodium), twociliate groups, Mesodiniidae (Myrionecta and Mesod-inium) and Ellobiopsidae (Silberman et al., 2004). Highlydivergent dinoflagellates, such as members of Noctilu-cales and Oxyrrhis marina, were also excluded. Bayesianphylogeny, using 1137 positions in the 18S rRNA genesequence alignments, delineated four primary lineageswithin the Alveolata (Fig. 1), the ciliates, the Apicomplexa,the Perkinsea and the Dinophyceae. As previouslyobserved (Leander and Keeling, 2003; Groisillier et al.,2006), ciliates fell in the basal region of the tree, followedby Apicomplexa (Fig. 1). Perkinsea are the closest rela-tives of dinoflagellates. As frequently found in 18S rRNAgene phylogenies, many of these backbone nodes did notretain bootstrap support. At the basal part of Dino-phyceae, several distinct taxa were placed in the baye-sian analysis, here termed Syndiniales groups I–V, as amonophyletic lineage (Fig. 1). The general tree topologyobtained with maximum likelihood (ML) was similar (datanot shown). The existence of environmental MALV GroupI and II was previously described (López-García et al.,2001; Moon-van der Staay et al., 2001), but hererenamed (Syndiniales groups I and II) given more defini-tive placement within the Syndiniales. The genetic diver-sity and clade nomenclature of Syndiniales groups I and IIare described in detail in separate analyses using partialsequences (Figs 2 and 3). For the definition of clades, wemodified the general criteria chosen by Groisillier andcolleagues (2006) so that a clade must (i) contain envi-ronmental sequences from at least 2 different clone librar-ies, and (ii) be bootstrap supported, at the defining nodes,Ta

ble

2.E

nviro

nmen

tty

pes

repr

esen

ted

by18

SrR

NA

gene

sequ

ence

sco

nsid

ered

here

in,

and

the

prop

ortio

nfa

lling

with

inth

eD

inofl

agel

lata

.

Orig

inof

the

sequ

ence

s(n

umbe

rof

clon

elib

rarie

sco

nsid

ered

)

Num

ber

of18

SrR

NA

gene

sequ

ence

s

Num

ber

ofse

quen

ces

belo

ngin

gto

dino

flage

llate

s

Num

ber

ofse

quen

ces

per

dino

flage

llate

grou

p

Syn

dini

ales

Gro

upI

Syn

dini

ales

Gro

upII

Syn

dini

ales

Oth

ers

‘Cor

e’di

nofla

gella

tes

Cul

ture

san

dis

olat

esa

2179

572

7(3

.3%

)13

(1.8

%)

24(3

.3%

)9

(1.2

%)

681

(93.

7%)

Env

.C

ontin

enta

l(1

50)

571

135

(0.6

%)

00

35(1

00%

)P

lank

ton

from

the

wat

erco

lum

n(4

2)1

213

35(2

.9%

)0

00

35(1

00%

)B

iofil

m/m

icro

bial

mat

s(1

6)39

20

00

00

Soi

l(3

9)3

361

00

00

0S

edim

ent

(30)

438

00

00

0O

ther

s:ae

roso

l,fe

rmen

tor,

gut

com

mun

ities

...(

23)

307

00

00

0E

nv.

Mar

ine

(347

)16

149

4809

(29.

8%)

1151

(23.

9%)

2411

(50.

1%)

156

(3.2

%)

1091

(22.

7%)

Pla

nkto

nfr

omth

ew

ater

colu

mn

(262

)13

528

4494

(33.

2%)

1073

(23.

9%)

2315

(51.

5%)

154

(3.4

%)

952

(21.

2%)

Sed

imen

t(4

6)1

624

139

(8.6

%)

54(3

8.8%

)18

(12.

9%)

067

(48.

2%)

Oth

ers:

biofi

lm,

incu

batio

n,gu

tco

mm

uniti

es..

.(39

)99

717

6(1

7.7%

)24

(13.

6%)

78(4

4.3%

)2

(1.1

%)

72(4

0.9%

)

Tota

l43

655

5571

(12.

8%)

1164

(20.

9%)

2435

(43.

7%)

165

(3.0

%)

1807

(31.

5%)

a.In

clud

ing

anal

ysis

ofsi

ngle

cells

.E

nv.

mea

nsen

viro

nmen

tals

eque

nces

.The

num

ber

ofcl

one

libra

ries

scre

ened

for

each

envi

ronm

ent

isgi

ven

inbr

acke

tsin

the

first

colu

mn.

Inco

lum

ns4–

7,br

acke

tsin

dica

te,

asa

perc

enta

ge,

the

num

ber

ofse

quen

ces

obta

ined

for

apa

rtic

ular

dino

flage

llate

grou

pco

mpa

red

with

the

corr

espo

ndin

gen

viro

nmen

t(c

olum

n3)

.‘C

ore’

dino

flage

llate

sm

eans

all

dino

flage

llate

sex

cept

Syn

dini

ales

.



by values greater than 60% in NJ and maximum parsi-mony (MP) analysis. Some exceptions to these rules weremade as detailed below. The mean sequence identitywithin a clade was 87% for Syndiniales Group I (rangingfrom 76.6% for clade 5 to 91.9% for clade 7) and 93.5%for Syndiniales Group II (ranging from 80.8% for clade 8 to99.4% for clades 35 and 43, see also Fig. S1). Syndini-ales Group I contained eight different clades (Fig. 2).Clades 1–5 were described previously by Groisillier andcolleagues (2006), while three new clades emerged fromthis study. All of these eight clades are supported bybootstrap values > 60%, except for Clade 3, which is onlysupported by MP, bootstrap analyses (74%). Neverthe-less, the tree topology is identical with the two differentmethods (NJ and MP) and minimal sequence identitieswithin this clade are inside the range of other clades

belonging to this group (see Fig. S1). Ichthyodinium chab-erladi, a parasitoid of fish eggs, belongs to Group I Clade3, while Duboscquella spp., a parasitoid of tintinnides,belongs to Group I Clade 4 (Harada et al., 2007). Syndini-ales sequences retrieved by single-cell PCR on radiolar-ian isolates (Dolven et al., 2007) belong to Clade 1(DQ916408, though not in the tree because this sequencecontained several nucleotide ambiguities) and Clade 2(DQ916404–DQ916407 and DQ916410). Clades 5–8 areonly composed of environmental sequences. Somesequences within clades 1–4 (highlighted in grey in Fig. 2)were retrieved exclusively from suboxic and anoxicecosystems. Together, clades 1 and 5 were the mostcommonly retrieved from environmental clone libraries,representing � 75% of sequences belonging to Syndini-ales Group I.

DQ504327 LC22-5EP-44

DQ925237 CsH1AF421184 Hematodinium sp.EF065718 Hematodinium pereziEF065717 Hematodinium pereziEF172791 SSRPB76

DQ504356 LC22-5EP-37EU793192 E1-80m.27DQ146406 Syndinium sp.DQ146404 Syndinium turboDQ146403 Syndinium turboDQ146405 Syndinium turbo

AF286023 Hematodinium sp.

