Population structure in Mycelis muralis (Sweden) - Stephanie Chauvet

Bill. (8). 10. 3.3 (1-5). 0.61 (0.27). 0.05 (0.09). 0.93. Bön. (6). 7. 1.8 (1-3). 0.38 (0.31). 0. 1.00. Eng. (8). 8. 1.7 (1-2). 0.35 (0.23). 0.05 (0.15). 0.95. Fler. (7). 11.
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Population structure in Mycelis muralis (Sweden)

Stéphanie Chauvet & Barbara Giles Umeå University and Groningen University

THE NATURAL CONTEXT

Natural landscape is a complex mosaic of habitats, due to: ÀBiological diversity and complexity ÀHabitat fragmentation by human activity

THE NATURAL CONTEXT

Natural landscape is a complex mosaic of habitats, due to: ÀBiological diversity and complexity ÀHabitat fragmentation by human activity Specific habitat and resource requirements: ÀSuitable and unsuitable habitats ÀFragmented distribution

THE NATURAL CONTEXT

Natural landscape is a complex mosaic of habitats, due to: ÀBiological diversity and complexity ÀHabitat fragmentation by human activity Specific habitat and resource requirements: ÀSuitable and unsuitable habitats ÀFragmented distribution ⇒ Population dynamics described by metapopulation models

METAPOPULATION DYNAMICS Time t

METAPOPULATION DYNAMICS Time t

Time t + 1

METAPOPULATION DYNAMICS Time t

Time t + 1

METAPOPULATION DYNAMICS Time t

Time t + 1

METAPOPULATION DYNAMICS Time t

Time t + 1

METAPOPULATION DYNAMICS Time t

Time t + 1

METAPOPULATION DYNAMICS Time t

Time t + 1

METAPOPULATION DYNAMICS 2 determinant parameters: ÀExtinction rate

ÀColonization rate (or dispersal rate)

METAPOPULATION DYNAMICS 2 determinant parameters: ÀExtinction rate - stochastic events - demographic parameters - successional stages ÀColonization rate (or dispersal rate)

METAPOPULATION DYNAMICS 2 determinant parameters: ÀExtinction rate - stochastic events - demographic parameters - successional stages ÀColonization rate (or dispersal rate) - dispersal ability - distance between populations - features of the landscape

DISPERSAL RATES

DISPERSAL RATES

DISPERSAL RATES

DISPERSAL RATES

Lower dispersal rate ⇒

Higher genetic differentiation

DISPERSAL RATES

Lower dispersal rate ⇒ Long distance seed dispersal ⇒

Higher genetic differentiation Colonization of isolated habitats

HYPOTHESIS TESTING

Genetic differentiation at local scale À distance isolation À effect of ”strict” isolation (by water) À effect of patch characteristics

HYPOTHESIS TESTING

Genetic differentiation at local scale À distance isolation À effect of ”strict” isolation (by water) À effect of patch characteristics Colonisation process of isolated habitat (islands) À genetic diversity on islands À number of founding events À origin of founders

STUDY SPECIES Mycelis muralis, Asteraceae: - ”dandelion” like, with a basal rosette of leaves - flowering stem with many capitula

STUDY SPECIES Mycelis muralis, Asteraceae: - ”dandelion” like, with a basal rosette of leaves - flowering stem with many capitula - five seeds per capitula

STUDY SPECIES Mycelis muralis, Asteraceae: - ”dandelion” like, with a basal rosette of leaves - flowering stem with many capitula - five seeds per capitula

Seed morphology: - wind dispersed

< 1 cm

STUDY AREA

Gävle region

coastal area island and mainland sites

LEAF COLLECTION (1)

21 sites: À 7 islands (

)

separated by insuitable areas

Gävle

À 11

mainlands ( )

separated by potential habitats

5 km

À 3 more mainlands (further north)

LEAF COLLECTION (2)

À samples size / site 30 < N < 300

Gävle

5 km

LEAF COLLECTION (2)

