Classics: Invasion Meltdown

26 10 2008

One for the Classics page…

melting_rat_by_xenatalhaoui-d71xr1yDaniel Simberloff is probably best known for his work on the implications of invasive (non-indigenous) species for biodiversity, although he has contributed to a wide range of conservation disciplines.

A seminal paper that he co-wrote with Betsy Von Holle is one I consider to be a conservation Classic: their 1999 paper in the inaugural issue of Biological Invasions entitled Positive interactions of nonindigenous species: Invasional meltdown?

The establishment of non-indigenous species can have severe negative impacts on ecosystems. Introduced species that become invasive (widespread and locally dominant) transform habitats, degrade ecosystem services, reduce biodiversity and are some of the greatest threats to ecosystems today (perhaps nearly as important as habitat loss and over-exploitation).

The so-called ‘invasion meltdown‘ describes the process by which the negative impacts induced on native ecosystems by one invading non-indigenous species are exacerbated by interactions with another exotic species.

Although there isn’t a lot of information on invasion meltdowns, one good example comes from Christmas Island in tropical Australia. The introduced yellow crazy ant (Anoplolepis gracilipes) exploded in numbers when another exotic species, a scale insect, was introduced about the same time that a native scale insect species also had a local outbreak.  Because ants protect scale insects from predators and parasites in return for scale honeydew, the crazy ant suddenly had a much more abundant food source, leading to the huge increase in the ant population. This large ant population devastated the population of native red crab (Gecarcoidea natalis) and resulted in massive increase in forest undergrowth due to reduced herbivory by crabs (see O’Dowd et al. 2003). The great decline in red crabs may also make the island more vulnerable to other plant invasions.

What did Simberloff & Van Holle’s idea and subsequent examples of invasion meltdowns teach us? I believe their paper really hit home the idea that invasive species were not only a threat to biodiversity, but the self-reinforcing mutualisms of invasive species could rival other forms of human-induced biodiversity decline. Indeed, many of the effects of invasive species will be reinforced by global climate change through increasing temperatures, rising sea levels and changing rainfall patterns that increase the potential range and spread of invading species, so the problem is only going to get worse. This is why the U.N. began the Global Invasive Species Programme (GISP), and world-wide, countries are attempting to restrict the flow of invasive species so that their negative effects are lessened. Identifying the extent of the problem has stimulated a lot of people to act accordingly.

CJA Bradshaw

Add to FacebookAdd to NewsvineAdd to DiggAdd to Del.icio.usAdd to StumbleuponAdd to RedditAdd to BlinklistAdd to Ma.gnoliaAdd to TechnoratiAdd to Furl


Actions

Information

6 responses

13 03 2017
A minuscule wasp could save Christmas Island’s stunning cherry-red crabs from crazy ants | Florida Bed Bugs Experts

[…] The interaction between these two invasive species has allowed them to build their populations to extremely high concentrations, something known as invasional meltdown. […]

Like

2 12 2016
A tiny wasp could save Christmas Island’s spectacular red crabs from crazy ants – Enjeux énergies et environnement

[…] The interaction between these two invasive species has allowed them to build their populations to extremely high densities, something known as invasional meltdown. […]

Like

26 06 2015
Just give them a lift | ConservationBytes.com

[…] habitat, etc.), but as we’ve seen the world over in the case of successful alien species, invasions can be remarkably successful (at least from the perspective of the invading […]

Like

14 03 2014
Lower biodiversity => lower human health | Green Resistance (teaching, organizing, and eco-thinking)

[…] do need the reminder, though.  We do need to be told again that habitat loss, fragmentation, invasive species, over-exploitation and of course,climate change, are bad for biodiversity.  And that a degraded […]

Like

27 10 2008
Corey Bradshaw

For more information on invasive species in Australia, visit http://www.feral.typepad.com/

CJA Bradshaw

Like

26 10 2008
australian food act | Bookmarks URL

[…] Classics: Invasion Meltdown Although there isn’ta lot of information on invasion meltdowns, one good example comes from Christmas Island in tropical Australia. The introduced yellow crazy ant (Anoplolepis gracilipes) exploded in numbers when another exotic species … […]

Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s