In my current work, I found a non-linear effect of invasive predators to a native mammal community. That is, the invasive predator had a slightly positive effect to species richness of native mammals when its activity was low, but the effect became negative and rose quadratically when its activity exceeded a threshold. I am trying to explain such findings. Is there any reference explaining this phenomenon? Thank you.
It could be that at low predator levels, competition is the main interaction. But when predator levels increase, predation takes over. So, maybe your observations reflect two different phenomena. This happens with seed dispersal in trees, where seeds are dispersed locally via one dispersal kernel and long distance by another. Sometimes you have to combine models to explain your phenomena. Also, you may need to construct a mechanistic model to account for the behaviour, which can incorporate mathematical explanations :)
See: Article Unexpected consequences of control: Competitive vs. predator...
Why do you expect a linear relationship? Theory, hypothesis? If 'activity' (density?) increases, prey specialisation becomes relevant?
It could be that at low predator levels, competition is the main interaction. But when predator levels increase, predation takes over. So, maybe your observations reflect two different phenomena. This happens with seed dispersal in trees, where seeds are dispersed locally via one dispersal kernel and long distance by another. Sometimes you have to combine models to explain your phenomena. Also, you may need to construct a mechanistic model to account for the behaviour, which can incorporate mathematical explanations :)
See: Article Unexpected consequences of control: Competitive vs. predator...
Check out the recent paper by Jason Fisher and Cole Burton - Wildlife Winners and losers in an oil sands landscape. The concept of "meso-carnivore release" may be at play in your study.
Did you do the transformation and/or normalization for your data? that would made it easier to analyze and understand.
Hello - you may consider looking into the 3 functional responses of predation (Type I, II, and III). If you have prey density data and number of prey consumed data, creating that graph may be telling. However, even with those data graphed, sometimes only part of a functional response is captured in the illustration. Also, are these predators more successful at consuming prey when predator numbers are higher because of hunting tactics (such as pack hunting)?
- Badges
- Science method
- Similar topics
- Biological Science
- Ecology