À samples size / site 30 < N < 300 À hierarchical sampling > site Gävle

>> patches >>> sub-patches

5 km

LEAF COLLECTION (2)

À samples size / site 30 < N < 300 À hierarchical sampling > site Gävle

>> patches >>> sub-patches À geographic location all sub-patches 5 km

LEAF COLLECTION (2)

À samples size / site 30 < N < 300 À hierarchical sampling > site Gävle

>> patches >>> sub-patches À geographic location all sub-patches 5 km

À habitat

descriptors

OPEN AND EXPOSED HABITAT

Island

Mainland

IN MIXED FOREST

Island

Mainland

IN CONIFEROUS FORESTS

Island

Mainland

IN BUSHES

Island

ALONG ROADS

Mainland

GENETIC ANALYSIS

Sample size: 20 individuals / 3 large islands 10 individuals / other populations (except 5 pop.) ⇒ N = 215

GENETIC ANALYSIS

Sample size: 20 individuals / 3 large islands 10 individuals / other populations (except 5 pop.) ⇒ N = 215

BUT: because of missing data ⇒ N = 147

GENETIC ANALYSIS

Sample size: 20 individuals / 3 large islands 10 individuals / other populations (except 5 pop.) ⇒ N = 215

BUT: because of missing data ⇒ N = 147 Preliminary results: - small sample sizes (allelic richness function of sample size) - missing resolution within site

GENETIC ANALYSIS

Sample size: 20 individuals / 3 large islands 10 individuals / other populations (except 5 pop.) ⇒ N = 215

BUT: because of missing data ⇒ N = 147 Preliminary results: - small sample sizes (allelic richness function of sample size) - missing resolution within site ⇒

Interpretation may change with increased samples

HYPOTHESIS TESTING

Genetic differentiation at local scale À distance isolation À effect of ”strict” isolation (by water) À effect of patch characteristics Colonisation process of isolated habitat (islands) À genetic diversity on islands À number of founding events À origin of founders

GENETIC ANALYSIS

Conducted for 11 microsatellites loci: Loc 4 → 4 alleles

Loc 16 → 9 alleles

Loc 5 → 8

Loc 20 → 6

Loc 6 → 16

Loc 21 → 6

Loc 7 → 8

Loc 22 → 4

Loc 9 → 7

Loc 24 → 7

Loc 12 → 10

MAINLAND SITES Bill. (8) Bön. (6) Eng. (8) Fler. (7) Flät (8) Kyrk. (8) Lind. (7) Löt. (4) Nötter. (9) Östan (6) S. Utv. (4) Såg. (4) Utv. (4) Vast. (7)

Pol. Loc. Bill. (8)

10

Bön. (6)

7

Eng. (8)

8

Fler. (7)

11

Flät (8)

9

Kyrk. (8)

9

Lind. (7)

8

Löt. (4)

2

Nötter. (9)

10

Östan (6)

8

S. Utv. (4)

6

Såg. (4)

7

Utv. (4)

4

Vast. (7)

9

Pol. Loc.

Nmd (range)

Bill. (8)

10

3.3 (1-5)

Bön. (6)

7

1.8 (1-3)

Eng. (8)

8

1.7 (1-2)

Fler. (7)

11

2.5 (2-3)

Flät (8)

9

2.0 (1-3)

Kyrk. (8)

9

2.3 (1-4)

Lind. (7)

8

1.8 (1-2)

Löt. (4)

2

1.3 (1-3)

Nötter. (9)

10

2.3 (1-3)

Östan (6)

8

1.6 (0-2)

S. Utv. (4)

6

1.6 (1-2)

Såg. (4)

7

1.7 (0-3)

Utv. (4)

4

1.3 (0-2)

Vast. (7)

9

2.4 (1-4)

Pol. Loc.

