Introduced Species Introduction of exotic species to new areas can be the result of: Deliberate actions, ignorance of consequences, or for control of other species Accidental, unknown carriers bring species to new area Natural, rarer, species naturally disperse to new areas

Natural introduction: Cattle egret, only species to have reached all 7 continents From Africa, reached Brazil in 1930s, Florida in 1940s, now widespread in Southeast

Accidental: Whitefly ‘superbug’ Introduced in Florida in 1980s on poinsettias Attack 500+ crop plants; killing stunting growth Deposit sticky residue that allows mold to grow Spread viruses among crops Congregate under leaves, out of harm from pesticides Introduced in Florida in 1980s on poinsettias, attacks 500+ crop plants sucking juices from fruit, leaves, stems. Kill or cause stunted growth, congregate under leaves out of harm from pesticides, resistant to most pesticides, deposit sticky residue on fruit and leaves that allows mold to grow, transmits diseases (viruses) to different crops, problem in fields and greenhouses.

Deliberate: Reindeer to sub-Antarctic Island, South Georgia

Deliberate: Reindeer to sub-Antarctic Island, South Georgia Introduced in early 1900’s by Norwegian whalers Reindeer adapted well to climate, new food, and reproduced 1st of 3 introductions in 1909, by 1958: 3,000 animals Arctic density 5-7/km2, South Georgia approaches 40-85/km2 Severe overgrazing: soil erosion, loss of plant biodiversity, loss of nesting habitat for birds http://english.ohmynews.com/articleview/article_view.asp?menu=c10400&no=365216&rel_no=1

Deliberate: Kudzu -- Kudzu vine introduced to U.S. in 1876 at the Philadelphia Centennial Exposition -- Plantings in southeast encouraged to prevent soil erosion, as a forage plant, and ornamental until listed as pest species in 1953 -- Rapid growth: 60 feet/season or ~1 foot/day Kill trees and plants by smothering them, or weight breaks them down www.firehow.com

Keystone exotics Species that change entire community structure In Southeast, Honeysuckle and Kudzu smother native forests http://www.treehugger.com/renewable-energy/biofuel-feedstocks-gain-a-new-candidate-kudzu.html http://www.ppws.vt.edu/scott/weed_id/lonja.htm

Keystone exotics Species that change entire community structure In Southeast, Honeysuckle and Kudzu smother native forests Hyacinths in Everglades

Keystone exotics Species that change entire community structure In Southeast, Honeysuckle and Kudzu smother native forests Hyacinths in Everglades Livestock—grazing in western US Once desert grassland, now gone

Erosion in New Mexico from 100+ yrs of overgrazing

Loss of cultural remains ~800 yrs old

Spotted Knapweed in western U.S and Canada --arrived from Europe to British Columbia as an accidental introduction\ --takes over large areas of open grassland --except for sheep, most grazing animals avoid it --produces an allelopathy to prevent other plants from growing around it

Most introductions fail Wrong ecological conditions for survival, can’t compete with natives (niches full) Egrets reached Antarctica, couldn’t survive there Warming trend may change conditions and some introductions could succeed

What factors allow for successful invasions? Small organisms do best. Rapid generations and r-selected reproduction Evolve and adapt to new conditions quickly 2) Easily transported, or not detected Small insects on plants, fungi 40% crop pests in US are insects Seeds on shoes can be carried long distances Ballast tanks on ships

What factors allow for successful invasions? 3) Favorable habitats present in new area May have fewer or no predators Acts as release from counteradaptations Islands particularly susceptible as often have more open niches, lower species diversity then mainland e.g., cats, goats, pigs, rats

Stephens Island Wren, New Zealand

Eradication Once a species becomes established, can be very difficult to eradicate % population remaining 100 Cost/effort to eradicate

Eradication: Biological controls Use natural predators from invaders home community Sometimes successful Australia introduced dung beetle to solve livestock dung and fly problem

Eradication with Genomics Genetic engineering: a new weapon Rabbits introduced in Australia being controlled by a manufactured virus, causes sterility Lots of experiments prior to release Unintended consequences—will virus mutate and spread to other native species?

The Infamous Cane Toad Native to South America Introduced to Australia in 1930s for biological control of cane grub Became part of local culture No natural predators, spread rapidly Impacts native wildlife with poison glands

Introduced Species examples: Know: 1) Why/how they were introduced 2) Why they are so successful 3) Why are they difficult to eradicate 4) Problems caused? Solutions? whitefly ‘superbug’ kudzu, honeysuckle, hyacinth, and knapweed as keystone exotics cane toad as deliberate introduction, biological control cattle egret as natural introduction