invasive species

whts it called once a non-native species has become established

naturalized

if you plant a shrub from Australia in your backyard, what is it considered

introduced

not naturalized

If you go to San Francisco and you see those

parrots flying around and they're breeding

naturalized

when does a species become invasive

When that species is actively disrupting the natural ecosystem

and causing some big impacts

Invasion pathways - water

big cargo ships that take in water and

put it in the bottom of the ship it's called ballast water

to stabilize them and they'll do that at when they're

first kind of being loaded up and then And they go across

the sea and they release that water in a new place,

Invasion pathways - food

Crops, livestock, honeybees, etc.

Invasion pathways -Horticulture and the pet trade

Escapes, intentional releases, etc.

Invasion pathways -Biological control

taking

a species from one place and bringing it to another

place to control a species, a pest.

The 10s rule

imagine all of the species

that are imported that make it to a given place.

About one in 10 actually escape,

Then of those, about one in 10 become naturalized, remember,

create that self-sustaining population. And then of those

that naturalize, about 1 in 10 actually become invasive,

rare that a species transitions from

– Imported escaped naturalized invasive

Common traits of invasive species…

1. Rapid population growth

2. High dispersal rate

3. Large range size (tolerates many climates)

4. Prior history of invasions elsewhere

Enemy release hypothesis

species become

invasive when they escape their natural enemies

Biotic acceptance

diverse communities with

similar species are easy to invade because

conditions are likely good for the invader.

• if there are

  similar species to you there, then the conditions for you are

  probably decent, and then you'll be able to thrive

Biotic resistance

diverse communities are hard

to invade due to more predator/competitor species

Impacts on native species - Hybridization

we take an invasive species

we move it to a new place and it starts

interbreeding with the native species and then like sort of

like genetically contaminating the species in some way

What do you think is the most cost effective way

to deal with invasive species?

(a) Prevent them from arriving in the first place

(b) Monitor and then eradicated early

(c) Eradicate established populations

(d) Maintain small populations

(e) Nothing will work!

(a) Prevent them from arriving in the first place

Lacey Act

was first in US to protect wildlife

by regulating import/export of wildlife and plants

monitor

There's only a fraction of the species, about 10%.

And there's a time lag before species transition

from becoming invasive after they've been naturalized = early eradication

places in the world

where eradication tends to be most successful are

usually

bounded places, like islands,

• reinvading a place is a lot harder

Novel ecosystems

that

ecosystems now are just different than the past and they're

so different that re-establishing a historic baseline is

infeasible and they might provide us with benefits already.

Maybe it's too costly. Maybe these new ecosystems are still

speciose. They're still biodiverse, maybe even more than

the native ones.