IV

EU562105 IND72.28EU818223 FS04H087_89mEU793790 EM-110m.171EU793574 ED-15m.111

EU562107 IND72.30EU780615 AMT15_15B_12EU818001 OC413BATS_O020_75m

EU793839 EM-50m.113EU818407 FS14JA31_5m

V

EU793465 E9-5m.27EU793466 E9-5m.29

EU561787 IND31.121DQ344732 TWS091

EU562079 IND72.02EU817912 OC413NSS_Q043_15m

EU818259 FS04F028_85mEU817911 OC413NSS_Q031_15m

EU793593 ED-15m.135EU793324 E5-25m.204DQ918792 ENVP36162.00253

AY664993 SCM15 C23EU818113 FS04G196_5mEU818541 FS14N090_58m

EU818542 FS14N072_58mEU561731 IND31.60EU818431 FS14K050_5mEU818080 FS04G102_5m

EU780604 AMT15_1B_36EF539059 MB01.33

EU818673 FS01D005_65mAY295467 RA000609.43EU818141 FS04GA80_5mAY426937 BL010625.44EU818430 FS14K031_5m

EU818672 FS01D055_65mEU793987 EU-30m.99

EU818014 OC413BATS_O095_75mEU793515 E9-65m.113

EU818655 FS01D056_65mDQ918274 ENVP21819.00021

EU818152 FS04H034_89mAJ402349 OLI11005

DQ918653 ENVP223.00266EF526769 NIF 4C5

DQ310226 FV23 1E1DQ918940 ENVP366.00147

DQ918434 ENVP21819.00364EU818349 FS14I039_70mEU793615 ED-15m.57

EU793164 E1-30m.67EU793978 EU-30m.74EU793475 E9-5m.53EU793818 EM-110m.215

EF539065 TH07.15DQ647514 CD8.10EU562048 IND70.56EU780607 AMT15_1B_40

EU793959 EU-30m.3DQ918980 ENVP366.00230

EF527026 SIF 3A10EF527085 SIF 4E8EF527091 SIF 4G12

2%

III

Otherdinoflagellates

II

Syndinium turboHematodinium spp. III

IV

PerkinseaColpodellidae

CoccidiaPiroplasmida

Cryptosporidium spp.

Ciliates

Apicomplexa

IV

10%

AY665063 SCM38 C14 AF133909 Parvilucifera

Und. Apicomplexa 1

GregariniaColpodellidae Und. Apicomplexa 2

Outgroups

100/100

100/100

80/-

98/95

100/99

64/-

100/100

100/100

100/100100/100

99/82

100/99

Syndiniales

Dinophyceae

Fig. 1. Phylogeny of dinoflagellates using near-complete 18S rRNA gene sequences. Left: Bayesian phylogeny of alveolates based onanalysis of 291 near full-length 18S rRNA gene sequences. Five sequences of Bolidophyceae (stramenopiles) were used as an outgroup.Gblock retained 1137 positions for the phylogenetic analyses. Bootstrap values, given at the principal nodes of the tree, correspond toneighbour-joining and maximum parsimony analyses respectively (1000 replicates, values > 60% shown). For neighbour-joining bootstrapping,a GTR + G + I model was selected with the following parameters: Lset Base = (0.2757 0. 1787 0.2494), Nst = 6, Rmat = (1.0746 2.96001.2514 1.0820 4.7079), Rates = gamma, Shape = 0.7091, Pinvar = 0.2330. The scale bar corresponds to 10% sequence divergence. Inset (atthe right): Details of groups III to VI, based upon analysis of partial (500 bp) sequences (59 sequences including outgroups). The scale barcorresponds to 2% sequence divergence. The two sequences in grey belonging to Group IV are from hydrothermal vents.



DQ

1865

36 B

L010

320.

28EU

7939

79EU

-30m

.76

DQ

5043

29 L

C23

4EP

1D

Q50

4313

LC2

2 4E

P 17

AF2

9007

3 D

H14

7 EK

D18

AY0

4668

1 A

1 E0

14A

Y046

671

A1

E004

EU81

8534

FS14

N04

1_58

mA

Y664

995

SCM

38 C

41EF

2190

11 1

8BR5

DQ

5043

30 L

C23-

4EP

9A

B276

368

Icht

hyod

inium

chab

elar

diA

B264

776

Icht

hyod

inium

chab

elar

diD

Q34

0768

Ich

thyo

dinium

chab

elar

diEF

1728

30 S

SRP

B64

AY0

4686

2 C3

E03

4A

Y256

307

CAR

D 8

0A

F530

539

AT4

47

AY2

5630

5 CA

R D

76

AB2

7510

9 CP

SGM

-2A

J402

353

OLI

011

75m

33(

5)EU

7934

03 E

5-55

m.2

72EU

8181

48FS

04GA

93_5

mA

Y665

100

SCM

27 C

13A

Y665

089

SCM

15 C

33D

Q50

4334

LC2

3 5E

P 9

AY6

6510

2 SC

M15

C4

AJ4

0235

2 O

LI01

1 75

m 2

9EU

7938

21EM

-110

m.2

21A

Y665

092

SCM

37 C

51EU

8185

58FS

14N

029_

58m

EU81

8566

FS14

N07

4_58

mEU

5619

18 I

ND

58.5

8A

Y256

213

CAR

H 4

8EU

8182

58FS

04F0

78_8

5mEU

7938

74EM

-50m

.63

AY4

2690

9 BL

0103

20.2

9EU

7932

18E3

-25m

.129

EU81

8466

FS1

4L00

3_80

m

EU79

3788

EM-1

10m

.169

EU81

8079

FS04

G101

_5m

AY2

5624

3 CA

R E

3A

Y882

464

Cari

aco

T60

A6

AY2

5630

4 CA

R D

75

AY1

2905

6 U

EPA

C Q

p5A

Y129

058

UEP

AC

Dp5

DQ

1038

12 M

aria

ger

Fjor

d 4

18F0

5A

B252

761

NA

MA

KO-2

1A

Y046

800

C2 E

009

AB2

7502

8 D

SGM

-28

EF17

2822

SS

RPB8

4EU

8185

63 F

S14N

018_

58m

DQ

1199

19 N

OR5

0.33

EU56

2061

IN

D70

.70

EU79

3735

ED-5

0m.5

4EU

8182

56FS

04F0

66_8

5mD

Q18

6529

RA

0012

19.4

0EU

5620

41IN

D70

.49

AJ4

0235

4 O

LI01

1 75

m 1

1EU

7935

50E9

-65m

.65

AY4

2683

1 BL

0009

21.0

4A

Y256

267

CAR

E 13

1A

B275

027

DSG

M-2

7A

Y882

465

Cari

aco

p14B

3A

Y665

057

SCM

27 C

44

AY8

8244

9 Ca

riac

oT

45F1

2EU

7931

62 E

1-30

m.6

4EU

7934

47 E

9-5m

.135

EU81

8298

FS04

E068

_5m

AB2

9504

0 Dub

oscq

uella

sp.