Nmd (range)

He (SD)

Bill. (8)

10

3.3 (1-5)

0.61 (0.27)

Bön. (6)

7

1.8 (1-3)

0.38 (0.31)

Eng. (8)

8

1.7 (1-2)

0.35 (0.23)

Fler. (7)

11

2.5 (2-3)

0.56 (0.11)

Flät (8)

9

2.0 (1-3)

0.47 (0.25)

Kyrk. (8)

9

2.3 (1-4)

0.48 (0.28)

Lind. (7)

8

1.8 (1-2)

0.41 (0.28)

Löt. (4)

2

1.3 (1-3)

0.13 (0.30)

Nötter. (9)

10

2.3 (1-3)

0.51 (0.21)

Östan (6)

8

1.6 (0-2)

0.33 (0.22)

S. Utv. (4)

6

1.6 (1-2)

0.27 (0.26)

Såg. (4)

7

1.7 (0-3)

0.36 (0.30)

Utv. (4)

4

1.3 (0-2)

0.19 (0.27)

Vast. (7)

9

2.4 (1-4)

0.46 (0.25)

Pol. Loc.

Nmd (range)

He (SD)

H0 (SD)

Bill. (8)

10

3.3 (1-5)

0.61 (0.27)

0.05 (0.09)

Bön. (6)

7

1.8 (1-3)

0.38 (0.31)

0

Eng. (8)

8

1.7 (1-2)

0.35 (0.23)

0.05 (0.15)

Fler. (7)

11

2.5 (2-3)

0.56 (0.11)

0.01 (0.04)

Flät (8)

9

2.0 (1-3)

0.47 (0.25)

0.01 (0.04)

Kyrk. (8)

9

2.3 (1-4)

0.48 (0.28)

0.06 (0.09)

Lind. (7)

8

1.8 (1-2)

0.41 (0.28)

0

Löt. (4)

2

1.3 (1-3)

0.13 (0.30)

0

Nötter. (9)

10

2.3 (1-3)

0.51 (0.21)

0.06 (0.11)

Östan (6)

8

1.6 (0-2)

0.33 (0.22)

0

S. Utv. (4)

6

1.6 (1-2)

0.27 (0.26)

0.03 (0.10)

Såg. (4)

7

1.7 (0-3)

0.36 (0.30)

0.09 (0.14)

Utv. (4)

4

1.3 (0-2)

0.19 (0.27)

0

Vast. (7)

9

2.4 (1-4)

0.46 (0.25)

0.01 (0.04)

Pol. Loc.

Nmd (range)

He (SD)

H0 (SD)

Fis

Bill. (8)

10

3.3 (1-5)

0.61 (0.27)

0.05 (0.09)

0.93

Bön. (6)

7

1.8 (1-3)

0.38 (0.31)

0

1.00

Eng. (8)

8

1.7 (1-2)

0.35 (0.23)

0.05 (0.15)

0.95

Fler. (7)

11

2.5 (2-3)

0.56 (0.11)

0.01 (0.04)

0.97

Flät (8)

9

2.0 (1-3)

0.47 (0.25)

0.01 (0.04)

0.95

Kyrk. (8)

9

2.3 (1-4)

0.48 (0.28)

0.06 (0.09)

0.88

Lind. (7)

8

1.8 (1-2)

0.41 (0.28)

0

1.00

Löt. (4)

2

1.3 (1-3)

0.13 (0.30)

0

1.00

Nötter. (9)

10

2.3 (1-3)

0.51 (0.21)

0.06 (0.11)

0.88

Östan (6)

8

1.6 (0-2)

0.33 (0.22)

0

1.00

S. Utv. (4)

6

1.6 (1-2)

0.27 (0.26)

0.03 (0.10)

0.92

Såg. (4)

7

1.7 (0-3)

0.36 (0.30)

0.09 (0.14)

0.82

Utv. (4)

4

1.3 (0-2)

0.19 (0.27)

0

1.00

Vast. (7)

9

2.4 (1-4)

0.46 (0.25)

0.01 (0.04)

0.97

ISLAND SITES Egg. (12) Gräs. (11) LH. (3) LR.(7) Löv. (14) N. Ä. (5) S. Ä. (5)

Pol. Loc. Egg. (12)

10

Gräs. (11)

8

LH. (3)

0

LR.(7)

11

Löv. (14)

11

N. Ä. (5)

9

S. Ä. (5)

6

Pol. Loc.

