GENETIC FACTORS AFFECTING INVASION SUCCESS. Leena Lindström Centre of Excellency Biological Interactions University of Jyväskylä Finland

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1 GENETIC FACTORS AFFECTING INVASION SUCCESS Leena Lindström Centre of Excellency Biological Interactions University of Jyväskylä Finland

2 First International Union of Biological Sciences Symposia on General biology: The Genetics of Colonizing Species (Asilomar, California 1964) One of the things that was fortunately envisioned by the organisers of the conference was that there is no such thing as a sharp separation between genetics, ecology, the study of behavior, and still other ways of looking colonizers. I am sure every ecologist here realizes that he really ought to know more about genetics, and that in a way we should consider the genetics of his organisms as part of their ecology. In a similar fashion, the geneticists realize that they cannot truly understand many of the genetic phenomena accompanying colonization unless they study them on the background of the ecological situations, again demonstrating there is no clear division between these two fields. Ernst Mayr 1965

3 Retrospective analysis: Invasion biology Elton 1958 The Ecology of Invasions by Animals and Plants: Baker & Stebbins (eds)1965 The Genetics of Colonizing Species It is not just the nuclear bombs and wars that threaten us, though these rank very high on the list at the moment: there are other sorts of explosions, and this book is about ecological explosions. The purpose of this symposia is to discuss, in terms of evolutionary theory, the situations which have arisen from the introduction of plants and animals from one part of the world to another. These transplantations of species have, in effect, been a series of experiments in evolution. As such, they are potentially much more informative than most laboratory experimental work, since they have faced the introduced species, not with some simple defined change in selective conditions, but with a whole new ecological system in which the species has to find a place for itself.

4 Alien species: Ecological perspective 1. Started from the need to protect nature (aliens, invaders, etc.) 2. A search for shared ecological characteristics of invaders in order to predict possible candidates 1. High fecundity 2. Short generation time 3. Resistant to environmental stress 3. Problem that our understanding is based on successful invasions 1. Only a fraction of all invasions succeed (varies among groups)

5 Alien species: Evolutionary perspective 1. Started from the need to understand colonization success in relation to genetic factors 2. Also the focus has been to study selection in action

6 How to build a more sustainable integrated pest management? Is to understand how the pest species adapt to novel environments Ecology! Human mediated changes! Most current data from retrospective analysis! Genetic architecture!

7 Opuntia cactus in South Africa

8 Established in close vicinity PPREVENTION Migration / Survival Population size Ecology & Evolution Establish in new area ERADICATION Lag period Time Spread CONTROL/ RESTORATION Ecological impact Human impact Sakai et al. 2001

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10 Invasion paradox (genetic paradox) Initially small populations = Loss of genetic variation f Population size Leimu et al. 2006: Journal of Ecology

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12 2 4 10% 20% 10 experimental areas Arytainilla spartiophila Broom Psyllid Released different Nro of individuals And followed the populations for 5 years 20% 50% % 80% 5 experimental areas Memmott, et al The effects of propagule size on the invasion of an alien insect. J. Anim. Ecol. 74:

13 Population bottlenecks or multiple introductions? - Founder effects +/- Multiple introductions Native Introduced

14 Nature 2004:431: Anolis sagrei, brown anole

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17 As the West has realized that they are weak in the warfare they have taken stronger weapons in the Cold war and employed biological warfare. Proof of this is the spreading of the Colorado potato beetles to the German Democratic Republic. Propaganda leaflets distributed in East-Germany (1950s-1960s)

18 Neutral genetic variability and origin of European Colorado potato beetle populations Invaders in 2002 mtdna : US >> Europe (20 haplotypes vs 1 haplotype) Heterozygosity level: US >> Europe (He 0.22 vs 0.18) Grapputo et al. 2005, Mol. Ecol.

19 Meta-analysis: 80 species native vs. introduced Dlugosch and Parker Molecular Ecology 17: Loss of genetic variation

20 One explanation for the invasions: some invaded ecosystems are rather simple ecological niches

21 ECOLOGY & CHANGES IN EVOLUTIONARY PRESSURES

22 Standing genetic variation When environment gets simple, maybe genetic variation is needed only in couple of traits ECOLOGY

23 Short cold summers Long winters SELECTION Shorter development time Economic energy use VARIATION HERITABILITY HIGH LOW CHANGE Potential to respond to selection Boman et al. 2008, Biol. Invasions 10: ; Piiroinen et al Func. Ecol. 25:

24 Heritable genetic variation is a necessity for adaptation Textbook: A population with many different alleles (i.e. higher genetic variation) may be better capable of dealing with changes in its surroundings. How to generate genetic variation? What is needed?

25 Spanish slug Hybridization Arion vulgaris European black slug Arion ater Cold tolerance?

26 Lucek et al Mol. Ecol Hybridization/admixture Switzerland Europe Hybridization=successful mating of two genetically distinct sources/populations resulting in genotypes with novel allele combinations Admixture= within population occurrence of individuals from multiple genetically distinct sources

27 Insect pest management has been part of agriculture over centuries And so has the insecticide resistance evolution Cumulative number of reported resistance to pesticides Colorado potato beetle resistant to over 50 chemicals YEAR Data from Whalon et al. 2008

28 Anthropogenically Induced Adaptation to Invade Hufbauer et al. 2011, Evol. Applications

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30 Colorado potato beetle invasion in summer 2002

31 ECOLOGY & CHANGES IN EVOLUTIONARY PRESSURES

32 Anthropogenically Induced Adaptation to Invade Selection for stress tolerance Mutagenesis Hufbauer et al. 2011, Evol. Applic.

33 Genetic factors and Pest Risk Assessment Genetic diversity is increased by multiple introductions from multiple origins Invasion routes and source populations become important Standing genetic variance All populations possess heritable variation, which may be realized in new environments Hybridization/admixture may increase the genetic variation Consider the potential to hybridize with native species Pest management strategies may increase the invasion to further new areas Engineering solutions are not the answer as we are shooting a moving target

34 First International Union of Biological Sciences Symposia on General biology: The Genetics of Colonizing Species (Asilomar, California 1964) One of the things that was fortunately envisioned by the organisers of the conference was that there is no such thing as a sharp separation between genetics, ecology, the study of behavior, and still other ways of looking colonizers. I am sure every ecologist here realizes that he really ought to know more about genetics, and that in a way we should consider the genetics of his organisms as part of their ecology. In a similar fashion, the geneticists realize that they cannot truly understand many of the genetic phenomena accompanying colonization unless they study them on the background of the ecological situations, again demonstrating there is no clear division between these two fields. Ernst Mayr 1965