Ishika

ri/2

003

AB2

9504

1 Dub

oscq

uella

sp.

Ham

ana/

2003

AY8

8247

5 Ca

riac

op1

5F05

EU81

7922

OC4

13N

SS_R

067_

70m

EF17

2986

SS

RPD

80-

96 S

SRP

D84

EU81

8085

FS04

G116

_5m

EU78

0633

AM

T15_

33B_

25EU

8180

12O

C413

BATS

_O09

3_75

mEU

5618

78 I

ND

33.8

2EU

7934

04 E

5-55

m.2

78D

Q11

9907

NW

614.

29D

Q11

9893

NO

R26.

25EU

7937

65 E

M-1

10m

.100

EU79

3223

E3-

25m

.89

EU81

8682

FS

01D

039_

65m

EU81

7993

OC4

13BA

TS_O

009_

75m

EU78

0622

AM

T15_

33B_

14EF

5390

20 T

H10

.8A

Y665

056

SCM

37 C

30EU

5620

05 I

ND

70.0

5EU

8182

64 F

S04

F024

_85m

EU79

3915

EM

-5m

.166

EU81

7990

OC4

13BA

TS_O

054_

75m

EU79

3939

EM

-5m

.7EU

8179

68 O

C413

BATS

_O07

4_75

mA

Y129

029

UEP

AC

Cp1

EU81

8112

FS

04G1

94_5

mEU

7936

47ED

-50m

.123

EU79

3757

ED

-50m

.87

AY6

6502

8 SC

M27

C22

DQ

1451

14O

LI01

1 75

m 8

6EU

8186

53 F

S01

C081

_70m

EU79

3245

E3-

5m.3

6EU

8178

97 O

C413

NSS

_Q01

5_15

mA

Y426

850

BL00

0921

.32

EU56

2090

IN

D72

.13

EF17

2944

SS

RPD

58-

79 S

SRP

D60

AF2

9006

6 D

H14

5 EK

D10

EU79

3621

ED

-15m

.63

EU81

8550

FS1

4N00

7_58

mEU

7806

03 A

MT1

5_1B

_35

EU79

3808

EM

-110

m.2

01EF

1728

15 S

SRPB

SSR

PB38

EU81

8393

FS1

4JA

63_5

mA

Y665

031

SCM

28 C

139

EU56

1865

IN

D33

.68

EU79

3552

E9-

65m

.68

EF21

9009

18B

R9EU

8186

32 F

S01

C017

_70m

EU79

3944

EU

-30m

.108

EU81

8351

FS14

I095

_70m

EU56

1806

IN

D31

.141

AJ4

0232

8 O

LI01

1 75

m 3

8EU

7938

49 E

M-5

0m.2

4A

Y665

036

SCM

38 C

5EU

8186

34 F

S01

C016

_70m

AY6

6502

2 SC

M37

C49

EU56

1880

IN

D58

.02

EU81

8556

FS1

4N04

4_58

mA

J402

327

OLI

011

75m

1(1

)EU

7935

85 E

D-1

5m.1

25EU

8184

34 F

S14K

044_

5mEU

5620

65 I

ND

70.7

4A

Y665

030

SCM

28 C

103

DQ

5043

16 L

C22

5EP

6D

Q11

9903

NW

414

16EU

8179

95 O

C413

BATS

_O08

5_75

mEU

8179

57 O

C413

NSS

_R05

0_70

mD

Q11

9909

NW

614

53D

Q91

6405

Rad

iolarian

para

site

s?D

Q11

9899

NO

R50.

42EU

8184

74 F

S14L

061_

80m

AY2

5624

6 CA

R E

12 2

EF17

2831

SS

RPB4

5A

B275

022

DSG

M-2

2EU

8184

87 F

S14M

064_

58m

AY0

4662

4 C1

E02

3A

Y046

652

CS E

027

AF5

3053

8 A

T8

27A

B275

023

DSG

M-2

3D

Q91

6406

Rad

iolarian

para

site

s?A

Y256

276

CAR

E 18

8A

F290

078

DH

148

EKD

22A

Y046

841

C3 E

011

EU79

3825

EM

-110

m.2

29

AY4

2687

3 BL

0012

21.2

4EU

8484

95 E

D-1

5m.1

07D

Q38

6754

AP-

pico

clon

e18

EU81

8602

FS01

B067

_5m

EU81

8671

FS0

1D04

2_65

mA

Y046

650

CS E

023

AB2

7502

4 D

SG

M-2

4A

Y665

019

SCM

16 C

10D

Q11

9900

NO

R50.

53EU

5616

96 I

ND

31.2

3D

Q31

0231

FV3

6 2E

08A

Y882

462

Cari

aco

T41

A6

EF17

2971

G11

N10

EU81

8567

FS

01A

A06

_5m

EF17

2983

SSR

PD 8

0-96

SSR

PD80

EU79

3571

ED

-15m

.100

DQ

1199

04 N

W41

4.35

EU81

7910

OC4

13N

SS_Q

061_

15m

AY4

2689

8 BL

0103

20.1

2A

Y665

044

SCM

38 C

44A

Y046

711

A1

E045

AB1

9141

8 TA

GIRI

10

EU81

8068

OC4

13BA

TS_P

043_

15m

EU81

8560

FS

14N

038_

58m

EU56

1736

IN

D31

.65

EU78

0601

AM

T15_

1B_3

3EU

7938

29 E

M-1

10m

.238

AY4

2692

4 BL

0106

25.1

5A

Y129

048

UEP

AC

36p4

DQ

3867

52 A

P-pi

cocl

one

16D

Q11

9894

NO

R46.

