Genetic characterization of Zostera noltii in the Berre Lagoon

Caractérisation génétique des Zostera noltii de l'étang de Berre

Gabriele Procaccini1, Ilia Serra2, Guillaume Bernard3

1 Stazione Zoologica Anton Dohrn, Napoli, Italy2 Dipartimento di Ecologia, Università della Calabria, (CS) Italy3 Groupement d’Intérêt Public pour la Réhabilitation de l’étang de Berre - Berre l’étang, France

Subclass Alismatidae(Class Liliopsida)

• 4 lineages of ‘marine’ angiosperms

• More independent origins of hydrophyly

Seagrasses

Ecological services

Exporting organic materialProtecting the coastline raising the sediment levelHosting a diversified animal and plant community(nursery role and importance for fishery)

Vegetative reproduction Sexual reproduction

Seagrasses reproduce both sexually and asexually

The number of genetically different individuals (genotypes) in a populations depends from the relative

importance of sexual and vegetative reproduction.

Above sediment

Sediment level

Seagrasses vegetative spread

The identification of the individual can become very difficult, do to the mode of vegetative spreading

Seagrass Clonal Forms

Environmental conditions

High clonal diversityLow clonal diversity

Population connectivity

Understanding the genetic diversity of populations and their connectivity can shed light on the effects of environmental pressures on species

distribution and evolution

…disappear

?

…move

?…be plastic

?

Environmental change

Importance of genetic diversity

Z. noltii

Zostera noltii

Distribution and geographic structure

Sampling sitesTwo sites within l’étang de Berre: Delta de l’Arc (Arc) and Pointe de Berre (Ber) One site in the Gulf of CarteauOne site within the Brusc lagoonGenetic structure has been evaluated in relation to three Tyrrenhian sites:Livorno, Civitavecchia and Ischia Island

Aims: understanding genetic diversity and isolation of Z. noltii meadows within l’étang de Berre

Molecular markers: nuclear DNA microsatellite

Microsatellites

GAGAGAGAGAGAGAGAGAG

GAGAGAGAGAGAGAGAG

minus GA

allele 1

allele 2

Polimorphic

Codominant

Individual/specific genotyping

Species-specific

HeterozygousHomozygous

  N G G/N A/locusPrivate alleles

Car 40 39 0.975 4.111 11

Ber 40 32 0.8 4.000 7

Arc 40 23 0.575 2.889 2

Bru 40 37 0.925 2.778 6

Genetic diversity

0.88890.88890.46140.42520.4195Bru

0.88890.88890.55070.45190.4425Arc

0.88890.88890.47900.52370.5156Ber

0.77780.77780.48340.47830.4722Car

P(0.99)P(0.95)H. obs.H. n.b.H. exp.

Heterozygosity and inbreeding

High values in all four populations. No significant differences between observed and expected heterozygosity

Weir & Cockerham FIS= -0.04266 FIT= 0.22787 FST= 0.25946

Low inbreeding High population differentiation

Genetic diversity

  N G G/N A/locus Ho He

Car 40 39 0.975 4.111 0.4834 0.4722

Ber 40 32 0.8 4.000 0.4790 0.5156

Arc 40 23 0.575 2.889 0.5507 0.4425

Bru 40 37 0.925 2.778 0.4614 0.4195

  N G G/N A/locus Ho He

Liv 25 20 0.80 5.25 0.4878 0.6027

Civ 31 25 0.80 4.65 0.5150 0.5697

Advantage of heterozygotes?

Bru0,0000,1590,1720,196

Arc0,0000,0630,140

Ber0,0000,112

Car0,000

BruArcBerCar

Pairwise Population Fst

Lowest gene flow values

Gene flow

Principal Coordinates

Bru

Arc

Ber

Car

Coord. 1C

oo

rd.

2

Principle Coordinates (1 vs 2)

Axis 1

Axi

s 2

Car

Ber

Arc

Bru

Berre populations

Genetic structure

Berre Lagoon

Carteau

Brusc

AFC

Genetic structure

0%

20%

40%

60%

80%

100%

Car Ber Arc Bru

Assignment test

Only the two populations from the Berre lagoon exchange genotyes

Principal Coordinates

Coord. 1

Co

ord

. 2

Car

Ber

Arc

Bru

Liv

Civ

French populations

Italian populations

LivCiv

Principal Coordinates

Coord. 1

Co

ord

. 2

CarBerArcBruISLivCiv

Latitudinal cline

LivCivIs

Clustering reflects geographic positions

Conclusions

• Populations within the Berre lagoon, particularly Arc, have lower number of alleles and lower genotypic diversity in respect to the others. This is a potential problem for the persistence of the meadows.

• Heterozygosis is high in all populations. There are not signs of inbreeding suggesting that sexual reproduction is active within the lagoon.

Environmental conditions

High clonal diversityLow clonal diversity

• Populations within the Berre lagoon are isolated from the ones in the open sea, but closer to the Carteau population.

• A cline seems to be present between Brusc and the other three French populations, reflecting patterns of gene flow and suggesting preferencial sites for collection of genotypes in transplanting strategies

• Clustering among all populations reflects geographic positions.

Funding agencies

• Stazione Zoologica Anton Dohrn• Gipreb

Thanks to the SZN Molecular Biology Service for

the microsatellite analysis

Hans von Marées, 1873 – Fresco room, Stazione Zoologica Anton Dohrn

The work has been made possible thank to a collaboration between the Stazione Zoologica Anton Dohrn and

Gipreb

Thank you for your attention

Aknowlegements & collaborations