Intra-host speciation in theLamellodiscus ignoratusmorphotype?

Timothée Poisot • Olivier Verneau • Yves DesdevisesUniversité de Montpellier — Faculté des SciencesAugust 2008

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Monogeneans : gill parasites

Haptor

Anteriorsucks

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Monogeneans : gill parasites

Eggs

Larvae Active host

search

Haptor

Anteriorsucks

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Evolution of Lamellodiscus

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Evolution of Lamellodiscus

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Evolution of Lamellodiscus

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Evolution of Lamellodiscus

Cospeciation + intra-host speciation + … ?3

Hypotheses for Lamellodiscus evolution

• Host-switch followed by speciation

• Suggested for Gyrodactylus

• Thought important for Lamellodiscus

• Intra-host speciation

• Suggested for Dactylogyrus

• Yet to study for Lamellodiscus

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Methods

Haptor (fixation organ)

18S 5.8S[…]

ITS1

tRNA-Trp Cox1 tRNA-Thr 16S

Variable in size (≈1kb)

Desdevises et coll. 2000

Littlewood et coll. 1997

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Why the ignoratus morphotype?

L. ignoratus

L. neifari

L. confusus

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Why the ignoratus morphotype?

L. ignoratus

L. neifari

L. confusus

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−6 −5 −4 −3 −2 −1 0 1 2 3 4

−2.0

−1.5

−1.0

−0.5

0.0

0.5

1.0

1.5

2.0

2.5

Axe 1: 71.1 %

Axe

2: 8

.54

%

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Genetic similarity (%)

18S Its1 Cox1

L. ignoratus

L. neifari

Ignoratus-like

95,7 86 76

99,8 85 91

97,3 86 79

18S Mouse Chicken Xenopus Nematode

Human 99,2 96,4 95,9 87,1

18S

Mean (≠ species) : 94.3%

L. fraternus/L. ergensi : 99.4%

L. ignoratus/L. virgula : 94.3%

L. parisi/L. elegans : 90.8%

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18S rDNA (Maximum likelihood + Bayesian)

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18S rDNA (Maximum likelihood + Bayesian)Ignoratus

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Its1 (ML + Bayesian)

?

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Its1 (ML + Bayesian)Ignoratus

?

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Hypotheses

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Hypotheses

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Hypotheses

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Conclusions

•Genetic variability of Lamellodiscus is high

•Confirmed by new sequences (Cox1)

•Potential under-estimation of the real diversity of the genus

•The ignoratus morphotype

•“New” species are not genetically distinguishable

•Paraphyletic species, or greater diversity than expected?

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Thank you for your attention

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Cox1 : estimation of saturation

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Ti

Tv

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0.00 0.05 0.10 0.15 0.20 0.25

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Tv

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0.00 0.05 0.10 0.15 0.20 0.25

0.0

0.1

0.2

0.3

0.4

Ti

Tv

Triplet 1 & 2 3

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Principal components analysis

!6 !5 !4 !3 !2 !1 0 1 2 3 4

!2

.5!

1.0

0.5

1.5

L. elegans

Axe 1: 74.5 %

Axe 2

: 9

.28 %

!

!

!

!8 !7 !6 !5 !4 !3 !2 !1 0 1 2 3

!2

.5!

1.0

0.5

1.5

L. ergensi

Axe 1: 66.7 %

Axe 2

: 1

0.7

%

!

!

!

!6 !5 !4 !3 !2 !1 0 1 2 3 4

!2

.0!

0.5

1.0

2.0

L. ignoratus

Axe 1: 71.1 %

Axe 2

: 8

.54 %

!4 !3 !2 !1 0 1 2 3 4 5

!2

.5!

1.0

0.5

2.0

L. kechemirae

Axe 1: 54.5 %

Axe 2

: 1

5.3

%

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Ignoratus-like

L. neifari

L. falcus

L. ignoratus

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