05EU

8178

94 O

C413

NSS

_Q04

4_15

mEU

7933

14 E

5-25

m.1

89A

Y426

887

BL00

1221

.41

EU56

1934

IN

D58

.80

EU79

3385

E5-

55m

.161

AY4

2693

6 BL

0106

25.4

2EU

7931

95 E

1-80

m.3

4D

Q31

0327

FV2

3 1C

7G8

EU79

3687

ED

-50m

.189

DQ

1199

01 N

OR5

0.54

EU56

1927

IN

D58

.68

EU81

8603

FS

01B0

66_5

mEU

8182

32 F

S04

H13

5_89

mEF

1729

54 S

SRP

D 5

8-79

SS

RPD

70EU

7934

30 E

9-5m

.111

AY4

2690

3 BL

0103

20.2

0EU

8186

39 F

S01

C095

_70m

EU56

2073

IN

D70

.83

AB2

5276

2 N

AM

AKO

-22

EF17

3015

Q2G

10N

5EU

7937

30 E

D-5

0m.4

8EU

5619

91 I

ND

60.7

5A

Y665

054

SCM

28 C

151

DQ

1198

95 N

OR5

0.13

EU56

1962

IN

D60

.40

EU79

3401

E5-

55m

.269

EU81

8525

FS

14M

022_

58m

DQ

1199

08 N

W61

4 50

EU78

0617

AM

T15_

15B_

17A

Y046

827

C2 E

042

AB2

7502

5 D

SGM

-25

AY0

4661

2 C1

E00

8EU

5616

77 I

ND

31.1

AY0

4683

3 C3

E00

3A

Y426

900

BL01

0320

.15

EU81

7882

OC4

13N

SS_Q

083_

15m

AB2

7502

6 D

SG

M-2

6D

Q38

6746

AP-

pico

clon

e10

EU79

3505

E9-

5m.9

8A

B191

417

TAGI

RI 9

EF17

2996

SSR

PD 8

0-96

SS

RPD

95A

Y256

328

CAR

D 2

05EU

5621

35 I

ND

72.6

0EF

1730

07 Q

2A12

N5

EU78

0616

AM

T15_

15B_

16EF

1729

78 Q

2D12

N10

EU81

8166

FS

04H

154_

89m

EF17

2813

SSR

PB S

SRPB

66A

F530

537

AT

4 42

AY8

8246

7 Ca

riac

op1

5H09

10%

3 6 8

4

EU79

3351

E5-2

5m.2

42EU

7933

28 E

5-25

m.2

09EU

7932

89E5

-25m

.152

EU79

3326

E5-2

5m.2

07EU

5620

16 I

ND

70.1

8EU

7934

56E9

-5m

.16

EU56

2010

IN

D70

.12

AY6

6499

9 SC

M37

C10

EU56

2108

IN

D72

.31

7

5

2

1

-/74 100/

100

100/

100

100/

96

99/9

4

100/

100

99/9

5 100

/100

97/9

7

100/

99

77/6

4

Fig

.2.

Phy

loge

nyof

Syn

dini

ales

Gro

upI.

Nei

ghbo

ur-jo

inin

gph

ylog

eny

ofA

lveo

late

Gro

upI,

base

dup

onth

ean

alys

isof

275

part

ials

eque

nces

,73

1bp

inle

ngth

(incl

udin

gou

tgro

ups,

not

show

n).A

GT

R+

Gm

odel

was

sele

cted

usin

gth

efo

llow

ing

para

met

ers:

Lset

Bas

e=

(0.2

627

0.18

100.

2622

),N

st=

6,R

mat

=(1

.000

02.

8775

1.00

004.

6908

),R

ates

=ga

mm

a,S

hape

=0.

5006

,P

inva

r=

(0).

Boo

tstr

apva

lues

,gi

ven

atth

epr

inci

paln

odes

ofth

edi

ffere

ntcl

ades

,co

rres

pond

tone

ighb

our-

join

ing

and

max

imum

pars

imon

yan

alys

esre

spec

tivel

y(1

000

repl

icat

es,

valu

es>

60%

show

n).

The

scal

eba

rco

rres

pond

sto

10%

sequ

ence

dive

rgen

ce.

The

tree

was

cut

inor

der

tobe

tter

sepa

rate

the

maj

orcl

ades

inth

efig

ure.

Seq

uenc

esin

grey

are

from

hydr

othe

rmal

and

subo

xic

ecos

yste

ms.



EU79

3692

ED

-50m

.199

EU79

3975

EU-3

0m.6

7

100/

100

62/7

3

98/8

3

92/8

6

72/8

6

79/-

98/9

2

73/-

85/7

4

83/7

4

EU81

8034

OC4

13BA

TS_P

045_

15m

EU81

8600

FS

01B0

46_5

mEF

1729

68 F

11N

10A

F239

260

Amoe

boph

rya

ex D

inop

hysi

ssp

.EU

8180

15 O

C413

BATS

_O04

6_75

mEU

8186

25 F

S01

B031

_5m

EU79

3356

E5-

25m

.249

EU79

3494

E9-

5m.7

7A

F069

516

Amoe

boph

rya

ex A

kash

iwo

sang

uine

aEU

8180

16 O

C413

BATS

_O07

2_75

mEU

7937

98 E

M-1

10m

.189

EU81

8132

FS0

4GA

43_5

mEU

8184

61 F

S14L

069_

80m

AY1

2903

8 U

EPA

C Ep

3A

J402

326

OLI

011

75m

1-1

(5)

EU81

8573

FS

01A

A57

_5m

EU81

8537

FS1

4N01

0_58

mEU

8179

75 O

C413

BATS

_O00

6_75

mEU

7939

06 E

M-5

m.15

1EU

8186

61 F

S01D

088_

65m

EU79

3894

EM

-50m

.93

AF4

7255

5 Am

oebo

phry

aex

Scr

ipps

iella

sp.

DQ

3867

53 A

P-pi

cocl

one

17EU

8186

65 F

S01

D02

3_65

mA

Y129

040

UEP

AC

Fp3

EU81

8424

FS1

4K01

9_5m

EU81

8661

FS

01D

088_

65m

EU81

8645

FS

01C0

72_7

0mA

Y775

285

Amoe

boph

rya

ex G

onya

ulax

poly

gram

ma

DQ

3867

57 A

P-pi

cocl

one

21EU

8186

79 F

S01

D04

1_65

mEU

8180

87 F

S04

G119

_5m

AF4

7255

4 Am

oebo

phry

aex

Gym

nodi

nium

inst

riat

umA

Y775

284

Amoe

boph

rya

ex A

lexa

ndri

umaf

fine

EU81

8375

FS1

4JA

68_5

mEU

8183

81 F

S14

JA02

_5m

EU81

8570

FS

01A

A30

_5m

EU79

3954

EU

-30m

.19EU

8179

18 O

C413

NSS

_Q06

0_15

mA

Y129

046

UEP

AC

Dp4

EU81

8664

FS

01D

073_

65m

AY2

0889

3 Am

oebo

phry

aex

Pro

roce

ntru

mm

ican

sA

Y208

892

Amoe

boph

rya

ex C

erat

ium

trip

osA

Y129

054

UEP

AC

APp

5EU

8181

42 F

S04G

A81

_5m

EU81

8052

OC4

13BA

TS_P

007_

15m

EU81

8473

FS1

4L08

8_80

mEU

7934

08 E

5-55

m.2

85EU

8184

86 F

S14M

003_

58m

EU79

3322

E5-

25m

.202

EU81

8533

FS1

4N05

2_58

mA

F290

077

DH

148-

EKD

27A

Y885

029

BB01

80

DQ

3867

56 A

P-pi

cocl

one

20EU

8179

19 O

C413

NSS

_Q09

6_15

mEU

8186

36 F

S01

C003

_70m

EU81

7954

OC4

13N

SS_R

084_

70m

EU81

8110

FS0

4G18

5_5m

AY8

8502

7 BB

01 8

3D

Q18

6528

RA

0012

19.1

6D

Q11

9926

NW

414.

