ecology of phasmids - KLUEDO - Universität Kaiserslautern
ecology of phasmids - KLUEDO - Universität Kaiserslautern
ecology of phasmids - KLUEDO - Universität Kaiserslautern
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Community structure & host range 19<br />
Absolute abundance [ind.]<br />
40<br />
35<br />
30<br />
25<br />
20<br />
15<br />
10<br />
5<br />
0<br />
Nymphs Adults<br />
May-00<br />
Jun-00<br />
Jul-00<br />
Aug-00<br />
Sep-00<br />
Oct-00<br />
Nov-00<br />
Dec-00<br />
Jan-01<br />
Feb-01<br />
Mar-01<br />
Apr-01<br />
May-01<br />
Jun-01<br />
Jul-01<br />
Figure 2-3: Temporal fluctuations <strong>of</strong> absolute phasmid abundances along forest edges on BCI for phasmid<br />
nymphs (black bars) and phasmid adults (white bars). Each bar represents the cumulative catch per month along<br />
three line-transects (N = 286). Please note that Oct. 2000 and Jul. 201 were excluded from GOF tests.<br />
2.3.3 Food niche<br />
Single phasmid species showed a highly aggregated distribution on particular host plant families<br />
resulting in narrow resource niches with values for Levin’s standardized niche breadth BA ranging from<br />
0 (Otocrania sp.) to 0.40 (Bacteria ploiaria) (Table 2-2). For example, the low niche breadth <strong>of</strong> 0.10 for<br />
I. dentipes (the second most abundant species in forest edge habitats; cf. Figure 2-1) resulted from 68<br />
specimens recorded on two plant families, and 91 % <strong>of</strong> these specimens were found on two individuals<br />
<strong>of</strong> Vismia baccifera (Clusiaceae). All three individuals <strong>of</strong> Otocrania sp. were found on Sapindaceae.<br />
Niche breadth was larger in the other three species because they were recorded on more plant families<br />
and individuals were less aggregated (major proportion <strong>of</strong> individuals per plant family: O. martini, 55 %<br />
on Clusiaceae, 18 % on Euphorbiaceae; B. ploiaria, 34 % on Rhamnaceae; M. diocles, 49 % on<br />
Piperaceae,and one third <strong>of</strong> these on P. marginatum, 25 % on Araceae).<br />
Generally, resource niches <strong>of</strong> phasmid species were separated as demonstrated by Pianka’s index <strong>of</strong><br />
niche overlap Ojk, usually ranging from 0 to 0.19. In contrast, niche overlap between O. martini and<br />
I. dentipes was high (Ojk = 0.91) because 55 % <strong>of</strong> the O. martini and 91 % <strong>of</strong> the I. dentipes individuals<br />
shared 2 individuals <strong>of</strong> Vismia baccifera as food resource (cf. Table 2-2).