Temperature- and predator-induced phenotypic plasticity in Bosmina cornuta and B. pellucida (Crustacea: Cladocera)

• Published in: Freshwater biology Vol. 47; no. 10; pp. 1944 - 1955
• Main Authors: Kappes, Heike, Sinsch, Ulrich
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.10.2002; Blackwell Science; Wiley Subscription Services, Inc
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; antennule size; Autoecology; Biological and medical sciences; Bosmina longirostris-complex; cyclomorphosis; Fundamental and applied biological sciences. Psychology; mucrone size; predator avoidance; Protozoa. Invertebrata; Europe; Germany; Predator prey relation; Temperature; Interspecific comparison; Cladocera; Phenotypic plasticity; Environmental factor; Species complex; Crustacea; Freshwater environment; Arthropoda; Morphology; Lakes; Antipredator behavior; Predator; Invertebrata; Morphometry; Branchiopoda; Cyclomorphosis
• ISSN: 0046-5070; 1365-2427
• DOI: 10.1046/j.1365-2427.2002.00943.x

SUMMARY 1. Clones of Bosmina cornuta and B. pellucida (B. longirostris species complex) were derived from samples collected from Scheuermühlenteich and Lake Windsborn(westernGermany). Experimental temperature change (to 10 °C and 20 °C) and exposure to Acanthocyclops vernalis copepods (12 L−1) significantly altered external morphology in laboratory cultures of the two species. Morphological traits were derived from eight log10‐transformed and standardised morphometric distances by factorial analysis: factor 1 represented body size, factor 2, size of appendages and factor 3, the head size. 2. Acclimation of clones to cold water (10 °C, >14 days) led to an increase in body, antennule and mucrone size in B. cornuta and B. pellucida. Moreover, at 10 °C, B. cornuta cultures usually collapsed within a few weeks. Compared to the trials at 10 °C, acclimation to 20 °C (the two species) and to 15 °C (B. pellucida only) left the size of body appendages unchanged. Individuals were unequivocally assigned to each species by discriminant functions. Conspecific individuals that were acclimated to different temperatures between 10 and 20 °C also differed in external morphology, but discriminant analysis yielded misclassification rates of 5.3–23.3%. 3. Morphological response to the presence of copepod predators was weaker than that caused by temperature change. Long‐term exposure of clones to copepod predators induced a significant increase in size of appendages in the two species but left body size unaffected. Again, species identification by discriminant functions could be made without any error, whereas conspecific controls and experimentals were misclassified at rates between 19.4 and 29.5%. 4. It is suggested that temperature is the main proximal cue for Bosmina cyclomorphosis. The distinct response to temperature of B. pellucida and B. cornuta may also account for seasonal differences in abundance observed in field.