13EU

7939

58 E

U-3

0m.2

9EU

8186

77 F

S01

D01

2_65

mEU

8180

66 O

C413

BATS

_P01

1_15

mEF

1730

06 N

5 Q

2A03

EU79

3785

EM

-110

m.1

63EU

8178

86 O

C413

NSS

_Q02

3_15

mEU

8182

79 F

S04

E046

_5m

EU79

3609

ED

-15m

.40

EU56

2025

IN

D70

.27

EU79

3446

E9-

5m.13

3EU

7933

06 E

5-25

m.1

74EU

8186

78 F

S01

D09

5_65

mEU

8178

88 O

C413

NSS

_Q05

7_15

mD

Q18

6531

RA

0104

12.2

9D

Q11

9927

NW

414.

25A

Y208

894

Amoe

boph

rya

ex P

roro

cent

rum

min

imum

AY1

2904

3 U

EPA

C 18

p4D

Q14

5107

OLI

0117

5.31

EF17

3016

Q2G

12N

5D

Q11

9912

MD

65 2

5EU

8180

45 O

C413

BATS

_P09

1_15

mEU

7935

41 E

9-65

m.5

0EU

7806

05 A

MT1

5_1B

_37

EU81

8227

FS

04H

080_

89m

EU81

8075

OC4

13BA

TS_P

087_

15m

EU79

3383

E5-

55m

.147

DQ

1865

26 R

A00

0609

.21

EU81

8140

FS0

4GA

75_5

mEU

5619

14 I

ND

58.5

421

3611

0 Sa

rgas

soVe

nter

213

6110

AF4

7255

3 Am

oebo

phry

aex

Kar

lodi

nium

vene

ficu

mEU

7937

10 E

D-5

0m.2

29EU

8184

58 F

S14L

095_

80m

EU81

8251

FS0

4F07

9_85

mA

Y129

031

UEP

AC

05A

p2EU

8184

56 F

S14L

057_

80m

EU79

3968

EU

-30m

.5EU

7937

06 E

D-5

0m.2

24EU

8182

75 F

S04

E039

_5m

EF17

2965

B03

N10

AJ4

0233

8 O

LI01

1 75

m 2

6(1)

DQ

1199

20 N

OR5

0.35

EU56

2052

IN

D70

.60

AY6

6500

1 S

CM37

C20

EU81

8356

FS1

4JA

94_5

m EU79

3112

E1-

30m

.113

EU79

3120

E1-

30m

.125

EU79

3127

E1-

30m

.133

3 2

33

4

4225

39 5

1

41

EU79

2988

C9-

5m.3

6EU

7930

06 C

D-1

5.23

EU79

2994

C9-

5m.6

8EU

7930

16 C

M-1

10m

.104

EU79

3100

CU

-30m

.12

EU79

3026

CM

-110

m.9

5EU

7929

30 C

3-5m

.111

EU79

3059

CM

-50m

.56

EU79

3061

CM

-50m

.63

EU79

3069

CM

-50m

.8EU

7930

76 C

M-5

m.11

3EU

7930

97 C

M-5

m.7

5EU

7929

32 C

3-5m

.122

EU79

2934

C3-

5m.13

0EU

7929

77 C

5-25

m.7

4EU

7929

48 C

3-5m

.168

EU79

2945

C3-

5m.15

9EU

7929

43C3

-5m

.155

EU79

2942

C3-

5m.15

4EU

7929

40 C

3-5m

.148

99/1

00

97/9

9

10%

24

19

In 3

í10

0/10

0

100/

100

99/1

00

99/9

5

95/8

0

-/-

EU81

8306

FS04

E044

_5m

EU56

1861

IND

33.6

3D

Q11

9915

NO

R46.

30EU

8179

59O

C413

NSS

_R06

1_70

mEU

7936

44ED

-50m

.118

EU79

3292

E5-2

5m.15

7A

Y046

755

A2

E047

AB2

5276

3 N

AM

AKO

-23

DQ

1865

25 R

A00

0412

.159

*EU

8180

11O

C413

BATS

_O06

6_75

mD

Q18

6532

RA

0104

12.5

EU56

2063

IND

70.7

2EU

8183

69FS

14JA

60_5

mEU

8182

52FS

04F0

10_8

5mEU

8186

04 F

S01

B064

_5m

EU79

3344

E5-

25m

.233

EU81

8594

FS01

B012

_5m

*EF

1729

94 S

SRP

D 8

0-96

SS

RPD

93 *

AB2

7501

8 D

SGM

-18

*EU

7935

51E9

-65m

.67

AY1

2903

6 U

EPA

C Cp

3EU

8179

74 O

C413

BATS

_O05

9_75

mA

Y129

037

UEP

AC

Hp3

AB2

5276

4 N

AM

AKO

-24

AY1

2905

2 U

EPA

C Ep

5 *

AY1

2905

0 U

EPA

C 43

p4 *

EU79

3122

E1-3

0m.1

28

EU81

8643

FS

01C0

79_7

0mEU

7939

33 E

M-5

m.1

90EU

7806

06 A

MT1

5_1B

_39

*EU

7937

31ED

-50m

.49

*EU

8186

07FS

01B0

57_5

mEU

8185

77FS

01A

A74

_5m

EF17

2942

SS

RPD

58-

79 S

SRP

D58

EU81

8348

FS14

I029

_70m

EU81

8414

FS14

JA43

_5m

EU81

8529

FS14

M04

6_58

mEU

7934

37E9

-5m

.119

EU79

3282

E5-2

5m.1

45EU

8184

42FS

14K0

78_5

mEF

1729

55 S

SRP

D 5

8-79

SS

RPD

71D

Q18

6530

RA

0012

19.5

7EU

7937

49ED

-50m

.77

EU81

8595

FS01

B036

_5m

DQ

1865

33 R

A01

0412

.70

100/

100

23 1219

3228

3844

13 8

AB2

7501

6 D

SGM

-16

100/

100

88/8

5

EU79

3927

EM-5

m.1

82EU

7936

81ED

-50m

.178

EU79

3489

E9-5

m.7

EU81

8575

FS01

AA

72_5

mEU

7935

81ED

-15m

.120

EU79

3394

E5-5

5m.2

19EU

5617

13IN

D31

.40

EU79

2913

OLI

011_

75m

.81 *

EF21

9010

18B

R10

*EU

7938

19EM

-110

m.2

16EU

8179

65O

C413

NSS

_R05

2_70

mEU

7939

63EU

-30m

.4EU

7938

31EM

-110

m.2

41EU

7937

53ED

-50m

.81

EU79

3618

ED-1

5m.6

0EF

1729

87 S

SRPD

80-

96 S

SRP

D85

EU81

8198

FS04

H06

0_89

mA

Y426

911

BL01

0320

.32

EU79

3375

E5-2

5m.8

EU81

8576

FS01

AA

73_5

mEU

5619

01IN

D58

.34

EU81

8332

FS14

I077

_70m

AY4

2688

6 BL

0012

21.4

0EU

7806

00 A

MT1

5_1B

_32

AJ4

0233

5 O

LI01

1 75

m 2

3(5)

