Download Rapid evolution and speciation in a marginal environment

TWO BASIC PREMISES:
Rapid evolution and speciation
in a marginal environment
1. Natural selection can drive adaptive divergence on ecological
time-scales "CONTEMPORARY" OR "RAPID" EVOLUTION (<100
GENERATIONS)
2. Adaptive divergence can lead to reproductive isolation
PREDICTION:
Adaptation to new environments can cause the contemporary
evolution of reproductive isolation
Via 2009
Butlin et al. 2011
Nosil et al. 2008
Anthoxanthum odoratum
Euhrychiopsis lecontei
Oncorhynchus nerka
Via 2009
Hybrid speciation: Hybrids may sometimes land on
new adaptive peaks exploiting new environments
that parental species cannot.
Antonovics & Bradshaw 1970
Sheldon & Jones 2001
Hendry et al. 2000
1
Lycaeides spp.
Gompert et al. 2006
The low saline Baltic: an extreme environment for marine species
The low saline Baltic: an extreme environment for marine species
Peripheral pop
Species
distribution
Central population
Marginal pop
Different environmental
conditions
Reduced connectivity
Different selection pressures
Reduced sexual reproduction
Reduced gene flow
Increased genetic drift
1. Loss of genetic variation
2. Genetically divergent
from central populations
Baltic populations
more diverse than
North Sea populations
Divergent Baltic populations
Baltic populations
less diverse than
North Sea populations
0.6
Genetic distance to reference population
A. No differentiation
1.0
Allozyme
Microsatellite
0.8
mtDNA
RAPD
X=Y
0.6
0.4
B. Isolation-by-distance
1
C. Peripheral perturbation
4
D. Atlantic-Baltic genetic shift
4
0.5
Genetic distance
0.5
Genetic diversity of species X in Baltic pops
0
11
0.4
Cod
Eelpout
Blue mussel
Macoma baltica
0.3
ltic
Ba
0.2
rt
No
0.1
ea
hS
0
Geographic distance to Baltic entrance (dashed line)
0.2
20 species
0.0
0.0
0.2
0.4
0.6
0.8
-2000
-1000
0
1000
2000
3000
Distance from Öresund (km)
1.0
Genetic diversity of species X in North Sea pops
From Johannesson & André 2006
From Johannesson & André 2006
2
CASE STUDY:
Fucus vesiculosus & F. radicans
in the Baltic Sea
LIFE IN THE BALTIC SEA FOR Fucus
SPECIES
•F. radicans smaller (dwarf) with
NORTH SEA TIDAL
EXPOSED TO DESICCATION
narrow thalli and bushy
appearance.
•F. radicans distributed in the
Baltic; F. vesiculosus Arctic &
temperate regions
•Produce important complex
structure & feeding habitat for
other species
•MtDNA and ITS sequences
unable to discriminate both
species
LIFE IN THE BALTIC SEA FOR Fucus
SPECIES
BALTIC CONSTANTLY
SUBMERGED
Serrao, 1996
•F. radicans AND BALTIC F. vesiculosus
SPERMS SWIM FASTER THAN SWEDISH
WEST-COAST AND ICELANDIC F. vesiculosus
SPERMS AT LOW SALINITIES
COVERED BY ICE
AT LOW TIDE
LOW LIGHT
CONDITIONS
•F. radicans AND BALTIC F. vesiculosus
PERFORM BETTER AT 10 AND 5 PSU
POTENTIAL MECHANISMS OF FUCUS DISPERSAL
IN THE BALTIC SEA
Modified from Tatarenkov, 2005
INTERSPECIFIC DIFFERENCES BY LOCALITY
PCA MORPHOLOGY
PuuliPanki Fradicans
PuuliPanki Fvesiculosus
Trigii Fradicans
Kõiguste Fvesiculosus
Djursten Fradicans
Djursten Fvesiculosus
Bönhamn Fradicans
Bönhamn Fvesiculosus
ESTONIA
White Sea
2
Norwegian
Sea
F. radicans F. vesiculosus
1
13.4%
SWEDEN
3
0
-4
-3
-2
-1
0
1
2
3
4
Gulf of
Bothnia
5
lan
f Fin
lf o
Gu
-1
-2
42.92%
-3
ag
Sk
d
ak
err
North
Sea
Baltic
Proper
100 km
Pereyra et al. in prep
3
PROPORTION OF SEXUAL vs ASEXUAL REPRODUCTION
(CLONALITY DISTRIBUTION)
Individuals with identical genetic identity (Clones)
F. vesiculosus
SWEDEN
F. ves FIN
F. radicans F. radicans
SWE-FIN
ESTONIA
F. ves
ESTONIA
F. vesiculosus
FINLAND
F. radicans
SWEDEN
97
Fr
ad
SW
E
(SW DEN
E)
Fv
FINLAND
(FIN)
F. radicans
FINLAND
64
F. vesiculosus
SWEDEN
Fv
F. radicans
ESTONIA
82
Frad
Fv
F. vesiculosus
ESTONIA
0.1
F. radicans
F. vesiculosus
Johannesson et al. 2011
...BUT,WHERE DID ALL START FOR Fucus radicans??
III
OB
F. radicans
J
Järnäs
NW Gulf of Bothnia
III
Fv White Sea (Russia)
I
WHITE SEA
IN
SU
L
PE
N
ARCTIC
ORIGIN?
AN
AV
I
IN
I
F. radicans
II Öregrund
SW Gulf of Bothnia
II
F. vesiculosus
Öregrund
IV
SW Gulf of Bothnia
Fv Öland Baltic proper
D
LAN
IN
ak
err
BALTIC
PROPER
2 SPECIES PREVIOUSLY DIVERGED
-POSTGLACIAL COLONIZATION
FROM NORTH SEA?
100 km
... OR RECENT
ORIGIN
WITHIN THE
BALTIC SEA?!!!
0.12
0.1
POSTERIOR
PROBABILITY
SC
AN
D
ag
IV
0.1
GULF OF
BOTHNIA
FF
Sk
99
Fv Norway
Fv Lysekil Skagerrak
O
LF
GU
NORTH
SEA
91
72
A
NORWEGIAN
SEA
0.08
0.06
0.04
0.02
0
0
1500 3000 4500 6000 7500 9000 10500
TIME OF SPECIES DIVERGENCE (YEARS)
Pereyra et al. 2009
APPROACHES THAT MIGHT REVEAL SIGNATURES OF RAPID
EVOLUTION
•Test whether individuals in new environments 'prefer' those new environments,
a tendency that will reduce dispersal between new and ancestral environments
•Use reciprocal transplants among similar and different environments and look at
survival and reproductive success of transplanted individuals.
•Examine the mate preferences of reproductively active males and females from
similar and different environments.
•Consider the effect of multiple reproductive barriers by testing whether gene flow
is lower between populations in different environments than between populations in
similar environment
4