The Impact of Carnivorous Species Extinction on Indirectly Interacting Species

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(Photo by wildaboutants, http://blog.wildaboutants.com/2010/05/04/oleander-aphids-on-milkweed/)

The latest research on the effect that species have on each other has led to unprecedented conclusions that present challenging new directions for future conservation effort.  Previous knowledge of species’ population fluctuation and extinction did not indicate the intricacies and extensive consequences of the interconnectedness of the food web. While it may seem important to focus on endangered species, the real solution may be a more comprehensive view. This study published in Ecology Letters reveals evidence for the dire need of general intervention and protection of entire ecosystems in order to protect a greater number of species.

The extinction of a particular species has been revealed to be likely to cause extinction in similar species that fulfill homologous roles in an ecosystem. Seemingly unrelated species are likewise affected, whether or not there is an obvious correlation because of the many invisible bonds between species and their indirect interactions.

When the population of a species fluctuates, extinction in other species can occur as well. This is largely surprising because intuitively, if the numbers of a competing organism were declining, it would seem that the original species would have greater access to prey and more freedom in their niche. However, population fluctuations in one species do affect both species similar and different from them. The consequences of even population number change then, needs to be seriously considered.

Research has revealed that the indirect effects within an ecosystem upon a species are as deleterious as direct harm to a species itself. Rather than approaching the problem one species at a time, there is a necessity for realization that multiple species are in danger concurrently. Attempts to salvage damage done to one species, or restore particular endangered species may be somewhat futile. Even if one species is saved, there are many species slowly declining or becoming extinct at the same time that slipped under the radar.

Ample evidence was provided to indicate the serious effects of these indirect interactions through the investigation by researchers of a set of four “ecosystems” with three species of wasps, and three species of aphids in each one. Over the course of 14 weeks, the scientists removed one species of wasps from three of the ecosystems, and left the other one as a control. The aphids, which were the prey, flourished in the decline of predators, but the remaining wasp species declined with the removal of one of the wasp species.

These smaller ecosystems provided strong evidence for the claim that species decline and extinction can cause extinction is other species. It also revealed that there is much that yet needs to be discovered about the complexity of the food chain and ecosystem dynamics. Seemingly unrelated species can be directly affected through indirect interactions within the ecosystem. There is dire need for a new approach to conservation that approaches the problem appropriately.  

 

Reference:

Sanders, D., Sutter, L., Frank van Veen, F. J. (2013). The loss of indirect interactions leads to cascading extinctions of carnivores. Ecology Letters (2013) 16: 664–669. Retrieved from http://onlinelibrary.wiley.com/doi/10.1111/ele.12096/full

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