Nmd (range)

Egg. (12)

10

2.9 (1-4)

Gräs. (11)

8

1.9 (1-3)

LH. (3)

0

1.0 (1)

LR.(7)

11

2.6 (2-4)

Löv. (14)

11

3.1 (2-5)

N. Ä. (5)

9

2.2 (0-4)

S. Ä. (5)

6

1.5 (0-3)

Pol. Loc.

Nmd (range)

He (SD)

Egg. (12)

10

2.9 (1-4)

0.51 (0.20)

Gräs. (11)

8

1.9 (1-3)

0.25 (0.20)

LH. (3)

0

1.0 (1)

0

LR.(7)

11

2.6 (2-4)

0.58 (0.16)

Löv. (14)

11

3.1 (2-5)

0.57 (0.15)

N. Ä. (5)

9

2.2 (0-4)

0.44 (0.25)

S. Ä. (5)

6

1.5 (0-3)

0.30 (0.29)

Pol. Loc.

Nmd (range)

He (SD)

H0 (SD)

Egg. (12)

10

2.9 (1-4)

0.51 (0.20)

0.03 (0.04)

Gräs. (11)

8

1.9 (1-3)

0.25 (0.20)

0.02 (0.05)

LH. (3)

0

1.0 (1)

0

0

LR.(7)

11

2.6 (2-4)

0.58 (0.16)

0

Löv. (14)

11

3.1 (2-5)

0.57 (0.15)

0.03 (0.08)

N. Ä. (5)

9

2.2 (0-4)

0.44 (0.25)

0.02 (0.06)

S. Ä. (5)

6

1.5 (0-3)

0.30 (0.29)

0.02 (0.07)

Pol. Loc.

Nmd (range)

He (SD)

H0 (SD)

Fis

Egg. (12)

10

2.9 (1-4)

0.51 (0.20)

0.03 (0.04)

0.94

Gräs. (11)

8

1.9 (1-3)

0.25 (0.20)

0.02 (0.05)

0.90

LH. (3)

0

1.0 (1)

0

0

-

LR.(7)

11

2.6 (2-4)

0.58 (0.16)

0

1.00

Löv. (14)

11

3.1 (2-5)

0.57 (0.15)

0.03 (0.08)

0.95

N. Ä. (5)

9

2.2 (0-4)

0.44 (0.25)

0.02 (0.06)

0.96

S. Ä. (5)

6

1.5 (0-3)

0.30 (0.29)

0.02 (0.07)

0.94

Pol. Loc.

Nmd (range)

He (SD)

H0 (SD)

Fis

Egg. (12)

10

2.9 (1-4)

0.51 (0.20)

0.03 (0.04)

0.94

Gräs. (11)

8

1.9 (1-3)

0.25 (0.20)

0.02 (0.05)

0.90

LH. (3)

0

1.0 (1)

0

0

-

LR.(7)

11

2.6 (2-4)

0.58 (0.16)

0

1.00

Löv. (14)

11

3.1 (2-5)

0.57 (0.15)

0.03 (0.08)

0.95

N. Ä. (5)

9

2.2 (0-4)

0.44 (0.25)

0.02 (0.06)

0.96

S. Ä. (5)

6

1.5 (0-3)

0.30 (0.29)

0.02 (0.07)

0.94

Similar results for mainland and island sites: - high genetic diversity - high heterozygote deficiencies ⇒ M. muralis mainly reproduces by selfing

GENETIC DIFFERENTIATION BETWEEN SITES

À Calculated for all population pairs across all loci (210 pairs):

