Figure 1.
Inducible morphological defenses against Chaoborus predation in the second juvenile instar.
A: Chaoborus kairomone significantly increases neckteeth expression in juvenile D. pulex. B and C: No significant impact was observed on life history parameters at sexual maturity of Chaoborus exposed D. pulex. Body length (B) and number of neonates (C) is not significantly different from control groups. Plotted are medians and interquartile ranges. Bonferroni corrected significance levels: *p<0.025; **p<0.005; ***p<0.0005.
Figure 2.
Life history shifts against Gasterosteus predatory cues at sexual maturity.
A: In dependence of the Gasterosteus kairomone the body length is significantly increased. B: Time to reach maturity is significantly shortened and C: The number of neonates is significantly increased. Plotted are medians and interquartile ranges. Bonferroni corrected significance levels: *p<0.025; **p<0.005; ***p<0.0005.
Figure 3.
Cholinergically modulated neckteeth expression.
Neckteeth expression in dependence of increasing Chaoborus kairomone concentrations in combination with (A) physostigmine (5 nM) and (B) atropine (5 µM). Physostigmine significantly increases neckteeth expression at low (25%) kairomone concentrations. At high concentrations a maximal expression of neckteeth cannot be exceeded. Atropine significantly reduces neckteeth expression at high (100%) kairomone concentrations in comparison to lower (25%) concentrations. Plotted are medians and interquartile ranges.
Table 1.
Physostigmine (5 nM) effect on morphological defenses in dependence of Chaoborus and Gasterosteus kairomone (Bonferroni-corrected Mann-Whitney U comparison).
Table 2.
Atropine (5 µM) effect on morphological defenses in dependence of Chaoborus and Gasterosteus kairomone (Bonferroni- corrected Mann-Whitney U comparison).
Figure 4.
Gabaergically modulated life history parameters.
A: Body length in dependence of increasing Gasterosteus kairomone concentrations and GABA (15 µM). Body length is significantly reduced by GABA stimulation at high Gasterosteus kairomone concentrations (50% and 100%, Mann-Whitney U comparison p<0.01). B: Generation time is significantly increased by GABA stimulation at low and medium Gasterosteus kairomone concentrations (25% and 50%, Mann- Whitney U comparison p<0.01). C: The fecundity (number of eggs in the brood pouch) is significantly reduced by GABA stimulation at high Gasterosteus kairomone concentrations (75% and 100%, Mann- Whitney U comparison p<0.01).
Table 3.
GABA (15 µM) effect on morphological defenses in dependence of Chaoborus and Gasterosteus kairomone (Bonferroni- corrected Mann-Whitney U comparison).