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Essay writing

Title of essay Please write a short paragraph why you write about the chosen topic. 5 citations (no annotation, yet)

Due date: in the week after springbreak

European Starling

The European starling was first introduced to the United States in New York City, in 1890. Inspired by William Shakespeare's plays, Eugene Scheffland let loose one hundred starlings in Central Park.

How invasives move/spread

Stow-aways Commerce/Curiosity Recreation Aesthetics Biological control

Cane toads in Australia

Cane toads were deliberately introduced to Australia from Hawaii in 1935 in an attempt to stop French’s Cane Beetle and the Greyback Cane Beetle from destroying sugar cane crops in North Queensland. The Australian Bureau of Sugar Experimental Stations made the release of 101 cane toads at Gordonvale in Queensland in 1935. They were unsuccessful in controlling the cane beetles. Biological control = Introduction of predators to control a prey species

Cane toads in Australia

Cane Toads - An Unnatural History (1987)

Invasion and the evolution of speed in toads

Benjamin L. Phillips1, Gregory P. Brown1, Jonathan K. Webb1 and Richard Shine1 Cane toads seem to have honed their dispersal ability to devastating effect over the generations. Cane toads (Bufo marinus) are large anurans (weighing up to 2 kg) that were introduced to Australia 70 years ago to control insect pests in sugar-cane fields. But the result has been disastrous because the toads are toxic and highly invasive. Here we show that the annual rate of progress of the toad invasion front has increased about fivefold since the toads first arrived; we find that toads with longer legs can not only move faster and are the first to arrive in new areas, but also that those at the front have longer legs than toads in older (long-established) populations. The disaster looks set to turn into an ecological nightmare because of the negative effects invasive species can have on native ecosystems1, 2; over many generations, rates of invasion will be accelerated owing to rapid adaptive change in the invader3, with continual 'spatial selection' at the expanding front favouring traits that increase the toads' dispersal4, 5.

How do invasives move/spread

Pattern of a “typical” invasion Latent phase (small population size) Rapid population growth and spread

Opuntia in South-Africa

Reconstructing 50 years of Opuntia stricta invasion in the Kruger National Park, South Africa: environmental determinants and propagule pressure Llewellyn C. Foxcroft, Mathieu Rouget, David M. Richardson and Sandra Mac Fadyen Diversity and Distributions, (2004) 10: 427–437

Effect of invasive species

Predation

Brown tree snake (Boiga irregularis)

• n Guam

Introduction

The brown tree snake was first detected on Guam in the 1950s near the Naval Port (central Guam), but may not have become conspicuous away from the port area until the early 1960s. By the mid 1960s, the snake had colonized over half of the island. In 1968, the snake had reached the extreme northern end of the island and was present throughout the island, although its densities varied widely from region to region.

Threat to other species

Status of forest species on Guam

Other threats Eradication and Detection http://www.fort.usgs.gov/Resources/Education/BTS/

Effect of invasive species

Predation Competition (native vs House geckos in the Pacific)

Effect of invasive species

Predation Competition Hybridization West slope cutthroat trout

Effect of invasive species

Predation Competition Hybridization Environmental engineering

Myrica faya on Hawaii

• Dr. Donald E. Gardner, University of Hawaii,

http://www.botany.hawaii.edu/faculty/gardner/biocontrol/myrica%20faya/myrica.htm

Effect of invasive species

Predation Competition Hybridization Environmental engineering

Myrica faya on Hawaii N-fixing root nodules

• Dr. Donald E. Gardner, University of Hawaii,

http://www.botany.hawaii.edu/faculty/gardner/biocontrol/myrica%20faya/myrica.htm

Habitat invaded by Myrica faya

• Dr. Donald E. Gardner, University of Hawaii,

http://www.botany.hawaii.edu/faculty/gardner/biocontrol/myrica%20faya/myrica.htm

Each year, ~ $23 billion nationwide is lost to the effects of invasive plants

• n agriculture, industry, recreation, and the environment. An estimated

1860 hectares (4600 acres) of land are invaded daily by invasive plants. (Federal Highway Administration 2000)

