Invasive Species

1. Invasive Species

2. "We must make no mistake: We are seeing one of the Great historical convulsions in the world's flora and fauna. We might say, with Professor Challenger, standing on Conan Doyle's 'Lost World', with his black beard jutting out: 'We have been privileged to be present at one of the typical decisive battles of history‑‑the battles which have determined the fate of the world.'" C. S. Elton, The Ecology of Invasions by Plants and Animals, 1958

3. Invasive problems in the U.S.Lodge et al. • kudzu (Pueraria lobata) in the SE U.S. • cheat grass (Bromus tectorum) in western U.S. crops and rangelands • zebra mussel (Dreissena polymorpha) in the Great Lakes region • the seaweed caulerpa (Caulerpa taxifolia) • Asian longhorn beetle (Anoplophora glabrapennis) • emerald ash borer beetle (Agrilus planipennis) • sudden oak death (Phytophthora ramorum) • Viruses: West Nile, monkeypox, and SARS

4. Melaleucain S Florida • Transpiration higher • Lower water table • Hotter fire • Deeper burn in organic matter, more severe effects

5. Economic & other impacts to human well-being • Forestry, agriculture • Boating, fishing, swimming, water supply • Allergies, toxins • Fire: human life and property • Cost of control • Environmental cost of toxic chemical use

6. Where did the invasive species problem come from? • Why is the earth a loaded gun of biological invasions waiting to happen?

8. Darwin (1859): In considering the distribution of organic beings over the face of the globe, the first great fact which strikes us is that neither the similarity nor the dissimilarity of the inhabitants of various regions can be wholly accounted for by climatal and other physical conditions… There is hardly a climate or condition in the Old World which cannot be paralleled in the New…[yet] how widely different their organic productions!

9. Summary 1: Separate evolution in separate places A global potential for invasion Darwin: Why separate creation for separate deserts

10. Is MORE SPP a problem?

11. The Homogocene’s Biodiversity Equation When does 1+1 not equal 2? Native Spp Alien Spp Total Comment/example 1 + 1 = 2 Complementarity Daylilies? 1 + 1 = 1 Competition Japanese honeysuckle? 1 + 1 = <1 Changed process Melaleuca in Florida Myrica in Hawaii

12. Where did the invasive species problem come from? Part 2

13. Darwin (1859): There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair. The elephant is reckoned the slowest breeder of all known animals...[yet] after a period of from 740 to 750 years there would be nearly nineteen million elephants alive, descended from the first pair.

14. 20,442 worlds of Paulownia “Walker counted the seed in a Paulownia pod and found ‘almost exactly 2,000’. He estimated the number borne on the trees as over 21 million. If each developed into a plant, which produced the same number of seeds the next generation, in the third generation there would be plants enough to cover 20,442 worlds the size of ours (American Forestry 25: 1486. 1919). Coker and Totten, Trees of the Southeastern States, 1945.

15. LOSSES: THE ROLE OF NATURAL ENEMIES Douglas fir seeds --after Lawrence & Rediske 1962 100 Seeds dispersed 47 At germination 21 3 month old seedlings 8 One year old individuals

16. Where did the invasive species problem come from?Summary 1 & 2 • Evolution in isolation producing adapted species which are unable to reach all appropriate sites • All species can increase exponentially

17. THEREFORE the potential for invasionsis clear • BUT NOT ALL SPECIES ARE INVASIVE • CAN WE EXPLAIN AND PREDICT INVASIONS? • AN OUNCE OF PREVENTION IS WORTH A POUND OF CURE…

19. What does science tell us about invasions and how might we use that information in prevention? 5 invasion hypotheses • 1a-d. Innate biology: Weediness, competitiveness, tolerance, preadaptation • 2. Enemy release/Biotic resistance • 3a-c. Community invasibility: diversity, productivity, disturbance • 4. Availability • 5. Rapid evolution of invasiveness

20. 2. Enemy release hypothesis (ERH)Biotic resistance hypothesis (BRH) Mitchell & Power 2003

21. Resources X Enemy ReleaseBlumenthal 2005. Science 310:243-244.

22. Digression: Asia as a source of invasive plants & diseases

23. Close taxonomic relationship has its own problems Specialized pests & diseases Chestnut blight, Dogwood anthracnose, Balsam & Hemlock woolly adelgids MANY OTHERS!

25. THE COEVOLUTIONARY HYPOTHESIS Bounded variation among enemies Persistence of the plant and its enemies results from a balance involving virulence, dispersal, and increase rate of the enemy AND defense, dispersal, and increase rate of the host Biological control tries to reestablish this coevolutionary context

26. What does science tell us about invasions and how might we use that information in prevention? 5 invasion hypotheses • 1a-d. Innate biology: Weediness, competitiveness, tolerance, preadaptation • 2. Enemy release/Biotic resistance • 3a-c. Community invasibility: diversity, productivity, disturbance • 4. Availability • 5. Rapid evolution of invasiveness

27. 5 invasion hypotheses:What to do 1a-d. Innate biology: Weediness, competitiveness, tolerance, preadaptation: SOME SPP ARE INVASIVE, PROHIBIT THROUGH RISK ASSESSMENT, DEVELOP STERILE CULTIVARS—YES 2. Enemy release/Biotic resistance: MANY SPP ARE INVASIVE, ESPECIALLY THOSE WITH HIGH GROWTH RATES AND HIGH RESOURCE DEMANDS, ASSESS ROLE OF ENEMIES—YES, but research is demanding 3a-c. Community invasibility: diversity, productivity, disturbance: SOME COMMUNITIES ARE INVASIBLE, MANAGE AGAINST INVASION, MANAGE AGAINST DISTURBANCE AND HIGH RESOURCE LEVELS, MANAGE FOR HIGH NATIVE RICHNESS—SOMETIMES, but not always feasible (disturbance, low richness, high resources are natural, too) 4. Availability: MOST SPP ARE INVASIVE, REDUCE AVAILABILITY—YES 5. Rapid evolution: RESTRICT GENETIC DIVERSITY—YES, but seems unlikely given horticultural interest in selection