EU81

8202

FS04

H06

7_89

mEU

7939

25EM

-5m

.179

EU81

8269

FS04

F047

_85m

AY6

6498

8 SC

M16

C19

AY1

2904

2 U

EPA

C 41

p3A

Y882

474

Cari

aco

p15D

01EU

7938

41EM

-50m

.12

EU81

8605

FS01

B055

_5m

EU56

1715

IND

31.4

2EU

7805

94 A

MT1

5_1B

_25

EU79

3817

EM-1

10m

.214

EF17

3014

Q2G

02N

5D

Q50

4320

LC2

2-5E

P-11

EU56

1841

IND

33.3

9A

Y664

990

SCM

37 C

21EU

7931

32E1

-30m

.142

EU79

3504

E9-5

m.9

6EF

1729

92 S

SRP

D 8

0-96

SS

RPD

91EU

8184

81FS

14L0

32_8

0mD

Q11

9930

NW

617.

25EU

7939

53EU

-30m

.18A

Y129

057

UEP

AC

AFp

5EU

8186

21 F

S01B

069_

5mEU

8178

89O

C413

NSS

_Q01

7_15

mA

Y256

303

CAR

D 6

9A

Y046

614

C1 E

010

AY0

4659

9 CS

E00

1

10 +

11

9

Clos

e to

10

+ 1

1?

EU81

8213

FS04

H17

9_89

mA

Y937

633

ENI4

0076

002

93A

F290

071

DH

147

EKD

16EU

7805

91 A

MT1

5_1B

_21

EU81

8484

FS14

M00

6_58

mEF

1727

97 S

SRPB

79EU

7935

07 E

9-65

m.1

02EF

1727

98 S

SRP

B41

EU79

3345

E5-

25m

.234

EF17

2925

SS

RPC3

2EF

1728

72 S

SRPC

09EU

7936

96 E

D-5

0m.2

04EF

1729

77 Q

2D03

N10

EU79

3347

E5-

25m

.236

EU56

1778

IND

31.11

1EU

5617

85IN

D31

.119

EF17

2800

SS

RPB1

3EF

1728

88 S

SRPC

56EU

8184

69 F

S14L

076_

80m

EU81

8193

FS0

4H02

3_89

m*

EU81

8206

FS

04H

054_

89m

*A

Y665

038

SCM

37 C

19EU

7938

32 E

M-1

10m

.242

EU79

3799

EM-1

10m

.191

EU81

8155

FS04

H01

0_89

mEU

8185

19 F

S14M

052_

58m

EU81

8520

FS1

4M01

7_58

mEU

7939

86 E

U-3

0m.9

3EU

7939

67 E

U-3

0m.4

6EU

7936

55 E

D-5

0m.13

4EF

1729

53 S

SRP

D 5

8-79

SSR

PD69

EU79

3707

ED

-50m

.225

EU81

8196

FS04

H01

9_89

m*

EU56

1848

IN

D33

.47

EU79

3579

ED

-15m

.118

EF17

2923

SSR

PC86

AF2

9006

9 D

H14

7 EK

D3

EU81

8314

FS1

4I00

6_70

mEU

7937

92 E

M-1

10m

.177

EU81

8239

FS

04F0

68_8

5mEU

8484

94 E

5-55

m.14

9EU

8184

29 F

S14K

010_

5mEU

7931

34 E

1-30

m.1

48EU

8181

54 F

S04

H13

2_89

mEU

8180

18O

C413

BATS

_O03

3_75

mEU

8181

95 F

S04H

059_

89m

EF17

2844

SS

RPB5

8EU

8181

94 F

S04H

040_

89m

EU79

3801

EM

-110

m.19

3EF

1728

37 S

SRP

B62

EU81

7944

OC4

13N

SS_R

029_

70m

AY1

2905

5 U

EPA

C Fp

5EU

8181

89 F

S04H

069_

89m

EU79

3838

EM

-50m

.110

AY4

2685

7 BL

0012

21.3

EU79

3734

ED

-50m

.53

EU81

8175

FS0

4H06

4_89

mEF

1729

75 Q

2B12

N10

EU81

8212

FS0

4H15

8_89

mEU

7939

31 E

M-5

m.18

6EU

8185

00 F

S14M

038_

58m

AY2

9557

4 RA

0012

19.8

EU79

3640

ED

-15m

.94

AF2

9006

8 D

H14

7 EK

D6

EF17

2913

SS

RPC3

9EU

5619

13IN

D58

.53

EU81

7973

OC4

13BA

TS_O

031_

75m

DQ

1199

23 N

OR5

0.56

EF17

3017

Q2H

03N

5D

Q11

9925

NW

414.

06A

Y129

039

UEP

AC

AQ

p3EU

7935

26E9

-65m

.127

EU81

8182

FS0

4H17

6_89

m

100/

100

100/

100

99/1

00

99/9

3

99/8

8

72/8

0

92/6

3

64/-

7

29

4043

203627

35

6

EU78

0613

AM

T15_

15B_

9A

J402

348

OLI

011

75m

9EU

5616

82IN

D31

.7EU

8180

65O

C413

BATS

_P08

3_15

mEU

8183

42FS

14I0

64_7

0mEU

7935

34E9

-65m

.20

EU81

8468

FS14

L087

_80m

AY6

6499

7 S

CM37

C7

EU79

3510

E9-6

5m.1

06EU

8183

53FS

14JA

67_5

m

EU79

3288

E5-2

5m.1

51 *

EU81

7941

OC4

13N

SS_R

039_

70m

EU81

8554

FS14

N02

0_58

mEU

7938

53EM

-50m

.30

EU81

7985

OC4

13BA

TS_O

061_

75m

EU79

3563

E9-6

5m.8

8EU

7937

89EM

-110

m.1

70EU

8185

69FS

01A

A12

_5m

EF17

2958

SS

RPD

58-

79 S

SRP

D74

AY1

2904

9 U

EPA

C 42

p4 *

EU79

3470

E9-5

m.3

7EU

7934

96E9

-5m

.85

EU81

8405

FS14

JA47

_5m

EU81

8071

OC4

13BA

TS_P

052_

15m

EU81

8304

FS04

E065

_5m

DQ

1199

14 N

OR2

6.28

AY8

8503

1 BB

01 6

2EU

8186

14FS

01B0

92_5

mEU

7932

66E5

-25m

.103

EU79

3317

E5-2

5m.1

96EU

8183

46FS

14I0

19_7

0mD

Q11

9929

NW

614.

