Invasive species

Question 1

Stephens Island Wren

Galbreath & Brown 2004 Notornis

Answer 1

Stephens Island, New Zealand
1984, 10 specimens brought in by lighthouse cat
Cats established thereafter (10’s)
Cats drove wren extinct

Question 2

Angel de la Guarda Deer Mouse

Vázquez-Domínguez et al. 2004 Oryx

Answer 2

Isla Estanque, Mexico
Abundant 1995
1 x domestic cat 1998
~100 scats collected
90% contained deer mouse hair
No deer mice 98, 99, 01
CR elsewhere

Question 3

Steadman 1995 Science

Answer 3

The loss of birdlife in the tropical Pacific may exceed 2000 species (the majority of which were species of flightless rails)

Question 4

Duncan et al. 2013 PNAS

983 species extinct in the pacific

Answer 4

We calculate that human colonization of remote Pacific islands caused the global extinction of close to 1,000 species of nonpasserine landbird alone; nonpasserine seabird and passerine extinctions will add to this total.

Question 5

Pacific Island extinctions

Answer 5

Mostly wholly or partly due to introduced predators
Cats, rats, pigs, snakes
Avian malaria
+Hunting by man
+Habitat conversion
What do extinctions mean for ecosystem functioning?

Question 6

Functional consequences on Guam

Caves et al.,

Answer 6

Brown tree snake
Introduced late 1940’s
Near-complete loss native forest birds by late 1980’s

Question 7

Functional consequences on Hawaii - Avian malaria

Answer 7

52 endemic species at European contact
Third gone extinct, many others critical

Cox & Elmqvist 2000
Conserv Biol

Question 8

Extinction of Hawaiian Lobelia

Answer 8

Cascading extinction of 31 species Hawaiian Lobelia in last century
As a result, 31 species of the Cam- panulaceae have gone extinct in the last century (K. Wood, personal com- munication). Reduction in the popu- lation sizes of native Campanulaceae and loss of the plants as a nectar source has in turn affected relic pol- linator populations, causing evolu- tionary changes in beak morphology (Smith et al. 1995; Buchman & Nab- han 1996).

Question 9

Introduced species

Answer 9

An introduced species is one that:
Lives outside of its native range
Arrived by human activity
Deliberate – garden plants
Accidental – ballast in ships
How big is the problem?

Question 10

Global exchange and accumulation of non-native plants

Answer 10

13,168 plant species

Question 11

Invasive species

“From Russian beetles to giant African snails, the U.S. is under assault—and it’s costing us billions”

Answer 11

Are introduced species that spread to:
Damage environment
Economy
Human health
Plants, animals or diseases

Question 12

Assembled all costs in USA, UK, Australia, South Africa, India & Brazil

Answer 12

Crop, forestry & livestock pests, + human disease

US$ 314 billion / year

Question 13

Implications for conservation

Answer 13

Dramatic extinction from introduced predators on islands
Major issues on continents:
Chytridmycosis
Cane toads
Nile perch

Question 14

Chytrid is dispersed by frog trade?

Schloegel et al., 2012
Hybrid genotypes of amphibian chytridiomycosis associated with the bullfrog trade

Answer 14

South African clawed frog
Global pet & zoo trade
Biomedical sciences

Tested 145 specimens at California Academy of Sciences
4% infected with chytrid

Question 15

Scale of problem?

Smith et al. 2009 Science

Answer 15

Live animals imported to USA between 2000-06 = 1.5 billion

Global estimates >1 billion / year

Question 16

Invasive cane toads cause mass mortality of freshwater crocodiles in tropical australia

Answer 16

Letnic et al., 2008

Question 17

Nile Perch in Lake Victoria

Answer 17

Introduced late 50s
Explosive increase 80s
Fish yield increased      3- to 4-fold
Fisheries biologists consider this a success
What about conservation biologists?

Question 18

> 300 species endemic cichlid

Destruction of endemic species flock: decline of cichlids of lake victoria

Answer 18

Extrapolations suggest ~200 species disappeared or threatened with extinction

Question 19

Implications for conservation

Answer 19

Dramatic consequences of introduced predators on islands
Also major issues on continents:
Chytridmycosis
Cane toads
Nile perch
Key question:
How to manage invasive species to prevent conservation losses?

