Download The evolution of invasive ability

The evolution of invasive ability
Sébastien Lavergne
University of Vermont, Dept. of Botany
What is an invasive species ?
• A species that invades an habitat where it previously did not exist
before and grows without limit causing changes in the community and ecosystem
• Invasive Species vs. Alien Species
Alien species = a non-native species
Invasive species = alien species that harms communities and ecosystems
• Four stages necessary for a successful invasion :
1.
2.
3.
4.
Dispersal/transport to a new range
Initial colonization
Establishment (and lag phase)
Secondary spread
• Consequences of invasive species
Alter community composition and structure
Alter ecosystem structure, processes and function
Disease transmission
Large economic costs
What makes a species invasive when
translated into a new region ?
Sakai et al. (2001) Ann. Rev. Ecol. Syst. 32: 305-332
Lloret et al. (2005) J. of Ecology 93: 512-520
• Characteristics of the recipient community
- disturbance frequency
- resource availability and fluctuation
- species / functional diversity
• Traits of invasive species
-
sexual and asexual reproduction
rapid growth, and short time to maturity
long flowering / emergence period
good dispersal ability
good competitive ability / large size
… but recipient communities and alien species are not fixed entities…
Why studying evolution in invasive species ?
• Introduced species recently experienced a new environment, and therefore
new selective pressure.
-> A live experiment of natural selection
John N. Thompson 1998. Rapid evolution as an ecological process.
Trends in Ecology & Evolution, 13:8:329-332
Rapid evolution of interspecific interactions (during a time span of about 100 years) has the potential to be an
important influence on the ecological dynamics of communities. However, despite the growing number of
examples, rapid evolution is still not a standard working hypothesis for many ecological studies on the dynamics
of population structure or the organization of communities. Analysis of rapid evolution as an ecological process
has the potential to make evolutionary ecology one of the most central of applied biological sciences.
• Genetics processes likely to influence invasive species dynamics…
- genetic bottlenecks / genetic drift
- natural selection
- recombination / hybridization
Consequences of genetic bottlenecks on
introduced populations
• Loss of genetic diversity
native range
introduction
Binomial sampling (N, pt) linked to the dispersal / establishment phase
• Linkage (gametic) disequilibrium
native range
2 genes, 2 alleles per genes =
4 possible types of gamete
introduction
during a bottleneck, some combinations might be lost
and statistical association between alleles created
Bottlenecks in introduced ant populations
Tsutsui et al. (2000) Proc. Natl. Acad. Sci. USA 97: 5948-5953
Invasion of Argentine ants in California
Linepithema humile
Genetic diversity
Aggressive behavior with conspecifics
Introduced (California)
Native (Argentina)
H=0.204
H=0.639
no
yes
Bottlenecks in introduced plant populations
Eckert et al. (1996) Evolution 50(4): 1512-1519
Invasion of Lythrum salicaria
(purple loosestrife)
L
(ssmm)
S
M
(S---)
(ssM-)
• Mating is not possible between two individuals of the same type
(incompatibility within morphs => disassortative mating between morphs)
• The potential number of mates for one type in a population decreases with its
frequency (negative frequency dependence)
Bottlenecks in introduced plant populations
continued
Eckert et al. (1996) Evolution 50(4): 1512-1519
Invasion of Lythrum salicaria
(purple loosestrife)
Morph loss in ~5% of populations in
France vs. 23% in Ontario
Bottlenecks are not the rule of invasions
Kolbe et al. (2004) Nature 431: 177-181
Invasion of a Cuban lizard
Brown anole (Anolis sagrei)
Evolution of Increased Competitive Ability
EICA hypothesis
Blossey & Nötzold (1995) Journal of Ecology 83:887-889
Release from enemies allows selection from higher growth
selection
native range
growth
introduced range
-
-
defense
transport
no enemies
natural enemies
Evolution of Increased Competitive Ability
continued
Siemann & Rogers (2001) Ecology Letters 4:514-518
Invasion of Sapium setiferum (Chinese tallow tree)
Enemy release but no EICA
Genton et al. (2005) Oecologia 146:404-414
Invasion of Ambrosia artemisiifolia (common ragweed)
Novel weapons hypothesis
Another mechanism of EICA
Callaway & Aschebourg (2000) Science 290:521-523
Allelopathic effects on neighbors are stronger in the introduced range
introduced range
native range
naive community
- -
co-adapted community
-
transport
-
-
Novel weapons hypothesis continued
Callaway & Aschebourg (2000) Science 290:521-523
Invasion of Centaurea maculosa
(spotted knapweed)
Bais et al. (2003) Science 301:1377-1380
Evolutionary increase in reproductive vigor
Brown & Eckert 2005. American Journal of Botany 92(3):495-502
Invasion of Butomus umbellatus
(flowering rush)
Hybridization and evolution of invasiveness
Ellstrand & Schierenbeck (2000) Proc. Natl. Acad. Sci. USA 97(13):7043-7050
• Literature review : 28 well supported examples of invasive species that are
hybridized and which parent species are not invasive
• How inter-specific hybridization may catalyze the evolution
of invasive ability :
Species A
Species B
F1
segregation
recombination
translocation
recombination
translocation
chromosome
doubling
*
*
Increased variation
Evolutionary
Purge of
novelty
genetic load
Fixed heterosis
Hybridization and evolution of invasiveness
continued
Gaskin et al. (2002)
Proc. Natl. Acad. Sci. USA 99:11256-11259
Invasion of Tamarix spp.
Evolution of resistance to invasive species?
Callaway et al. (2005) Journal of Ecology 93:576-583
Tolerance of native American plant
species to allelo-chemicals of
Centaurea maculosa
The evolution of invasive ability
Conclusions
• Invasiveness may be a trait that has evolved after establishment of
alien species rather than a pre-adaptation
-> limited power of predictive approaches from species traits in their native range
• Template for evolution of invasive ability:
- bottlenecks and creation of new genetic structure in populations
- multiple introductions that increase local genetic diversity
- recombination between genetically distinct genotypes (or hybridization
between distinct species) can create novel genotypes