20EU

7938

63EM

-50m

.44

AJ4

0234

4 O

LI01

1 75

m 5

5EU

7933

98E5

-55m

.248

EU81

8688

FS01

D08

6_65

mEU

8178

93O

C413

NSS

_Q06

2_15

mEU

7806

26 A

MT1

5_33

B_18

EU79

3688

ED-5

0m.19

2EU

8184

38FS

14K0

06_5

mEU

8181

51FS

04H

058_

89m

EU79

3411

E5-5

5m.3

03EU

7935

59E9

-65m

.82

EU79

3555

E9-6

5m.7

4

99/9

9

80/-

87/6

4

78/-

16 17

30 26

EU81

8482

FS14

M08

8_58

mEU

7933

49E5

-25m

.239

EU79

3410

E5-5

5m.3

EU81

7920

OC4

13N

SS_R

066_

70m

EF17

3005

H02

N5

EU79

3311

E5-2

5m.18

3EU

8182

18 F

S04

H04

8_89

mEU

5620

06IN

D70

.06

EU79

3198

E1-8

0m.4

1EU

7931

23E1

-30m

.129

EU79

3219

E3-2

5m.1

9EU

8179

53O

C413

NSS

_R00

5_70

mEU

7938

73EM

-50m

.60

EU83

6604

FS1

4JA

35_5

mEU

8183

10 F

S14I

045_

70m

EU56

1881

IND

58.0

3EF

1729

52 S

SRP

D 5

8-79

SS

RPD

68EU

7938

67EM

-50m

.5EF

1730

09 Q

2C03

N5

AY0

4663

4 C1

E03

7A

F530

532

AT

4 21

AY0

4683

5 C3

E00

5A

Y046

630

C1 E

030

AY0

4686

9 C3

E04

2A

B275

017

DS

GM-1

7A

Y046

603

CS E

006

AY0

4661

0 C1

E00

6A

F290

079

DH

148

EKD

14D

Q14

5113

OLI

011

75m

70

EF17

3003

D05

N5

EU81

8267

FS

04F0

73_8

5mEU

7932

24E3

-25m

.97

EF17

2931

SS

RPC0

2D

Q11

9918

NO

R50.

26A

Y129

045

UEP

AC

Bp4

EU79

3111

E1-3

0m.11

1EU

5620

27IN

D70

.29

EU79

3751

ED-5

0m.7

9EU

7933

42E5

-25m

.231

DQ

1199

16 N

OR5

0.19

EU81

8225

FS

04H

001_

89m

EU56

1966

IND

60.4

5EF

1729

45 S

SRPD

58-

79 S

SRP

D61

EU81

8532

FS14

N01

4_58

mEU

7939

09EM

-5m

.154

EU81

8044

OC4

13BA

TS_P

051_

15m

AF2

9007

4 D

H14

7 EK

D19

EU81

8043

OC4

13BA

TS_P

029_

15m

EU81

8273

FS04

E053

_5m

DQ

3867

51 A

P-pi

cocl

one

15EU

7938

16EM

-110

m.2

13EU

5618

59IN

D33

.60

EU79

3877

EM-5

0m.7

EU81

7890

OC4

13N

SS_Q

072_

15m

EU81

8526

FS14

M03

1_58

mD

Q18

6534

RA

0106

13.1

26EU

7938

15EM

-110

m.2

11EU

8184

13FS

14JA

82_5

mEU

7937

84EM

-110

m.1

56D

Q14

5103

OLI

011

75m

17(

5) *

EU56

2109

IND

72.3

2EU

8183

41FS

14I0

28_7

0mEU

8179

50O

C413

NSS

_R02

3_70

mEU

8185

13FS

14M

004_

58m

100/

100

100/

100

100/

100

100/

100

100/

100

100/

98 77/-

93/7

2

87/-

0.05

22

15 31 2

1

14

18 37

34

Cla

de

«A

mo

ebo

ph

rya

»5%

63/8

0

100/

99

81/-

55/-

98/8

5

100/

87

100/

100

65/1

00

100/

100

96/9

3

Fig

.3.

Phy

loge

nyof

Syn

dini

ales

Gro

upII.

Nei

ghbo

ur-jo

inin

gph

ylog

eny

ofA

lveo

late

Gro

upII,

base

dup

onan

alys

isof

423

part

ials

eque

nces

,73

8bp

inle

ngth

and

cent

red

atth

e5′

end

(incl

udin

gou

tgro

ups,

not

show

n).A

GT

R+

Gm

odel

was

sele

cted

usin

gth

efo

llow

ing

para

met

ers:

Lset

Bas

e=

(0.2

736

0.17

000.

2545

),N

st=

6,R

mat

=(1

.000

03.

3780

1.28

041.

2804

4.96

83),

Rat

es=

gam

ma,

Sha

pe=

0.61

08,

Pin

var

=0.

1155

).B

oots

trap

valu

es,

give

nat

the

prin

cipa

lnod

esof

the

diffe

rent

clad

es,

corr

espo

ndto

neig

hbou

r-jo

inin

gan

dm

axim

umpa

rsim

ony

anal

yses

resp

ectiv

ely

(100

0re

plic

ates

,va

lues

>60

%sh

own)

.T

heas

teris

k‘*

’ind

icat

essi

ngle

tons

(seq

uenc

esth

atar

eno

tin

clud

edin

any

clad

es).

The

scal

eba

rco

rres

pond

sto

5%se

quen

cedi

verg

ence

.T

hetr

eew

ascu

tin

orde

rto

bette

rse

para

teth

em

ajor

clad

esin

the

figur

e.In

set:

asm

allp

ortio

nof

the

neig

hbou

r-jo

inin

gtr

eeob

tain

edus

ing

the

3′en

dof

the

18S

rRN

Age

neof

Alv

eola

teG

roup

II,ba

sed

upon

anal

ysis

of36

5pa

rtia

lseq

uenc

es,

617

bpin

leng

th(in

clud

ing

outg

roup

s).

The

scal

eba

rco

rres

pond

sto

10%

sequ

ence

dive

rgen

ce.

Boo

tstr

apva

lues

corr

espo

ndto

neig

hbou

r-jo

inin

gan

alys

es(1

000

repl

icat

es).

Seq

uenc

esin

grey

are

from

hydr

othe

rmal

and

subo

xic

ecos

yste

ms.



By comparison, Syndiniales Group II is genetically morediverse than Group I. In addition to clades 1–16 (seeGroisillier et al., 2006), 28 new clades emerged from thepresent study (clades 17–44, Fig. 3). Some of theseclades are not supported by bootstrap analyses obtainedwith one of the two phylogenetic methods tested (clades2, 6, 10+11, 14, 16, 23, 25 and 26), but in such cases thetree topologies are identical between the two methods.Clade 10 and Clade 11 described by Groisillier and col-leagues (2006) are now merged into a single clade(herein named Clade 10+11), which includes cloneBL10320.32 (a singleton in the work of Groisillier et al.,2006). However, Clade 10+11 is not supported by boot-strap analyses. Numerous environmental sequences dis-playing long branches (labelled ‘close to 10+11?’ in Fig. 3)also appear to be closely related to Clade 10+11.

