Rundell Lab at SUNY-ESF
  • Home
  • People
    • Rebecca Rundell
    • Lab Members
    • Field Team Hall of Fame
    • Join Us
  • Publications
  • Research
  • Teaching
    • Palau Field Course
    • Palau field course blog
    • On Campus Courses
  • Outreach
  • Conservation
    • Belau
    • Elsewhere in Micronesia, including FSM
    • New York State
  • Field Sites
    • Belau
    • Elsewhere in Micronesia, including FSM
    • New York State
  • Animals
    • Pacific Island Land Snails
    • New York State Land Snails
    • Aquatic Invertebrates
  • Links

Invasional meltdown: Invader-invader mutualism facilitates a secondary invasion (summary by Anne)

4/9/2018

1 Comment

 
Citation:
Green, Peter T., Dennis J. O’Dowd, Kirsti L. Abbott, Mick Jeffery, Kent Retallick, and Ralph Mac Nally. Invasional meltdown: Invader-invader mutualism facilitates a secondary invasion. Ecology, vol. 92, no. 9, 2011, pp. 1758-1768.

Purpose:

Green et al. discuss the increasing prevalence of species invasion in all ecosystems due to human invasion and note the unexplored idea that interactions between invasive species in the same environment could have notable consequences, such as impacting invasion success and propagule pressure. The focus is brought to the invader-invader mutualism between the yellow crazy ant and honeydew-secreting scale insects, two bioinvaders of Christmas Island that together create yellow crazy ant supercolonies. Their interactions facilitate a secondary invader, the giant African land snail, by suppressing the native red land crab. The authors observe the relationship between the mutualistic invaders and the giant African land snail over the course of 7 years to gain insight on the poorly-understood effects of interactions between invasive species.

Methods:

The authors used Bayesian hierarchical models to determine if the effect of the ant-scale insect invasion influences the spread of giant African land snails, which they tracked over the course of 7 years. Potential reversal effects of suppressing the ant-scale insect supercolonies were explored, as well as the effect of suppressing the red land crab on giant African land snail populations through site comparisons and experiments.

Results:

The probability of giant African land snails invading sites with abundant red land crabs is 14 times lower than that for sites with no crabs or supercolonies, and 253 times lower than that for sites with supercolonies and a suppressed crab population. Managing these supercolonies at certain sites reverses the probability of snail invasion and recovers the crab population for those sites. At sites with supercolonies, almost all snail mortality is due to starvation, and ants only feed on dead snails.

Significance for Palau:

Palau is an isolated archipelago with a plethora of unique endemic species inhabiting its many islands; as a similarly isolated land mass, Christmas Island has evolved into a unique environment, housing many endemic species of its own. This study demonstrates how just two small exotic organisms, introduced to the environment through human interference, can become a massive threat to biodiversity in a given area. Furthermore, it demonstrates the importance of studying the interactions between invaders, as well as the success of suppressing the invasive populations to recover native populations. As a republic with an economy heavily based on tourism, Palau continues to be subjected to more and more invasive species that disrupt the delicate native ecosystems. This study is especially relevant to conservation in such a place, as it lays some of the groundwork required for remediating the natural environments of isolated land masses such as Palau.
1 Comment
Audrey Sellepack
4/15/2018 09:06:47 am

I found this post particularly interesting - especially since invasive species are one of the most common causes of biodiversity loss on our planet. Since Palau is an isolated island archipelago, many species haven't evolved in the presence of certain predators that humans may have introduced. Invasive species commonly travel to other areas via ships, and especially in the context of invasive invertebrates, they’re very difficult to eradicate at the source due to incredibly small larvae. Lots of conservation biologists are viewing invasive species as a problem that can only be managed, rather than totally eradicated, because it is nearly impossible to remove an invasive species entirely. However, reduced numbers of invaders can still have positive effects on an ecosystem.

In Palau, animals like rats could be serious invasive predators to land snails, or even the eggs of the precious Micronesian Megapode, Megapodius laperouse. Many of the species that rats prey on in Palau are on the IUCN red list and are targets for conservation. Therefore, many rat eradication programs have been put in place to potentially restore the species distribution to pre-rat levels. In Dr. Rundell's lab, there are several snail samples collected that give an overview of how the populations looked in certain habitats before a rat eradication program was put in place. It would be interesting to see when we go back there if that species composition has changed and if there is a greater distribution of more threatened species.

Reply



Leave a Reply.

    Rebecca Rundell & Jesse Czekanski-Moir

    Co-instructors, 2018

    Archives

    June 2019
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018

    Categories

    All

    RSS Feed

Powered by Create your own unique website with customizable templates.