50 years of invasion ecology – the legacy of Charles Elton

The Environment Institute Where ideas grow Professor David Richardson 50 years of invasion ecology – the legacy of Charles Elton

50 years of invasion ecology – the legacy of Charles Elton David M. Richardson

Lygodium microphyllum (Old World climbing fern), Florida

Mimosa pigra, northern Australia

Acacia saligna Acacia cyclops South African fynbos Pinus pinaster Hakea sericea

Nile perch, Lates niloticus, Lake Victoria

(2000) BioScience

Global human population Global human population Source: Wikipedia

Kareiva et al. (2007) Science

International shipping has increased by a factor of 10 over the last few decades

Totally new vectors & pathways

Air transport Billion passenger km 3000 2500 2000 1500 1000 500 0 1950 1970 1990

Massive habitat transformations and alterations to prevailing disturbance regimes

Afforestation with alien trees (including agroforestry)

Increasing use of alien plants in horticulture… the never-ending search for novelties Nurseries - new arrivals originate from a wider source www.tubsandshrubs.co.uk http://www.plantnurseries.us area than early introductions & they tend to arrive via more direct routes and in bigger numbers than in the past http://www.mountainmeadowfarm.org Image: Jeff Greenberg

Pet trade!!

Residence time Propagule pressure

Factors implicated in global amphibian declines

WHAT IS INVASION ECOLOGY? • The study of the human-mediated introduction of organisms, especially introductions to areas outside the potential range of given organisms as defined by their natural dispersal mechanisms and biogeographical barriers. • Addresses all aspects relating to the introduction of organisms, their ability to establish, naturalize and invade in the target region & their interactions with resident organisms in their new location. • Considers costs and benefits of their presence and abundance with reference to human value systems.

INVASION ECOLOGY – KEY PHASES •Pre-Elton (<1950) •Elton (1950s – early 1980s) •Scope (mid 1980s – late 1990s) •Today (>2000) Ricciardi & MacIsaac (2008)

Charles Darwin (1809-1882) „… floras gain by naturalization, proportionally with the number of the native genera and species far more in new genera than in new species‟ (Darwin 1859). (Darwin 1839)

Pyšek et al. (2008) Diversity and Distributions Invasion rate of Heracleum mantegazzianum in the Czech Republic.

Billion passenger km 3000 2500 2000 1500 1000 500 0 1950 1970 1990

1926 1958 Charles Elton (1900-1992)

Whytham Woods, Oxfordshire, UK “Investigations of the role of competition, predation, and abiotic stress in shaping natural communities were a staple for previous generations of ecologists”. [Bruno et al. (2003) Trends in Ecology and Evolution].

“Biotic resistance”

Robert M. May (1936 - ) Robert H. MacArthur (1930 – 1972)

International Conference on Mediterranean-Type Ecosystems (MEDECOS) Stellenbosch, South Africa 1980

International Programme on the Ecology and Management of Biological Invasions Three main questions: 1) Which species invade? 2) Which habitats are most susceptible to invasion? 3) Do we know enough to manage #1 and #2?

Jim Brown Simon Levin Mick Crawley Paul Ehrlich Mark Williamson Dan Simberloff Hal Mooney Stuart Pimm

Mark Williamson 1996

The Norway/UN Conference on Alien Species Trondheim, Norway July 1996 GISP •Human dimensions •Ecology of introductions •International pathways •Management tools •Country case studies (1998) •Where to from here?

