Species invasion

Species invasion is a global problem. This tutorial slide just intends to summarize some of the invasion of global concern

1. Species invasion S. R. Maharjan Assistant Professor Tribhuvan University, Nepal 1 S.R. Maharjan

2. Native species are those that normally live and thrive in a particular community. They occupy specific habitats and have specific niches in their native environment. They have natural predators that help to keep their populations in check. 2 S.R. Maharjan

3. What is a non-native species?  A species living outside its native distributional range, which has arrived there by human activity, either deliberate or accidental.  Non-native species are not necessarily invasive. 3 S.R. Maharjan

4. An invasive species is one that arrives ( often with human assistance) in a habitat it had not previously occupied , then establishes a population and spreads autonomously. 4 S.R. Maharjan

5. The great majority of such invasions are by species introduced from elsewhere. For instance, for the Hawaiian islands, almost half the plant species, 25% of insects, 40% of birds, and most freshwater fishes are introduced. figures for Florida are 27% of plant species, 8% of insects, 5% of birds, and 24% of freshwater fishes. Not all introduced species become invasive. New Zealand had no native mammals, except for three bat species but now has 30 introduced mammals. 5 S.R. Maharjan

6. How are species introduced? Process of Invasion Unintentional pathways On any type of human transport such as airplanes,cars,ship ballasts Water ballasts New routes such as canals 6 S.R. Maharjan

7. Intentional pathways Species introduced intentionally for agriculture, aquaculture, recreation and ornamental purpose. Eg , german carp 7 S.R. Maharjan

8. Notable invasive species European starling house sparrow Phragmites purple loosestrife zebra mussel sea lamprey emerald ash borer

9. Invasive Species Some introduced deliberately: Ornamental plants game animals domestic animals Biological pests Some accidental: ballasts of ships unprocessed wood fruit shipments by-pass natural barriers 9 S.R. Maharjan

10. European starling Monk Parakeet Birds Mute swan 10 S.R. Maharjan

11. First successful introduction was 60 European starlings released in Central Park, NY. in 1890, European Starling competes with bluebirds, woodpeckers 11 S.R. Maharjan

12. The House Sparrow was introduced into Brooklyn, New York, in 1851. House Sparrow Competition from the House Sparrow for cavity nests can cause decline of some native species. 12 S.R. Maharjan

13. Insects Africanized Bees In 1956, African Honey Bees were imported into Brazil In 1957, 26 African queens escaped Reached US in 1990 More aggressive than European Honey Bees, have killed 1,000 people Impact honey and pollination industries 13 S.R. Maharjan

14. Insects Crop pests boll weevil, corn borer Culex mosquitos carry avian malaria and pox driven 20 Hawaiian bird species extinct Adult boll weevil 14 S.R. Maharjan

15. Insects Asian Long-horned Beetle attacks and kills many native trees Found in Chicago in 1998 15 S.R. Maharjan

16. Gypsy moth Introduced in 1860s Originally brought to the US for silk production now defoliates entire forests Insects 16 S.R. Maharjan

17. Brown Tree Snake Reptiles and Amphibians Introduced to Guam via cargo transported by U.S. military ships during World War II On Guam wiped out 9 of 13 indigenous bird species 17 S.R. Maharjan

18. Plants Kudzu kills other plants by smothering them under a solid blanket of leaves Introduced into the U.S. in 1876 promoted as a forage crop and an ornamental plant until 1953 18 S.R. Maharjan

19. Plants Garlic mustard Buckthorn garlic mustard outcompetes native plants by modifying light, moisture, nutrients, soil and space. Not as good food for herbivores as many native species poses a severe threat to native plants and animals 19 S.R. Maharjan

20. Negative effects on native clams Zebra mussels cover them and prevent them from feeding and moving 20 S.R. Maharjan

21. Characteristics of invasive species general diet and habitat requirements high abundance small body size good competitors social / gregarious Have few natural predators, parasites or diseases Have high reproductive rates Are long-lived Are pioneer species 21 S.R. Maharjan

22. Characteristics of invasive plant Self-compatible Flower early Produces abundant seed Disperse seed widely Grow rapidly Spread asexually Strong competitors 22 S.R. Maharjan