GENETIC DIFFERENTIATION BETWEEN SITES

À Calculated for all population pairs across all loci (210 pairs): - Genic differentiation:

significant for 206 pairs

- Genotypic differentiation: significant for 122 pairs

GENETIC DIFFERENTIATION BETWEEN SITES

À Calculated for all population pairs across all loci (210 pairs): - Genic differentiation:

significant for 206 pairs

- Genotypic differentiation: significant for 122 pairs

⇒ Allelic and genotypic distributions are highly structured across populations

GENETIC DIFFERENTIATION BETWEEN SITES All 21 populations

0.7

Fst

0.5

0.3

0.1

0

30

60

-0.1

Distances (km)

90

120

GENETIC DIFFERENTIATION BETWEEN SITES Mainland populations (14) 2

R = 0.1479 ; P = 0.004

0.7

Fst

0.5

0.3

0.1

0

30

60

-0.1

Distances (km)

90

120

GENETIC DIFFERENTIATION BETWEEN SITES Close mainland populations (11) 2

R = 0.1271 ; P = 0.004

0.7

Fst

0.5

0.3

0.1

0

5

10

15

-0.1

Distances (km)

20

25

GENETIC DIFFERENTIATION BETWEEN SITES

SUGGEST THAT GENE FLOW: Mainlands

⇒ affected by distance

Islands

⇒ rather function of founder events

GENETIC DIFFERENTIATION BETWEEN SITES

SUGGEST THAT GENE FLOW: Mainlands

⇒ affected by distance

Islands

⇒ rather function of founder events

HOWEVER...

GENETIC DIFFERENTIATION BETWEEN SITES À Accross different geographic zones:

Gävle

5 km

GENETIC DIFFERENTIATION BETWEEN SITES À Accross different geographic zones:

Gävle

North-East:

Fst = 0.32

South-East:

Fst = 0.16

Isolated islands: Fst = 0.32 Isolated mainlands: Fst = 0.31 5 km

GENETIC DIFFERENTIATION BETWEEN SITES À Accross different geographic zones:

Gävle

North-East:

Fst = 0.32

South-East:

Fst = 0.16

Isolated islands: Fst = 0.32 Isolated mainlands: Fst = 0.31 5 km

⇒ Founder effects are affecting all the populations...

INSULARITY EFFECT Expected effect 1: Lower genetic diversity on islands

Expected effect 2: Fewer rare alleles on islands

INSULARITY EFFECT Expected effect 1: Lower genetic diversity on islands ⇒ No (Mann-Whitney U-test non significant) Expected effect 2: Fewer rare alleles on islands

INSULARITY EFFECT Expected effect 1: Lower genetic diversity on islands ⇒ No (Mann-Whitney U-test non significant) Expected effect 2: Fewer rare alleles on islands N. of alleles

N. of alleles

16

16

Billan

12 8 4

Eggegrund

12 8 4 0

0

0.95

0.85

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

0.95

0.85

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

Vastänan

N. of alleles

N. of alleles

16 9 6 3 0

Lövgrund

12 8 4 0

0.95

0.85

Allele frequency

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

0.95

0.85

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

Allele frequency

INSULARITY EFFECT Expected effect 1: Lower genetic diversity on islands ⇒ No (Mann-Whitney U-test non significant) ⇒ No

Expected effect 2: Fewer rare alleles on islands N. of alleles

N. of alleles

16

16

Billan

12 8 4

Eggegrund

12 8 4 0

0

0.95

0.85

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

0.95

0.85

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

Vastänan

N. of alleles

N. of alleles

16 9 6 3 0

Lövgrund

12 8 4 0

0.95

0.85

Allele frequency

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

0.95

0.85

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

Allele frequency

AND SO...

À What affects gene exchange between populations ??? isolation, population size, habitat characteristics...

AND SO...

À What affects gene exchange between populations ??? isolation, population size, habitat characteristics...

À How are the genotypes distributed over populations ???