Never trust Australians; are Banksia and Acacia becoming a

problem in New Zealand?

Gary Houliston, Peter Heenan

Landcare Research, Lincoln, New Zealand

Lots of bad / unpleasant things come from Australia:

Plant Invasions in New Zealand• 29000 introduced plant species in New

Zealand

• 700 new emerging weeds reported in the last 20 years (approx 1 every 10 days)

• Border incursions are minor!

Genetics of plant invasions

• Plants usually undergo a “lag-phase” between introduction and invasion

• What causes plants to emerge from the “lag-phase”– Local adaptation– Propagule pressure

Two case studies:Acacia pravissima

Banksia integrifolia

“Coastal Banksia”

• Popular nursery plant!

• Australian Dryland / coastal species

• Sampling across Australian / New Zealand Ranges

Banksia integrifolia in NZ

• Planted to stabilise sand dunes / ornamental

• Naturalising in several regions

• Fast growing, high seed output

• Widespread coastal species in native range

Microsatellites developed for Banksia oblongifolia

• Five reliable markers

• 2- 8 alleles per locus

• Initial analysis for 98 individuals (27 from NZ, 71 from Aust)

QLD N = 17

NSW, VIC N = 54

NZ N = 27

Principle Co-ordinate Analysis

• Pco

Principal Coordinates

1

1

1

1

2

3

2

2

1

1

11

1

11

11

2

2

2

2

2

2

1

1

1

33

3

33

33

12

1111

11311111122222113

11111111

32222

111

33322

1111 11

2233312

221111

12

Coord. 1

Co

ord

. 2

1 = NSW / Vict, 2 = NZ, 3 = QLD

Why does it matter?

• Variable populations are generally:

–Healthier / more vigorous

–Better able to resist control agents

–More likely to match the local environment

–Have full suite of reproductive types

Acknowledgements

• Landcare Research FRST Capability Fund

• Linda Broadhurst / Andrew Young CSIRO

• Melbourne University Herbarium