ecology of phasmids - KLUEDO - Universität Kaiserslautern
ecology of phasmids - KLUEDO - Universität Kaiserslautern
ecology of phasmids - KLUEDO - Universität Kaiserslautern
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Introduction 4<br />
Description <strong>of</strong> phasmid<br />
community parameters<br />
(in the field from linetransects)<br />
Diversity<br />
Top-down control<br />
Predation-mediated mortality <strong>of</strong><br />
nymphs (field experiment)<br />
Biotic<br />
Distribution Focus on population<br />
Estimates<br />
potential<br />
Abundance parameters <strong>of</strong><br />
from lab<br />
Potential food<br />
Realized niche Metriophasma diocles<br />
population<br />
niche<br />
Bottom-up control<br />
leaf traits <strong>of</strong> host-plants and their<br />
effects on performance <strong>of</strong> nymphs<br />
and preference <strong>of</strong> adults (feeding trials<br />
in the lab)<br />
Figure 1-1: Study design: The outer circles represent the main focuses <strong>of</strong> Chapters 2 to 5.<br />
As a first step, Chapter 2 addresses the structural aspects <strong>of</strong> the phasmid community on BCI.<br />
Distribution and abundance <strong>of</strong> herbivores may be modulated by resource limitation (e.g., Joern &<br />
Gaines 1990), and knowledge about the food niche <strong>of</strong> herbivores is crucial for an evaluation <strong>of</strong> resource<br />
restrictions. If <strong>phasmids</strong> behave as specialists, their habitat should generally reflect the habitat <strong>of</strong> their<br />
host plants. In contrast, generalists should be less dependent on host plant distribution. Thus uncovering<br />
the diet breadth <strong>of</strong> herbivores directly relates to understanding habitat choice. In combining information<br />
on (1) plant species <strong>phasmids</strong> were observed on along line-transects with (2) feeding-trials in the lab the<br />
realized food niche can be separated from other niche dimensions that are typically incorporated in field<br />
studies. The difference between realized and absolute food niche then allows to conclude on other<br />
impact factors like climate or natural enemies. The estimation <strong>of</strong> phasmid densities provides a basis for<br />
the following chapters.<br />
The realized population densities reflect an organism in the boundaries <strong>of</strong> its environment (Begon et al.<br />
1996). In Chapter 3, I meet the question what is the inherent potential <strong>of</strong> the phasmid species<br />
Metriophasma diocles to reproduce free from environmental limitations. I modeled the potential<br />
population growth <strong>of</strong> M. diocles on the basis <strong>of</strong> life cycle parameters like sex ratio, female fecundity and<br />
generation time assessed from a laboratory population. The difference between potential and realized