The Global Invasive Species Programme (Phase 1)

Naturalized/ Introduced invasive

Status of taxa GEOGRAPHIC ENVIRONMENTAL (LOCAL) casual REPRODUCTIVE alien DISPERSAL ENVIRONMENTAL (DISTURBED HABITATS) naturalized ENVIRONMENTAL (NATURAL HABITATS) invasive Richardson et al. (2000) Diversity and Distributions

Status of taxa GEOGRAPHIC ENVIRONMENTAL (LOCAL) Traits of the organism casual REPRODUCTIVE The naturalization – invasion process alien DISPERSAL ENVIRONMENTAL (DISTURBED HABITATS) naturalized “Invasiveness” ENVIRONMENTAL (NATURAL HABITATS) invasive

The naturalization – invasion process ENVIRONMENTAL (DISTURBED HABITATS) ENVIRONMENTAL (NATURAL HABITATS) Traits of the organism “Invasiveness” ENVIRONMENTAL (LOCAL) REPRODUCTIVE GEOGRAPHIC Features of the environment DISPERSAL “Invasibility” alien naturalized Status of taxa casual invasive

Beginning with Elton (1958), community susceptibility to invasion has largely been treated as a yes/no issue: communities are either deterministically resistant or susceptible to the invasion of a particular species (A). Realistically, however, communities vary continuously in their susceptibility to invasion, making invasion success a probabilistic process (B) D‟Antonio et al. (2001) Journal of Mediterranean Ecology

The naturalization – invasion process ENVIRONMENTAL (DISTURBED HABITATS) ENVIRONMENTAL (NATURAL HABITATS) ENVIRONMENTAL (LOCAL) Pollinators REPRODUCTIVE GEOGRAPHIC DISPERSAL Seed dispersers! Morella faya invading lava flows; Hawaii alien Mycorrhizal naturalized Status fungi of taxa Nitrogen-fixing bacteria casual invasive

Rejmánek et al. (2005) Marcel Rejmanek Pulling together the threads – towards a causal explanation for invasiveness

•Invading species must have access to available resources (light, nutrients, water, etc) Fluctuating resource •An invading species will be availability theory more successful at invading a of invasibility community if it does not encounter intense competition (Davis et al. 2000) for these resources from resident species. •Experiments and long-term monitoring studies - fluctuation in resource availability = the key factor controlling invasibility

Elton’s legacy?

Elton’s legacy? “To us, the overriding feature of Elton‟s book, and the primary reason for its landmark status in invasion ecology, is simply that it brought together previously disparate themes (biogeography, conservation biology, epidemiology, human history, population ecology, and others) to show the true global scale and the severe and escalating implications of biological invasions for life on earth. He placed the phenomenon in the context of ecological understanding of the time, and provided a map for new research directions.”

Elton’s legacy? “Elton and his monograph, in fact, had limited influence on the development of invasion biology – he was a prophet rather than a founder...” Dan Simberloff (in press)

BROW – Silky smooth EYES – Wide open MOST IMPORTANT – Big baby cheeks NOSE – Long and straight LIPS – Juicy but not too much JAW – Defined and angular SKIN – Plumped; nothing taut OVERALL – Heart-shape effect

SCIENCE Improved conceptual frameworks Naturalized/ Introduced invasive

SCIENCE Better global coverage Trends in Ecology & Evolution 23 237-244 (2008)

Conflict resolution Most pressing Eradication? management Early detection Restoration issues Prevention Containment, control & mitigation Monitoring Integrated land management MISMATCH! SCIENCE Tenuous links Besides a better between current understanding of the research output and “nuts & bolts”, a greater most pressing focus research on key management issues management issues Vectors Homoclime Autecology Population Impact assessment & analysis (biocontrol) dynamics “Invasion pathways Control & restoration ecology ecology” Bioclimatic modelling alien Landscape ecology Cost-benefit analysis naturalized Status of taxa casual invasive

Needed! New partnerships SCIENCE Better links with a wide range of other disciplines

Consideration of management options – firmly grounded in risk-analysis/risk-management

ENVIRONMENTAL (DISTURBED HABITATS) ENVIRONMENTAL (NATURAL HABITATS) COMPONENTS OF THE LAG PHASE DISPERSAL PATHWAYS ENVIRONMENTAL (LOCAL) REPRODUCTIVE GEOGRAPHIC DISPERSAL IMPACTS Pollinators DISPERSAL PATHWAYS alien naturalized Status of taxa casual invasive

Thanks for your attention!

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50 years of invasion ecology – the legacy of Charles Elton

by University of Adelaide on Sep 14, 2009

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