Question 20

Managing invasiveness

Answer 20

Area and growth, carrying capacity and control costs

Question 21

(1) Prevention is better than cure

Answer 21

(2) Predict invasive species

Question 22

Remotness promotes biological invasions on islands worldwide

Moser et al., 2018

Answer 22

. While isolation has shaped natural colonization of islands for millions of years, globalization in trade and transport has led to a breakdown of biogeographical barriers and subsequent colonization of islands by alien species. Using a large dataset of 257 subtropical and tropical islands, we show that alien richness increases with increasing isolation of islands. This pattern is consistent for plants, ants, mammals, and reptiles, and it cannot simply be explained by island economics and trade alone. Geographical isolation does not protect islands from alien species, and island species richness may reach a new dynamic equilibrium at some point, likely at the expense of many endemic species.

Question 23

Models using biological attributes could not predict invasiveness of species pairs
European range predicted invasiveness of 70% of species pairs
Big range =
wide environmental tolerances

Answer 23

165 species pairs
1 invasive in New Brunswick, Canada
1 congeric species not invaded
Three biological characters
Lifeform, stem height, flowering period
European geographic range

Question 24

Predicting the Australian weed status of southern african plants

Answer 24

Best predictors were:
Weed status in s. Africa
Climatic range in s. Africa
congeric weeds in s. Africa
But only good predictors when present >140 yrs
No clear synthesis for targeted quarantine or eradication of newly introduced species

Question 25

Plants at highest risk of becoming invasive:
Aquatic or semi-aquatic
grasses, nitrogen-fixers
climbers, clonal trees

Answer 25

Only 25% invaders are serious agri-weeds

No clear synthesis for targeted quarantine or eradication of newly introduced species

Question 26

(3) Eradication of invasives

Answer 26

Goats on Galapagos
‘Judas’ goats
Carrion et al.
11 million dollars

Question 27

Rodents on Oceanic Islands

Answer 27

“Galapagos to poison 180 million invasive black rats”

Nov 15, 2012

Question 28

House mouse, Gough Island, eating Tristan Albatross (CR) chick

Answer 28

Those birds do not evolve to have defence
Rodenticides used in 284 island eradications
Eradications from 284 islands (47,628 ha)
35 others failed (mostly mice)
Cost per hectare 3-2000 dollars

Question 29

(4) Local control of invasives

Answer 29

Scotch Broom removal
Milo McIver State Park, USA
Limited resources or infestation preclude eradication
Control by reducing density
Manual (digging, pulling)
Mechanical (cutting, girdling)
Prescribed fire
Chemical control (pesticides, herbicides)
Biological control (grazers, introductions??)
Allows other species to survive (thrive?)

Question 30

Are many non-natives so bad?

Answer 30

Gnangara Pine Plantation, WA
Why are pines a problem?
Aquifers supply Perth
38% water loss to pines
Solution?
Clear the plantations
Carnaby’s Black Cockatoo
Use pines for    6-month non-breeding season
Seeds 27% more nutritious than native seeds
What should be done???

Question 31

Java sparrow
Highly threatened by cagebird trade
64 locations studied  109 individuals at 17 sites

Answer 31

Introduced populations:
Hawaii
Philippines
China (100-10,000 breeding pairs, BPs)
Taiwan (<100 BPs)
Japan (<10,000 BPs)
Survival of Java sparrow in the ‘wild’ most likely in novel locations

Question 32

Novel ecosystems

Definition: Development of ecosystems that differ in composition and/or function from ‘native’ systems
Inevitable consequence of rapid human-induced changes to species distributions and environments

Answer 32

Complex management & ethical dilemmas
Novel ecosystems damage native fauna
Vs. benefits to threatened species
Recovery of ecosystem goods & services
Whether & how to act is emerging field

Question 33

Summary

Answer 33

Invasives driven 1,000’s extinctions
Prevalent globally
Cause billions in economic costs
Difficult to predict invasives
Hard / expensive to eradicate them
Local control often only option
Mankind rapidly creating novel ecosystems
 Complex conservation dilemmas