Only a single genus within Syndiniales Group II hasbeen formally described, the Amoebophrya. AllAmoebophrya sequences obtained from cultures andsingle-cell analyses formed a monophyletic group as rec-ognized by Groisillier and colleagues (2006). This mono-phyletic group now also includes clades 1–5 as well asclades 25, 33, 39, 41 and 42 (Fig. 3). Recently, Kim andcolleagues (2008) recognized nine different subgroupswithin Amoebophrya. Subgroup 1 (from the analysis ofKim and colleagues) corresponds primarily with our Clade1 (except sequence AF290077 which belongs to the novelClade 25) while subgroups 3, 4, 5 and 6 correspond toclades 4, 3, 5 and 2 respectively. The recognition of sub-group 2 (identified in Kim et al., 2008) is probably skewedby inclusion of a sequence we identified to be a chimera(DQ186527). Thus, sequence AY260468, obtained fromthe direct amplification of Ceratium tripos infected withAmoebophrya, likely remains a singleton. SequenceAY295690 (subgroup 8) is also a probable chimera,whereas sequences included within subgroups 7 and 9belong to Clade 33 in the present study. SequenceDQ916402, obtained from the direct amplification of a cellof spumellarida Hexacontium gigantheum (Radiolaria), isclosely related to Clade 6. This sequence was removedfrom our global analyses due to the high number of nucle-otide ambiguities it contained. Clades 15 and 9 are pri-marily composed of environmental sequences fromanoxic or suboxic ecosystems (highlighted in grey inFig. 3). Both clades also include sequences retrievedfrom deep-sea methane cold seeps (DSGM-16 and 17,Takishita et al., 2007) and deep oceanic waters (Count-way et al., 2007), but these sequences were not includedin this analysis due to their short length. Clades originallycontaining only sequences from coastal systems (i.e.clades 2, 4, 5, 8, 12 and 13; see Groisillier et al., 2006) areshown here to also include clones from other oceanicregions, including oligotrophic waters. This highlights theimportance of gaining sequence representation from a

broader array of geographical locations. Finally, in termsof the number of sequences, the most commonly foundclades in rank order were clades 10+11, 7, 6, 1, 19, 3, 22and 16.

Other Syndiniales groups (III–V) also emerged from thepresent study (detailed in Fig. 1). Syndiniales Group IIIcontains 71 environmental sequences, including cloneOLI11005 (AJ402349) that was previously placed outsideGroup II (see Groisillier et al. 2006), as well as numerousenvironmental sequences retrieved from various oceanicsurface waters (Mediterranean Sea, Indian Ocean, Sar-gasso Sea), coastal waters [Southern Taiwan Strait,Blanes Bay (Spain) and the English Channel] and from asupersulfidic anoxic fjord (DQ310226). Syndiniales GroupIV contains the genera Syndinium and Hematodinium,five closely related environmental sequences, a sequenceretrieved from the Mediterranean Sea, E1–80m.27,closely related to Syndinium turbo and a clade allied withthe genus Hematodinium and composed of sequencesfrom the Sargasso Sea (EF172791 and DQ918583)and from deep sea hydrothermal vents (DQ504327 andDQ504356). Syndiniales Group V contains 67 environ-mental sequences, all collected within the euphotic zone,but includes clones retrieved from very different oceanicecosystems (Indian Ocean, Atlantic Ocean, Mediterra-nean Sea and Sargasso Sea). Sequence BL000921.23from Blanes also belongs to Syndiniales Group V (notincluded here due to sequence length dissimilarities).Finally, two partial environmental sequences could not beassigned to any specific group: EU793524 (E9–65m.123)and EU818559 (F14DEC+), but phylogenetic analysisplaced them closely related, although separated fromthese Syndiniales groups.

Ecological distributions

Dinoflagellate sequences represent less than 1% ofenvironmental sequences from continental ecosystems(aquatic and terrestrial), whereas they represent close to30% of the sequences obtained from marine ecosystems.With respect to aquatic environments (both marine andfreshwater), dinoflagellates sequences as a whole wereobtained primarily from the plankton, as opposed to otherenvironments such as sediments (Table 2). Sequencesbelonging to Syndiniales groups I and II were absent insamples collected to date from continental ecosystems,however, they represent the largest portion of dinoflagel-late sequences from marine systems. Syndiniales GroupII alone represented about half of all environmentaldinoflagellate sequences (Table 2).

We divided marine ecosystems included in oursequence database into various categories: (i) anoxic andsuboxic ecosystems, (ii) ecosystems with hydrothermalactivities, (iii) sediments, or (iv) the water column



(wherever possible, we also specified whether sequenceswere derived from the aphotic or euphotic zone; Fig. 4). Incases where these categories overlapped (e.g. anoxicsediments collected from deep hydrothermal vents, oranoxic water columns), environmental sequences wereincluded in both categories. Considering all dinoflagellatesequences, Syndiniales Group II sequences were moreabundant in clone libraries derived from the water column(planktonic ecosystems) than in other habitats, whilethe relative importance of the remaining dinoflagellatesequences (including Syndiniales Group I) was greater inanoxic environments, hydrothermal vents and sediments(Fig. 4). Within planktonic ecosystems, the relative contri-bution to clone libraries of Syndiniales Group I and IIcompared with other dinoflagellate sequences was similarbetween euphotic and aphotic waters (Fig. 4).

Environmental sequences derived from the euphoticzone, both coastal and oceanic waters, have generallybeen recovered using three different primer setsEuk328/Euk329, EukA/EukB and EukA/EukB′ (for primerreferences see Table S2). Although the contribution ofdinoflagellate sequences to the total number of clones is

very similar using either the EukA/EukB or EukA/EukB′primer sets, the relative contribution of Group II is higherusing the Euk328f/Euk329r primer set (Fig. 5). However,the distribution of Syndiniales Group I and II cladeswithin the euphotic zone, as evidenced from these clonelibraries, is quite similar with the different primer sets(Fig. 6). According to clone library composition, sunlitsurface marine waters are dominated by SyndinialesGroup I clades 1, 4 and 5, and Group II clades 1, 6, 7and 10+11 (Fig. 6). Comparing sequences obtainedusing the same primer sets, Syndiniales clade distribu-tions within the aphotic zone are quite different fromsurface waters, mainly dominated by Syndiniales GroupI clades 1, 2 and 3 and by Syndiniales Group II clades6 and 7 (Fig. 6).

Discussion

Our phylogenetic analysis of available 18S rRNA genesequences from described par

widespread occurrence and genetic diversity of marine...

Documents