Invasive species

„But the cardoon (Cynara cardunculus) has a far wider range.: it now occurs in these latitudes on both sides of

the Cordillera across the continent. I saw it in unfrequented spots in Chile, Entre Rios, and Banda

oriental. In the latter country alone, very many (probably several hundred) square miles are covered

with one mass of these prickly plants, and are impenetrable by man or beast. Over the undulating

plains, where these great beds occur, nothing else can live. Before their introduction, however, I apprehend

the surface supported as in other parts a rank herbage. I doubt whether any case is on record of an invasion of

so grand scale of one plant over the aborigines”

Charles Darwin 1839: Voyage of the Beagle.

What are invasive species?

Invasive species are those that• were accidently introduced into new habitats by

man (alien species) • were intentionally introduced into new habitats by

man for commercial purposes• were intentionally introduced into new habitats by

man for biological control• greatly extended their natural home ranges

towards new areas for instance due to climate change or human activities (roads, tunnels)

Some well known examples

Colorado Potato beetle Gipsy moth

First introduced to Europe in 1877

First record in Poland 1960First introduced into North America in 1868

Has about 650 different host plants

During outbreaks causes major damages in softwood forests

Tiger mosquito Nil perch

Introduced into the great Est African lakes during the 1950s and 1960s to improve fishering.

Caused dramatic changes in faunal and floral composition

Caused algal blooms and eutrophication

Caused the extinction of more than 200 native fish species (2/3 of all species)

The Asian species was first reported from Houston texas in 1985

Now established in Brazil, Europe, and New Zealand

Vectors of yellow and dengue fever, as well as encephalitis

Changing cimate will promote the spread towards northern countries

First occurrence in mainland France in 2006. Now recorded from Belgium, Italy, France, Balkan region. First deadly infection of Chikungunya feaver in Italy 2007.

Marenzelleria viridisEichhornia crassipes

Introduced into China from South America in the 1930s as an ornamental plant, to provide liestock food and to control air pollution

Caused reduction of lake areas and let to the extinction of about 30 fish species

Reduced lake areas caused climate changes and changes in water cycling

The flatworm was introduced via ship ballast water (first records 1979)

In the vistula lagoon it has become the dominant species constituting up to 97% of the total biomass of the bottom- living macrofauna

Harmonia axyridis

First observations of the Asian Lady beetle 2001: Belgium2002: Germany, Netherlands2004: UK, France2007: Scandinavia, Poland2009: Whole of Poland

In the USA unsuccessfully used as aphid predator in biological control programs since 1916.Sudden spread in USA since 1980.Major impact on natural communities of aphid predators due to its high reproduction rate.

Unknown harvestman (Opilionida) species

First observed in the Netherlands (2007)In 2008 massive invasion along the Rhine river up to Switzerland

Species are up to 18 cm in diameter.They occur in large colonize of up to several hundred individuals.They show colonial movements.

     Number of

native species  Number of

invasive species

New Zealand (plants) 1790 1570

Hawaii (plants) 956 861

Hawaii (all species) 17591 4465

Tristan de Cunha (plants) 70 97

Campbell Islands (plants) 128 81

South Georgia (plants) 26 54

Southern Africa (freshwater fish) 176 52

California (freshwater fish) 83 52

Berlin (plants)    839    593

Woody perennials (Southern Australia) 2230 188

Europe (spiders) 3500 80

Great Britain (trees)    35    1700

How many species are invasive?

Data from McNeely J. A. (1999), Kobelt and Nentwig (2008), Caley et al. 2008, and Sukopp (1990)

Air cargo39%

Miscella-neous

2%Mails3%

Baggage40%

Ship cargo16%

How do alien species come to Hawaii?

25% of all Hawaiian species are alien

Human activities

Disturbance

Changing environmental

conditions

Changing land management

Changing land use

Changing of ecosystem functioning

Invading species

Habitat fragmentation

Increasing opportunities for invaders

A conceptual model of invading species

What makes a species invasive?

Charcteristics of invasie species• r-strategists• have high dispersal ability• have small genome sizes• are habitat or feeding generalists• self pollinators (plants)• have long flowering periods (plants)• have a high proportion of leaf area (grasses)• have small seed sizes (in woody plants)• occupy often disturbed sites

Marcel Rejmanek (1946-

DNA contents of 148 Californian angiosperms (from Knight et al. 2005)

What habitats are susceptible to invasions?

• Early to mid-successional habitats

• Mesic environments and open water

• Disturbed habitats

• Fragmented habitats

Phylogenetic distance from the resident species

„...floras gain by naturalization, proportionally with the number of native genera and species, far more in new genera than in new species”

Charles Darwin 1959: The Evolution of Species by Means of Natural Selection

Number of European

species NOT naturalized in

California

Number of European species

naturalized in California

2

Poaceae shared genera 466 43 <0.0001European genera 257 69

Asteraceae shared genera 681 22 <0.0001European genera 762 66

Brassicaceae shared genera 230 12 <0.05European genera 342 36

The analysis of plant species introduced to California shows that significantly more species of European genera were naturalized

than of shared genera.

(from Rejmanek 1999)

Time lags

Trees  

Time lag

(years)   Shrubs  

Time lag

(years)

Robinia pseudoaacia 152 Mahonia acuifolium 38

Acer negundo 183 Syringa vulgans 124

Prunus serotina 29 Symphoricarpus albus 65

Aesculus hippocastanum 124 Philadelphus coronarius 183

Quercus rubra 114 Lycium barbarum 70

Ailanthus altissima 122 Cornus stolonifera 76

Populus canadensis 165 Lonicera tatarica 94

Prunus mahaleb 54 Ribes aureum 61

Laburnum anagryroides 198 Colutea arborescens 265

Salix intermedia 112   Cornus alba 84

From introduction to spreading might pass a long time.

Observed time lags from intyroduction to sprading in various trees and shrubs in the area of Berlin and Brandenburg (Kowarik 1995)

Invasive species: http://en.wikipedia.org/wiki/Invasive_species

Invasive species database: http://www.issg.org/database/welcome/

A different opinion: http://www.nytimes.com/2008/09/09/science/09inva.html

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