23. Impacts of invasive species 23 S.R. Maharjan

24. Ecosystem modification the physical structure of the habitat can be changed. Introduced plant species can modify an entire ecosystem by overgrowing and shading out native species. introduction of a few North American beavers (Castor canadensis ) in 1946 has have converted forests of southern beech ( Nothofagus spp.) to grassland In Florida , introduced Australian paperbark ( Melaleuca quinquenervia ) trees converted Grassand to forests In parts of Hawaii, Asian and American mangrove species have replaced beach communities to mangroove forests 24 S.R. Maharjan

25. South American water hyacinth ( Eichhornia crassipes ) now covers parts of Lake Victoria in Africa ,many lakes and rivers in the southeastern United States and various waterbodies in Asia and Australia. Vast quantities of rotting water hyacinth, and consequent drops in dissolved oxygen, can also affect many aquatic animal species.). 25 S.R. Maharjan

26. Introduced species can change entire ecosystems by changing the fire regime by modifying water or nutrient regimes. in Israel, Australian eucalyptus trees were deliberately introduced to drain swamps 26 S.R. Maharjan

27. Resource competition In Great Britain, the introduced North American grey squirrel forages for nuts more efficiently than the native red squirrel leading to the decline of the latter species The house gecko ( Hemidactylus frenatus ) from Southeast Asia and parts of Africa has invaded many Pacific islands, lowering insect populations that serve as food for native lizards, whose populations have declined in some areas 27 S.R. Maharjan

28. Aggression and its analogs The red imported fire ant ( Solenopsis invicta ) and The Argentine ant from southern South America attacks other ant species and great declines in populations of native ant species ( Tschinkel 2006). The zebra mussel spreading throughout much of North America, threatens the very existence of a number of native freshwater bivalve species, 28 S.R. Maharjan

29. Some invasive plants inhibit other species, by producing chemicals . For example, the African crystalline ice plant sequesters salt, and when leaves fall suppress other species in higher salt concentrations Diffuse knapweed ( Centaurea diffusa ) from Eurasia and spotted knapweed (C. stoebe ) from Europe are both major invaders of rangelands in America as that they produce toxic root exudates 29 S.R. Maharjan

30. Root exudates of garlic mustard , which does not have mycorrhizal associates, are toxic to arbuscular mycorrhizal fungi found in North American soils. 30 S.R. Maharjan

31. Predation . Introduced rats, for example, have caused the extinction of at least 37 species and subspecies of island birds throughout the world. for eg . ( Rattus rattus ), Norway rat (R. norvegicus ), Pacific rat (R. exulans ), small Indian mongoose ( Herpestes auropunctatus ), and stoat ( Mustela erminea 31 S.R. Maharjan

32. The brown tree snake( Boiga irregularis ) introduced to Guam from New Guinea in cargo after World War II, has caused the extinction or local extirpation of nine of the twelve native forest bird species on Guam and two of the eleven native lizard species (Lockwood et al. 2007). 32 S.R. Maharjan

33. Herbivory Introduced herbivores can devastate the flora of areas lacking similar native species, especially on islands. Plant-eating insects have been successful in many biological control projects for terrestrial and aquatic weeds. However, occasionally, biological control introductions of herbivorous insects have devastated non-target native species. 33 S.R. Maharjan

34. Goats (Capra aegagrus hircus ) introduced to the island of St. Helena in 1513 are believed to have eliminated at least half of 100 endemic plant species before botanists had a chance to record them ( Cronk 1989). European rabbits ( Oryctolagus cuniculus ) introduced to islands worldwide have devastated many plant populations, often by bark-stripping and thus killing shrubs and seedling and sapling trees 34 S.R. Maharjan

35. in the United States, the Russian wheat aphid ( Diuraphis noxia ) caused US$600 million damage in just three years (Office of Technology Assessment1993). In forests of the eastern United States, the European gypsy moth ( Lymantria dispar ) caused a similar amount of damage in only one year (Office of Technology Assessment 1993). 35 S.R. Maharjan

36. Pathogens and parasites Many introduced plant pathogens have modified entire ecosystems by virtually eliminating dominant plants. Introduced plant parasites can greatly damage agriculture. For example, parasitic witchweed ( Striga asiatica ) 36 S.R. Maharjan

37. Hybridization If introduced species are sufficiently closely related to native species, they may be able to mate and exchange genes with them –a sort of genetic extinction. 37 S.R. Maharjan

38. Thank you 38 S.R. Maharjan