B. Statzner et al., REPRODUCTIVE TRAITS, HABITAT USE AND TEMPLET THEORY - A SYNTHESIS OF WORLD-WIDE DATA ON AQUATIC INSECTS, Freshwater Biology, 38(1), 1997, pp. 109-135
1. Using world-wide data on the reproductive biology of 131 species (i
n eight orders) of aquatic insects, we used multivariate analyses to e
xamine: (i) relationships among reproductive traits determining life c
ycle, fecundity, morphology, behaviour and physiology; (ii) relationsh
ips among traits determining spatial and temporal habitat characterist
ics at different scales; and (iii) the relationship between reproducti
ve and habitat-use traits. This provided a test of predictions of the
habitat templet concept on trends of species traits along gradients of
habitat heterogeneity. 2. The major trends observed in the relationsh
ips among reproductive traits were that larger females had larger eggs
, which were more vulnerable to perturbations such as droughts and oft
en laid in cocoons. In addition, they laid the eggs in larger numbers
of smaller clutches than smaller females. Other traits (e.g. egg numbe
r or incubation time) did not show clear trends. 3. Females that depos
ited eggs at sites of low local temporal heterogeneity (within plants)
used, at the same time, gross habitats of high temporal heterogeneity
(temporary waters). In contrast, traits in habitat use hardly differe
d on well-known gradients of temporal heterogeneity along running wate
rs (from source to estuary). The number of habitat units used by ovipo
siting females generally increased with the spatial scale considered,
most species oviposited in a single small habitat unit but in several
gross habitats. 4. A significant (P < 0.01) relationship between trait
s in reproduction and habitat use demonstrated that habitat acted as a
templet for reproductive strategies. This relationship was dominated
by larger females having larger, unattached eggs which were more vulne
rable to droughts and were oviposited in temporally more stable small-
scale habitats (within wood or macrophytes, or within cocoons spun by
the female) but more unstable large-scale habitats (primarily temporar
y waters). Thus, only on the small habitat scale did some of our obser
vations correspond to the predictions of the habitat templet concept (
e.g. larger size or higher vulnerability in more stable habitats). How
ever, many species had traits in reproduction that did not show trends
as predicted by the concept. 5. This and other recent studies of the
relationships between traits of freshwater organisms and the heterogen
eity of their habitats have shown that habitat acts as a templet for s
pecies life history traits. However, many of the details observed in t
hese studies did not correspond to predictions of the templet concept
because of trade-offs among the traits and scale problems in the descr
iption of habitat heterogeneity. Therefore, future studies should focu
s on groups of organisms which are as similar as possible in the trade
-offs among their species traits and on the potential relationships of
habitat heterogeneity across multiple scales.