DOI: 10.5061/dryad.jwstqjq9n
title: Primary data used to calculate predator-induced morphological changes in two Daphnia species-associated clones

description: The expression of inducible defences in reaction to an inconsistent
 predation pressure is especially well investigated in the freshwater
 keystone filter-feeder Daphnia. Out of their many inducible defences,
 which increase their fitness, the highest diversity of induced traits is
 found within their morphology. In recent time the focus of studies on
 these has switched, from the previously thoroughly covered large-scale
 defences, e.g., elongated/enlarged tail-spines, helmets and crests, to
 rather small-scale predator-induced changes. Inconspicuous spinules that
 cover the dorsal and ventral carapace margins have only rarely been
 featured in studies. We, therefore, tested two well-studied Daphnia
 species (D. magna and D. longicephala) for predator-induced changes
 concerning the spinules, i.e., their area of distribution relative to the
 body length (relative dorsal/ventral spinules-bearing area, relSBA) and
 their change in length (mean spinule length of the five central spinules
 along the dorsal/ventral carapace margin, mean SL). As invertebrate and
 vertebrate predators display differently built catching structures, those
 of invertebrate predators being more delicate, the defensive structures
 against these predator groups might vary accordingly. To test this, we
 exposed the daphnids to the vertebrate Leucaspius delineatus and a well
 co-studied predator of the respective Daphnia species, i.e., Triops
 cancriformis or Notontecta maculata. Our study discovered induced changes
 of the spinules’ lengths and an area they cover. These changes of
 inconspicuous traits appear not only to be predator-dependent, but also
 Daphnia-specific. The inconspicuous morphological changes of Daphnia, in
 combination with the large scale defences, here measured pointers for the
 expression of inducible defences were the tail spines (relative tail spine
 length, relTSL) in both species and the crest in D. longicephala, and some
 ultrastructural defences are suspected to be rather specifically
 customised collective defences.
description: Predator-exposure experiment, conducted with two
 <i>Daphnia</i> species: <i>D. magna</i> and
 <i>D. longicephala</i> (one clone each)
 Three exposure treatments: control, <i>Leucaspius
 delineatus</i>-exposure, <i>Triops cancriformis</i>-/
 <i>Notonecta maculata</i>-exposure
 Laboratory experiment For full explanation see
 manuscript
description: The files contain the primary data of the mentioned species’
 clones within the respective titles. 
 Measured/calculated traits: <em>D.
 magna</em>: 
 Body length [µm] Tail-spine length
 [µm] Relative tail-spine length [%]
 Spinules bearing area dorsal [µm] Relative
 spinules bearing area dorsal [%] Spinules bearing
 area ventral [µm] Relative spinules bearing area
 ventral [%] Spinule length dorsal (1-5)
 [µm] Mean spinule length dorsal [µm]
 Spinule length ventral (1-5) [µm] Mean
 spinule length ventral [µm] 
 <em>D. lngicephala</em>: Body length
 [µm] Tail-spine length [µm]
 Relative tail-spine length [%] Crest width
 [µm] Spinules bearing area dorsal [µm]
 Relative spinules bearing area dorsal [%]
 Spinules bearing area ventral [µm] Relative
 spinules bearing area ventral [%] Spinule length
 dorsal (1-5) [µm] Mean spinule length dorsal
 [µm] Spinule length ventral (1-5) [µm]
 Mean spinule length ventral [µm] 
 Other
 traits included in the files: Rearing method:
 Alone (one
 animal in 160 ml glass) Multiple (maximum of 14 animals
 in 2 L glass beakers)