Phylogeography of the mysids Neomysis integer and Mesopodopsis slabberi

1
Phylogeography of the mysids Neomysis integer and
Mesopodopsis slabberi (Crustacea, Mysida) high
levels of molecular diversity and population
differentiation.
Remerie Thomas
2
Phylogeography - Molecular biogeography
John Avise (1987) A field of study concerned
with the principles and processes governing the
geographic distributions of genealogical
lineages, especially those within and among
closely related species.
3
Objectives
Examining the genealogical relationships and
distribution of molecular variation throughout
the majority of the Neomysis integer
Mesopodopsis slabberi geographical range.
Some questions addressed include
? How genetically cohesive are the species across
the European margins?

• Are there genetically differentiated,
  geographically distinct populations within its
  range?

? What are the patterns and pathways of gene flow
(dispersal)?
4
The species
mysid species (Crustacea, Mysida)
a ventral marsupium
Neomysis integer
Mesopodopsis slabberi
Typical brackish
Marine brackish
hyperbenthic low dispersal capacities
play a key role in marine ecosystems
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Methods
mtDNA cytochrome oxidase I (COI)
Single Stranded Conformation Polymorphism (SSCP)
DNA sequencing
Neomysis integer COI 447 bp Mesopodopsis
slabberi COI 520 bp
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Genetic differentiation of Neomysis integer
dd
11 sampling stations
Tvärminne - TV (41) Vistula - VI (41) Weser - WE
(39) Westerschelde WS (45) Ythan YTH
(39) East Looe EL (34) Kilkeran Lake Kilk
(42) Seine SEI (48) Gironde GI (43) Ria de
Aveiro RdA (29) Guadalquivir GU (40)
TOTAL n 441
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• 30 haplotypes
• h 0.8710 ? 0.0096
• 0.010254 ? 0.005582

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Neighbour Joining tree of Nei genetic distances
between populations based on haplotype frequencies
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Unique haplotypes
Shared haplotypes
AMOVA fst 0.800 (P lt 0.01) 80 among 20 within
populations
D-f
F-N19
F-g
E-e
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What caused this genetic differentiation?
NATURAL SELECTION
GENETIC DRIFT
MUTATION
Population genetic structure
GENE FLOW
historical patterns of gene flow shaped by past
climate events
Contemporary gene flow
The Pleistocene (1.6 Mya 10.000 ya) climate
oscillations glaciations/interglaciations
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? large consequences on species distribution and
played a major role in divergence and speciation
(Hewitt 1996, 2000)
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Reconstruction, 18.000 years ago (last glacial
maximum)
Ice sheet
Polar alpine desert
Steppe Tundra
Sealevel 120 140 metres lower than at
present (shorelines at the 150 metres contour)
Temperate woodland
Short-grass steppe
Contractions (glaciations) Survival in refugia
- Expansions (interglaciations)
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1) Isolation and survival in refugia
Mid Pleistocene
Mid Pleistocene
Mid Pleistocene
Early Pleistocene
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1) Isolation and survival in refugia
2) Range expansion from glacial refugia
??
??
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Genetic differentiation of Mesopodopsis slabberi
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Westerschelde
6

H27
H5
H3


Seine
2693
H30

6
Guadalquivir

H1


2692
2694
6

2691
Mondego

H21
H20

H17

H29

H2
H16

7

H22
Ria de Aveiro
H19
H4


H15
H14

Alicante

H18

7

7

Ebro
H9

H13
H23

H11

6
H24

H12
H10

6
H35

H7
H8

8

6
6
6
77

H6
H25


H32
H36
H34
H37
14.8
8

6.35

H26

• 47 haplotypes
• h 0.9947 ? 0.0058
• 0.057968 ? 0.028605

33

H28


H31
H33

72
73
H38
14
14


Mesopodopsis wooldridgei
H39
H43
H42

H41
H40
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Are we still talking about intraspecific
variation?
WS, SEI, MO A, RdA, GU 0.016 - 1.38
M. slabberi (Atl)
15.5
M. slabberi (Medit)
16.5
16.5
M. slabberi (Atl)
M. slabberi Mondego A
M. slabberi (Ebro Medit)
M. wooldridgei
M. slabberi Mondego B
M. slabberi (Alicante Medit)
M. wooldridgei
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Are we still talking about intraspecific
variation?
M. slabberi (Atl)
M. slabberi (Medit)
M. aegyptia ??
M. aegyptia
Wittmann Wirtz (1998)
Wittmann (1992) Taxonomical revision of the genus
Mesopodopsis
OR
Mediterranean M. slabberi lineage transported by
ship balast water??
M. tropicalis
M. wooldridgei
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Are we still talking about intraspecific
variation?
M. slabberi (Atl)
M. slabberi (Medit)
16.5
Large phylogeographic break!
Molecular clock 1.66 2.6 per My for
crustacean mtDNA
10 6 Mya (late Miocene)
Allopatric differentiation during the Messinian
salinity crisis? abscence of gene flow
cryptic species??
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NE Atlantic differentiation
AMOVA fst 0.396 (P lt 0.01) 39.6 among 60.4
within populations
Fst (nucleot. divergence)
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NE Atlantic Medit. differentiation
Fst (nucleot. divergence)
WS
SEI
RdA
MO
EB
700 km
0.96
0.45
GU
Ali
0.917
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Neomysis integer vs Mesopodopsis slabberi
mitochondrial COI 7 locations along NE Atlantic
Mediterranean
mitochondrial COI 11 locations along NE Atlantic

• 47 haplotypes (n55)
• h 0.9947 ? 0.0058
• 0.057968 ? 0.028605
• hATL 0.9974 ? 0.0063
• ATL 0.017396 ? 0.009086

• 30 haplotypes (n441)
• h 0.8710 ? 0.0096
• 0.010254 ? 0.005582

Low intrapopulation variation
High intrapopulation variation
fst 0.396 (P lt 0.01) 39.6 among 60.4 within
populations
fst 0.800 (P lt 0.01) 80 among 20 within
populations
0.22 4.02
0.19 3.4 and up to 16.5 (Ebro)
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Neomysis integer vs Mesopodopsis slabberi
? Due to species-specific differences in
physiological tolerances and habitat preferences??
hyperbenthic
hyperbenthic/pelagic
brackish water mysid discrete, estuarine habitats
coastal, surfzone estuarine mysid more
continuous habitat ?
Large heterogeneity of habitats higher degree
of polymorphism diversity ?
Common genetic characteristics of brackish-water
species ! Cognetti Maltagliati 2000 Bilton 2002