Effects of invasive species

Predation Competition Hybridization Environmental engineering Economic effects Invasive species is one of the major environmental issues of this century. The economic cost to the US of invasive species is at least $137B/year. (ESA 2000)

Factors affecting invasion

Basics Factors affecting invasion Introduction history

Factors affecting invasion: Introduction history

Pathways of introduction Ballast water Propagule pressure counteract small population challenges (e.g. genetic effects) Time since introduction Demographic processes Adaptation

Time since introduction

Opuntia invasion in South-Africa Correlation of area and introduction date

Factors affecting invasion

Basics Factors affecting invasion Introduction history Species characteristics

Factors affecting invasion: species characteristics

High dispersal rate Persistence at low density and fast growth

• e.g. asexual reproduction

Good ecological match large native range (can adapt to different habitats) generalists Associate with humans

Characteristics of invasive species

• Australian Weed Risk Assessment Model:

Predict what introduced species are likely to become invasive based on species traits.

An example of a predictive trait from the dayflower family

Jean Burns

Is self-compatibility associated with invasiveness?

Self-compatible Self-incompatible

Pollen grain

Murdannia nudiflora invasive Murdannia simplex noninvasive

Pagel94: D = 3.60, P = 0.01

Self-compatibility is associated with invasiveness.

Self-compatible Self-incompatible Invasive Noninvasive

Pagel94: D = 3.60, P = 0.01

Self-compatibility is associated with invasiveness.

Self-compatible Self-incompatible Invasive Noninvasive

Factors affecting invasion: community characteristics

Basics Predicting invasions Introduction history Species characteristics Characteristics of invasible ecosystems

Characteristics of invasible ecosystems

Disturbed/Early in succession good “Ecological Match”

Characteristics of invasible ecosystems

Disturbed/Early in succession good “Ecological Match” Predators few or absent (=enemy release hypothesis)

Invasible ecosystems: Enemy Release Hypothesis

Native Range Introduced Range

herbivory plant abundance herbivory plant abundance

Characteristics of invasible ecosystems

Disturbed/Early in succession good “Ecological Match” Predators few or absent (=enemy release hypothesis) Low diversity?

Invasible ecosystems: low diversity?

Islands are more invasible than mainlands (Elton 1958) Low diversity local communities are less invasible (Levine 2000) High diversity habitats are more invaded at large scales (Stohlgren et al. 2003)

Observations from islands, small-scale experiments, and mathematical models have generally supported the paradigm that habitats of low plant diversity are more vulnerable to plant invasions than areas of high plant diversity. We summarize two independent data sets to show exactly the

• pposite pattern at multiple spatial scales. More significant, and alarming, is that hotspots of

native plant diversity have been far more heavily invaded than areas of low plant diversity in most parts of the United States when considered at larger spatial scales. Our findings suggest that we cannot expect such hotspots to repel invasions, and that the threat of invasion is significant and predictably greatest in these areas.

Invasible ecosystems: low diversity? Invasive species

Basics Predicting invasions Introduction history Characteristics of invasive species Characteristics of invasible ecosystems Managing Invasives

What to do about invasives?

Prevent entry reduce human impact

Invasives: reduce human impact

What to do about invasives?

Prevent entry reduce human impact public education border control (Australian Weed Risk Assessment) Removal of invasives by hand vs pesticides biological control

What to do about invasives? Biological Control

Host Specificity Agent effectiveness

Biological Control: host specificity

(Soberón 2002)

Biological Control: host specificity

(Soberón 2002)

Biological Control: host specificity

Opuntia spinosissima Opuntia triacantha

Rare in native habitat lower chance of resistance in host Environment matching Using demographic models of evaluate effectiveness (remember PVAs?)

Biological Control: agent effectiveness

Biological Control: agent effectiveness

• Scotch broom

Ingrid Parker 2000, PVA

99.9% of seeds in prairies and 70% of seeds in urban populations need to be destroyed to stop invasion

• f scotch broom

Biological Control: agent effectiveness

Invasion front (fastest growing population) Established population (slowest growing population

PVA: Elasticity analysis of how to stop Scotch broom

Characteristics of invasible ecosystems

Disturbed/Early in succession good “Ecological Match” Predators few or absent (=enemy release hypothesis) Low or High diversity? Fragmentation